1384:
1157:
1065:(figuratively speaking, they together "pull up" or "pull down" it so that it moves). In addition, the dynamic load "helps" them by changing its instant ohmic resistance in the same direction as the input voltages (it increases when the voltage increases and vice versa.) thus keeping up constant total resistance between the two supply rails. There is a full (100%) negative feedback; the two input base voltages and the emitter voltage change simultaneously while the collector currents and the total current do not change. As a result, the output collector voltages do not change as well.
975:
3021:
3057:
1297:
1153:. Thus the differential collector current signal is converted to a single-ended voltage signal without the intrinsic 50% losses, so the gain is doubled. This is achieved by copying the input collector current from the left to the right side, where the magnitudes of the two input signals add. For this purpose, the input of the current mirror is connected to the left output, and the output of the current mirror is connected to the right output of the differential amplifier.
1127:
31:
1900:
938:, and probably others designed by people who worked with Blumlein or his peers. The long-tailed pair has many favorable attributes if used as a switch: largely immune to tube (transistor) variations (of great importance when machines contained 1,000 tubes or more), high gain, gain stability, high input impedance, medium/low output impedance, good clipper (with a not-too-long tail), non-inverting (
942:) and large output voltage swings. One disadvantage is that the output voltage swing (typically ±10–20 V) was imposed upon a high DC voltage (200 V or so), requiring care in signal coupling, usually some form of wide-band DC coupling. Many computers of this time tried to avoid this problem by using only AC-coupled pulse logic, which made them very large and overly complex (
2157:
1638:
1653:
1098:(driven by the higher input voltage) drives all the current. If the resistor at the collector is relatively large, the transistor will saturate. With relatively small collector resistor and moderate overdrive, the emitter can still follow the input signal without saturation. This mode is used in differential switches and
1367:
gates and as switch. When used as a switch, the "left" base/grid is used as signal input and the "right" base/grid is grounded; output is taken from the right collector/plate. When the input is zero or negative, the output is close to zero (but can be not saturated); when the input is positive, the
1271:
The input impedance of the differential pair highly depends on the input mode. At common mode, the two parts behave as common-collector stages with high emitter loads; so, the input impedances are extremely high. At differential mode, they behave as common-emitter stages with grounded emitters; so,
1262:
It is possible to connect a floating source between the two bases, but it is necessary to ensure paths for the biasing base currents. In the case of galvanic source, only one resistor has to be connected between one of the bases and the ground. The biasing current will enter directly this base and
1012:
The differential pair can be used as an amplifier with a single-ended input if one of the inputs is grounded or fixed to a reference voltage (usually, the other collector is used as a single-ended output) This arrangement can be thought of as cascaded common-collector and common-base stages or as a
2624:
More generally, this arrangement can be considered as two interacting voltage followers with negative feedback: the output part of the differential pair acts as a voltage follower with constant input voltage (a voltage stabilizer) producing constant output voltage; the input part acts as a voltage
1243:
The constant current needed could be produced by connecting an element (resistor) with very high resistance between the shared emitter node and the supply rail (negative for NPN and positive for PNP transistors), but that requires a high supply voltage. So in more sophisticated designs, an element
1185:
The quiescent current has to be constant to ensure constant collector voltages at common mode. This requirement is not so important in the case of a differential output, since although their two collector voltages will vary simultaneously their difference (the output voltage) will not vary. But in
982:
With two inputs and two outputs, this forms a differential amplifier stage (Figure 2). The two bases (or grids or gates) are inputs which are differentially amplified (subtracted and multiplied) by the transistor pair; they can be fed with a differential (balanced) input signal, or one input
918:
The long-tailed pair was developed from earlier knowledge of push–pull circuit techniques and measurement bridges. An early circuit which closely resembles a long-tailed pair was published by
British neurophysiologist Bryan Matthews in 1934, and it seems likely that this was intended to be a true
1081:
with a magnitude determined by the common-mode input voltages. The high-resistance emitter element does not play any role—it is shunted by the other low-resistance emitter follower. There is no negative feedback, since the emitter voltage does not change at all when the input base voltages
1055:
The biasing base currents needed to evoke the quiescent collector currents usually come from the ground, pass through the input sources and enter the bases. So, the sources have to be galvanic (DC) to ensure paths for the biasing current and low resistive enough to not create significant voltage
1048:(and so they are highly β-dependent), the differential pair is directly biased from the side of the emitters by sinking/injecting the total quiescent current. The series negative feedback (the emitter degeneration) makes the transistors act as voltage stabilizers; it forces them to adjust their V
1391:
In case the operational amplifier's (non-ideal) input bias current or differential input impedance are a significant effect, one can select a feedback network that improves the effect of common-mode input signal and bias. In Figure 6, current generators model the input bias current at each
1164:
The current mirror copies the left collector current and passes it through the right transistor that produces the right collector current. At this right output of the differential amplifier, the two signal currents (pos. and neg. current changes) are subtracted. In this case (differential input
1076:
In differential mode (the two input voltages change in opposite directions), the two voltage (emitter) followers oppose each other—while one of them tries to increase the voltage of the common emitter point, the other tries to decrease it (figuratively speaking, one of them "pulls up" the
2610:
that represents the high emitter resistance at common mode with a common long tail with a proportional length (at differential mode this tail shortens up to zero). If additional emitter resistors with small resistances are included between the emitters and the common node (to introduce a small
1097:
If the input differential voltage changes significantly (more than about a hundred millivolts), the transistor driven by the lower input voltage turns off and its collector voltage reaches the positive supply rail. At high overdrive the base-emitter junction gets reversed. The other transistor
1064:
In common mode (the two input voltages change in the same directions), the two voltage (emitter) followers cooperate with each other working together on the common high-resistive emitter load (the "long tail"). They all together increase or decrease the voltage of the common emitter point
853:
672:
1340:). For comparison, the old-fashioned inverting single-ended op-amps from the early 1940s could realize only parallel negative feedback by connecting additional resistor networks (an op-amp inverting amplifier is the most popular example). A common application is for the control of
1439:
1929:
1116:
In common mode, the emitter voltage follows the input voltage variations; there is a full negative feedback and the gain is minimum. In differential mode, the emitter voltage is fixed (equal to the instant common input voltage); there is no negative feedback and the gain is
1895:{\displaystyle {V^{-}}'=V_{\text{in}}^{-}R_{\parallel }^{-}/R_{\text{i}}^{-}+V_{\text{out}}R_{\parallel }^{-}/R_{\text{f}}^{-}-I_{\text{b}}^{-}R_{\parallel }^{-};\quad {\text{where}}\quad {R^{-}}'=R_{\parallel }^{-}=R_{\text{i}}^{-}\parallel R_{\text{f}}^{-}.}
1112:, the base-emitter junction of the transistor driven by the lower input voltage breaks down. If the input sources are low resistive, an unlimited current will flow directly through the "diode bridge" between the two input sources and will damage them.
2485:
2625:
follower with varying input voltage trying to change the steady output voltage of the stabilizer. The stabilizer reacts to this intervention by changing its output quantity (current, respectively voltage) that serves as a circuit output.
714:(CMRR), usually defined as the ratio between differential-mode gain and common-mode gain, indicates the ability of the amplifier to accurately cancel voltages that are common to both inputs. The common-mode rejection ratio is defined as
2277:
1308:, or op-amp, is a differential amplifier with very high differential-mode gain, very high input impedance, and low output impedance. An op-amp differential amplifier can be built with predictable and stable gain by applying
371:
885:
is zero, and the CMRR is infinite. Note that a differential amplifier is a more general form of amplifier than one with a single input; by grounding one input of a differential amplifier, a single-ended amplifier results.
720:
1375:. The advantages are high impedance of the differential amplifier input and output and small phase shift between input and output. This application uses only one input and one output of the differential amplifier.
1287:
The common-mode input voltage can vary between the two supply rails but cannot closely reach them since some voltage drops (minimum 1 volt) have to remain across the output transistors of the two current mirrors.
239:
1248:
source/sink (the bottom of Fig. 3) is substituted for the “long tail”. It is usually implemented by a current mirror because of its high compliance voltage (small voltage drop across the output transistor).
540:
1633:{\displaystyle {V^{+}}'=V_{\text{in}}^{+}R_{\parallel }^{+}/R_{\text{i}}^{+}-I_{\text{b}}^{+}R_{\parallel }^{+};\quad {\text{where}}\quad {R^{+}}'=R_{\parallel }^{+}=R_{\text{i}}^{+}\parallel R_{\text{f}}^{+},}
1082:
change. The common quiescent current vigorously steers between the two transistors and the output collector voltages vigorously change. The two transistors mutually ground their emitters; so, although they are
2152:{\displaystyle V_{\text{out}}=A_{\text{ol}}\cdot 2R_{\text{d}}{\frac {{V^{+}}'-{V^{-}}'}{2R_{\parallel }+2R_{\text{d}}}}=({V^{+}}'-{V^{-}}')A_{\text{ol}}R_{\parallel }/(R_{\parallel }\parallel R_{\text{d}}),}
1090:
stages with maximum gain. Bias stability and independence from variations in device parameters can be improved by negative feedback introduced via cathode/emitter resistors with relatively small resistances.
995:
If the differential output is not desired, then only one output can be used (taken from just one of the collectors (or anodes or drains), disregarding the other output; this configuration is referred to as
1263:
indirectly (through the input source) the other one. If the source is capacitive, two resistors have to be connected between the two bases and the ground to ensure different paths for the base currents.
1052:
voltages (base currents) to pass the quiescent current through their collector-emitter junctions. So, due to the negative feedback, the quiescent current depends only slightly on the transistor's β.
1000:. The gain is half that of the stage with differential output. To avoid sacrificing gain, a differential to single-ended converter can be utilized. This is often implemented as a current mirror (
2634:
Interestingly, it is as though the negative feedback has reversed the transistor behavior - the collector current has become an input quantity while the base current serves as an output one.
1186:
the case of a single-ended output, it is extremely important to keep a constant current since the output collector voltage will vary. Thus the higher the resistance of the current source
2288:
532:
500:
438:
406:
130:
98:
534:
are equal, the output will not be zero, as it would be in the ideal case. A more realistic expression for the output of a differential amplifier thus includes a second term:
157:
1238:
1211:
883:
702:
465:
1036:
To explain the circuit operation, four particular modes are isolated below although, in practice, some of them act simultaneously and their effects are superimposed.
2192:
262:
1077:
common point while the other "pulls down" it so that it stays immovable) and vice versa. So, the common point does not change its voltage; it behaves like a
911:. The circuit works the same way for all three-terminal devices with current gain. The bias points of “long-tail” resistor circuit are largely determined by
1336:(op-amp follower, non-inverting amplifier, etc.), where one input is used for the input signal, the other for the feedback signal (usually implemented by
1177:), and the differential to single-ended conversion is completed without gain losses. Fig. 4 shows the transmission characteristic of this circuit.
946:: 18,000 tubes for a 20-digit calculator) or unreliable. DC-coupled circuitry became the norm after the first generation of vacuum-tube computers.
294:
707:
As differential amplifiers are often used to null out noise or bias voltages that appear at both inputs, a low common-mode gain is usually desired.
848:{\displaystyle {\text{CMRR}}=10\log _{10}\left({\frac {A_{\text{d}}}{A_{\text{c}}}}\right)^{2}=20\log _{10}{\frac {A_{\text{d}}}{|A_{\text{c}}|}}.}
2998:
2705:
667:{\displaystyle V_{\text{out}}=A_{\text{d}}(V_{\text{in}}^{+}-V_{\text{in}}^{-})+A_{\text{c}}{\frac {V_{\text{in}}^{+}+V_{\text{in}}^{-}}{2}},}
923:
in 1936. By the end of the 1930s the topology was well established and had been described by various authors, including Frank Offner (1937),
169:
2652:
1056:
drops across them. Otherwise, additional DC elements should be connected between the bases and the ground (or the positive power supply).
1360:. A long-tailed pair can be used as an analog multiplier with the differential voltage as one input and the biasing current as another.
919:
long-tailed pair but was published with a drawing error. The earliest definite long-tailed pair circuit appears in a patent submitted by
34:
Operational amplifier symbol. The inverting and non-inverting inputs are distinguished by "−" and "+" placed in the amplifier triangle. V
2682:
be matched in the inverting and non-inverting legs. For the input bias currents to cancel, the stricter relation given here must obtain.
1312:
feedback (Figure 5). Some kinds of differential amplifier usually include several simpler differential amplifiers. For example, a
1275:
The output impedance of the differential pair is high (especially for the improved differential pair with a current mirror as shown in
2731:
283:
containing internal feedback resistors. It is also a common sub-component of larger integrated circuits handling analog signals.
927:(1937) and Jan Friedrich Toennies (1938), and it was particularly used for detection and measurement of physiological impulses.
42:
are the power-supply voltages; they are often omitted from the diagram for simplicity but must be present in the actual circuit.
1045:
2918:
2817:
1024:
and transistor saturation are avoided. That is why it is used to form emitter-coupled amplifiers (avoiding Miller effect),
2991:
2741:
2651:
differential amplifier, in the way that a high-gain inverting amplifier (op-amp) serves as a component in a low-gain
2591:
987:
circuit. An amplifier with differential output can drive a floating load or another stage with differential input.
2535:. It is as if the input offset current is equivalent to an input offset voltage acting across an input resistance
2507:
It also implies that the common-mode input bias current has cancelled out, leaving only the input offset current
1383:
3136:
2984:
17:
160:
2971:
954:
A differential (long-tailed, emitter-coupled) pair amplifier consists of two amplifying stages with common (
2480:{\displaystyle V_{\text{in}}^{+}-V_{\text{in}}^{-}-R_{\text{i}}I_{\text{b}}^{\Delta }=V_{\text{out}}\left,}
1387:
Figure 6: Differential amplifier with non-ideal op-amp: input bias current and differential input impedance
1313:
3105:
3027:
1372:
1028:
circuits (obtaining two inverse voltages), ECL gates and switches (avoiding transistor saturation), etc.
711:
2972:
Analog
Devices – AN-0990 : Terminating a Differential Amplifier in Single-Ended Input Applications
470:
In practice, however, the gain is not quite equal for the two inputs. This means, for instance, that if
2959:
505:
473:
411:
379:
103:
71:
2700:
1317:
1165:
signal), they are equal and opposite. Thus, the difference is twice the individual signal currents (Δ
1156:
955:
899:
Modern differential amplifiers are usually implemented with a basic two-transistor circuit called a
135:
1418:
1216:
1189:
861:
680:
443:
3065:
1378:
1368:
output is most-positive, dynamic operation being the same as the amplifier use described above.
3100:
2710:
1364:
1337:
1305:
1134:
load (top section in blue) and constant-current biasing (the bottom current source in yellow)
1099:
930:
The long-tailed pair was very successfully used in early
British computing, most notably the
276:
47:
2668:
For the closed-loop common-mode gain to be zero only requires that the ratio of resistances
2851:
2656:
2566:, the value one would obtain through the rule-of-thumb analysis known as "virtual ground".
57:
2272:{\displaystyle R_{\text{i}}^{+}=R_{\text{i}}^{-},\quad R_{\text{f}}^{+}=R_{\text{f}}^{-},}
974:
8:
2878:
1321:
2855:
1357:
280:
265:
247:
2757:
Eglin, J. M. (1 May 1929). "A Direct-Current
Amplifier for Measuring Small Currents".
2737:
2587:
1333:
1109:
271:
Single amplifiers are usually implemented by either adding the appropriate feedback
3041:
2965:
2893:
2859:
2802:
2797:
2785:
2766:
2542:, which is the source resistance of the feedback network into the input terminals.
1245:
1213:
in the original circuit of Fig. 2, the lower (better) is the common-mode gain
1083:
3020:
2582:
Details of the long-tailed pair circuitry used in early computing can be found in
2611:
negative feedback at differential mode), they can be figuratively represented by
963:
366:{\displaystyle V_{\text{out}}=A_{\text{d}}(V_{\text{in}}^{+}-V_{\text{in}}^{-}),}
27:
Electrical circuit component which amplifies the difference of two analog signals
1296:
3036:
1345:
1341:
1146:
1131:
1087:
1078:
1025:
984:
65:
3130:
3074:
3056:
1379:
Symmetrical feedback network eliminates common-mode gain and common-mode bias
1021:
959:
920:
3079:
2946:. IEEE Engineering in Medicine and Biology, May/June 1996, p. 116–117.
2770:
2695:
924:
912:
3084:
3046:
1356:, which is also usually found as the differential element in most op-amp
1349:
1150:
908:
2976:
1352:, a common arrangement for implementing a differential amplifier is the
3007:
2490:
which implies that the closed-loop gain for the differential signal is
1332:
Differential amplifiers are found in many circuits that utilize series
1108:
If the input voltage continues increasing and exceeds the base-emitter
2897:
2863:
1016:
The emitter-coupled amplifier is compensated for temperature drifts, V
234:{\displaystyle V_{\text{out}}=A(V_{\text{in}}^{+}-V_{\text{in}}^{-}),}
3010:
931:
2842:
Offner, Franklin (1937). "Push-Pull
Resistance Coupled Amplifiers".
1149:(the top blue section in Fig. 3), whose output part acts as an
1126:
272:
1291:
3110:
61:
1348:, as well as for signal amplification applications. In discrete
30:
64:
but suppresses any voltage common to the two inputs. It is an
943:
935:
2647:
differential amplifier (op-amp) is used as a component of a
1244:
with high differential (dynamic) resistance approximating a
2552:
is much larger than unity, the closed-loop voltage gain is
907:. This circuit was originally implemented using a pair of
286:
2655:. This paradox of negative-feedback amplifiers impeded
1324:
are often built from a combination of several op-amps.
1121:
2291:
2195:
1932:
1656:
1442:
1219:
1192:
864:
723:
683:
543:
508:
476:
446:
414:
382:
297:
250:
172:
138:
106:
74:
1905:
The output of the op-amp is just the open-loop gain
1363:
A differential amplifier is used as the input stage
1044:
In contrast with classic amplifying stages that are
2186:These equations undergo a great simplification if
2733:Comprehensive Dictionary of Electrical Engineering
2479:
2271:
2151:
1894:
1632:
1232:
1205:
1180:
877:
847:
696:
666:
526:
494:
459:
432:
400:
365:
256:
233:
151:
124:
92:
2504:, but the common-mode gain is identically zero.
1130:Figure 3: An improved long-tailed pair with
915:and less so by active-component characteristics.
858:In a perfectly symmetric differential amplifier,
704:is called the common-mode gain of the amplifier.
3128:
60:that amplifies the difference between two input
2545:Finally, as long as the open-loop voltage gain
1292:Operational amplifier as differential amplifier
1406:represent the input bias current at terminals
2992:
1252:
1145:The collector resistors can be replaced by a
2643:In this arrangement it seems strange that a
1300:Figure 5: Op-amp differential amplifier
163:to the difference between the two voltages:
1140:
2999:
2985:
2786:"Proceedings of the Physiological Society"
1371:The differential amplifier is used in the
3006:
2801:
2784:Matthews, Bryan H. C. (1 December 1934).
2759:Journal of the Optical Society of America
2528:still present, and with a coefficient of
1266:
978:Figure 2: A classic long-tailed pair
2944:Who Invented the Differential Amplifier?
2783:
2736:(2nd ed.). CRC Press. p. 190.
2729:
2584:Alan Turing’s Automatic Computing Engine
1916:times the differential input impedance 2
1382:
1295:
1257:
1155:
1125:
973:
894:
29:
2876:
2723:
934:model and descendants, Maurice Wilkes’
287:Theory of amplifier in numerical method
14:
3129:
2841:
990:
969:
3115:
2980:
2966:A testbench for differential circuits
2756:
1912:times the differential input current
1353:
1282:
1160:Figure 4: Transmission characteristic
1007:
1068:
1122:Differential amplifier improvements
889:
24:
2348:
1643:while for the network driving the
25:
3148:
2953:
2706:Op-amp differential configuration
2594:) in Part IV, "ELECTRONICS".
949:
527:{\displaystyle V_{\text{in}}^{-}}
495:{\displaystyle V_{\text{in}}^{+}}
433:{\displaystyle V_{\text{in}}^{-}}
401:{\displaystyle V_{\text{in}}^{+}}
159:, in which the output is ideally
125:{\displaystyle V_{\text{in}}^{+}}
93:{\displaystyle V_{\text{in}}^{-}}
3055:
3019:
2886:Review of Scientific Instruments
2844:Review of Scientific Instruments
2586:(Oxford University Press, 2005,
1046:biased from the side of the base
2662:
2637:
2628:
2618:
2597:
2232:
1817:
1811:
1555:
1549:
1327:
1181:Emitter constant current source
2936:
2911:
2870:
2835:
2810:
2803:10.1113/jphysiol.1934.sp003151
2777:
2750:
2576:
2143:
2117:
2089:
2049:
1272:the input impedances are low.
1059:
835:
820:
603:
567:
357:
321:
225:
189:
152:{\displaystyle V_{\text{out}}}
13:
1:
2716:
1276:
1086:stages, they actually act as
1001:
940:EDSAC contained no inverters!
2730:Laplante, Philip A. (2005).
2569:
1421:for the network driving the
1314:fully differential amplifier
1233:{\displaystyle A_{\text{c}}}
1206:{\displaystyle R_{\text{e}}}
1031:
1013:buffered common-base stage.
983:could be grounded to form a
878:{\displaystyle A_{\text{c}}}
697:{\displaystyle A_{\text{c}}}
460:{\displaystyle A_{\text{d}}}
440:are the input voltages, and
7:
3106:Complementary feedback pair
3028:Bipolar junction transistor
2689:
1373:cathode follower oscillator
712:common-mode rejection ratio
10:
3153:
2960:BJT Differential Amplifier
2282:resulting in the relation
1253:Interfacing considerations
1039:
467:is the differential gain.
45:
3093:
3064:
3053:
3026:
3017:
2962:– Circuit and explanation
2879:"Cathode Phase Inversion"
2877:Schmitt, Otto H. (1941).
2790:The Journal of Physiology
2701:Instrumentation amplifier
1318:instrumentation amplifier
2606:is a figurative name of
1141:Collector current mirror
3066:Field-effect transistor
1425:terminal has a voltage
2823:. Freepatensonline.com
2771:10.1364/JOSA.18.000393
2481:
2273:
2153:
1896:
1634:
1388:
1338:operational amplifiers
1301:
1267:Input/output impedance
1234:
1207:
1161:
1135:
1020:is cancelled, and the
979:
879:
849:
698:
668:
528:
496:
461:
434:
402:
367:
279:, or with a dedicated
258:
235:
153:
126:
94:
54:differential amplifier
43:
3137:Electronic amplifiers
3101:Darlington transistor
3094:Multiple transistors:
2711:Emitter-coupled logic
2659:obtaining his patent.
2482:
2274:
2154:
1897:
1635:
1386:
1365:emitter coupled logic
1306:operational amplifier
1299:
1258:Floating input source
1235:
1208:
1159:
1129:
977:
895:Historical background
880:
850:
699:
669:
529:
497:
462:
435:
403:
368:
259:
236:
154:
127:
95:
48:Operational amplifier
33:
2289:
2193:
1930:
1654:
1440:
1217:
1190:
1002:Figure 3, below
862:
721:
681:
541:
506:
474:
444:
412:
380:
295:
248:
170:
136:
104:
72:
58:electronic amplifier
2919:"US Patent 2147940"
2856:1937RScI....8...20O
2818:"US Patent 2185367"
2653:inverting amplifier
2352:
2324:
2306:
2265:
2247:
2228:
2210:
1888:
1870:
1852:
1807:
1792:
1774:
1754:
1726:
1706:
1691:
1626:
1608:
1590:
1545:
1530:
1512:
1492:
1477:
1419:Thévenin equivalent
1358:integrated circuits
1322:isolation amplifier
998:single-ended output
991:Single-ended output
970:Differential output
654:
636:
602:
584:
523:
491:
429:
397:
356:
338:
224:
206:
121:
89:
2970:Application Note:
2477:
2338:
2310:
2292:
2269:
2251:
2233:
2214:
2196:
2169:is the average of
2149:
1892:
1874:
1856:
1838:
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1712:
1692:
1677:
1630:
1612:
1594:
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1516:
1498:
1478:
1463:
1389:
1302:
1283:Input/output range
1230:
1203:
1162:
1136:
1008:Single-ended input
980:
901:“long-tailed” pair
875:
845:
694:
664:
640:
622:
588:
570:
524:
509:
492:
477:
457:
430:
415:
398:
383:
363:
342:
324:
281:integrated circuit
268:of the amplifier.
254:
231:
210:
192:
149:
122:
107:
90:
75:
44:
3124:
3123:
2898:10.1063/1.1769796
2864:10.1063/1.1752180
2467:
2464:
2460:
2447:
2434:
2423:
2411:
2393:
2390:
2380:
2363:
2345:
2335:
2317:
2299:
2258:
2240:
2221:
2203:
2140:
2099:
2044:
2040:
1969:
1953:
1940:
1881:
1863:
1815:
1785:
1767:
1737:
1719:
1684:
1619:
1601:
1553:
1523:
1505:
1470:
1334:negative feedback
1227:
1200:
1110:breakdown voltage
1069:Differential mode
905:differential pair
872:
840:
831:
815:
775:
772:
762:
727:
691:
659:
647:
629:
616:
595:
577:
564:
551:
516:
484:
454:
422:
390:
349:
331:
318:
305:
257:{\displaystyle A}
217:
199:
180:
146:
114:
82:
16:(Redirected from
3144:
3116:Long-tailed pair
3059:
3042:Common collector
3023:
3001:
2994:
2987:
2978:
2977:
2947:
2940:
2934:
2933:
2931:
2929:
2923:
2915:
2909:
2908:
2906:
2904:
2883:
2874:
2868:
2867:
2839:
2833:
2832:
2830:
2828:
2822:
2814:
2808:
2807:
2805:
2796:(suppl): 28–29.
2781:
2775:
2774:
2754:
2748:
2747:
2727:
2683:
2666:
2660:
2641:
2635:
2632:
2626:
2622:
2616:
2601:
2595:
2580:
2486:
2484:
2483:
2478:
2473:
2469:
2468:
2466:
2465:
2463:
2462:
2461:
2458:
2449:
2448:
2445:
2436:
2435:
2432:
2425:
2424:
2421:
2415:
2413:
2412:
2409:
2399:
2394:
2392:
2391:
2388:
2382:
2381:
2378:
2372:
2365:
2364:
2361:
2351:
2346:
2343:
2337:
2336:
2333:
2323:
2318:
2315:
2305:
2300:
2297:
2278:
2276:
2275:
2270:
2264:
2259:
2256:
2246:
2241:
2238:
2227:
2222:
2219:
2209:
2204:
2201:
2158:
2156:
2155:
2150:
2142:
2141:
2138:
2129:
2128:
2116:
2111:
2110:
2101:
2100:
2097:
2088:
2084:
2083:
2082:
2068:
2064:
2063:
2062:
2045:
2043:
2042:
2041:
2038:
2026:
2025:
2012:
2011:
2007:
2006:
2005:
1991:
1987:
1986:
1985:
1973:
1971:
1970:
1967:
1955:
1954:
1951:
1942:
1941:
1938:
1901:
1899:
1898:
1893:
1887:
1882:
1879:
1869:
1864:
1861:
1851:
1846:
1834:
1830:
1829:
1828:
1816:
1813:
1806:
1801:
1791:
1786:
1783:
1773:
1768:
1765:
1759:
1753:
1748:
1739:
1738:
1735:
1725:
1720:
1717:
1711:
1705:
1700:
1690:
1685:
1682:
1673:
1669:
1668:
1667:
1639:
1637:
1636:
1631:
1625:
1620:
1617:
1607:
1602:
1599:
1589:
1584:
1572:
1568:
1567:
1566:
1554:
1551:
1544:
1539:
1529:
1524:
1521:
1511:
1506:
1503:
1497:
1491:
1486:
1476:
1471:
1468:
1459:
1455:
1454:
1453:
1429:' and impedance
1354:long-tailed pair
1246:constant current
1239:
1237:
1236:
1231:
1229:
1228:
1225:
1212:
1210:
1209:
1204:
1202:
1201:
1198:
1169: − (−Δ
1084:common-collector
966:) degeneration.
890:Long-tailed pair
884:
882:
881:
876:
874:
873:
870:
854:
852:
851:
846:
841:
839:
838:
833:
832:
829:
823:
817:
816:
813:
807:
802:
801:
786:
785:
780:
776:
774:
773:
770:
764:
763:
760:
754:
744:
743:
728:
725:
703:
701:
700:
695:
693:
692:
689:
673:
671:
670:
665:
660:
655:
653:
648:
645:
635:
630:
627:
620:
618:
617:
614:
601:
596:
593:
583:
578:
575:
566:
565:
562:
553:
552:
549:
533:
531:
530:
525:
522:
517:
514:
501:
499:
498:
493:
490:
485:
482:
466:
464:
463:
458:
456:
455:
452:
439:
437:
436:
431:
428:
423:
420:
407:
405:
404:
399:
396:
391:
388:
372:
370:
369:
364:
355:
350:
347:
337:
332:
329:
320:
319:
316:
307:
306:
303:
263:
261:
260:
255:
240:
238:
237:
232:
223:
218:
215:
205:
200:
197:
182:
181:
178:
158:
156:
155:
150:
148:
147:
144:
131:
129:
128:
123:
120:
115:
112:
99:
97:
96:
91:
88:
83:
80:
68:with two inputs
21:
3152:
3151:
3147:
3146:
3145:
3143:
3142:
3141:
3127:
3126:
3125:
3120:
3089:
3060:
3051:
3024:
3013:
3005:
2956:
2951:
2950:
2941:
2937:
2927:
2925:
2921:
2917:
2916:
2912:
2902:
2900:
2892:(11): 548–551.
2881:
2875:
2871:
2840:
2836:
2826:
2824:
2820:
2816:
2815:
2811:
2782:
2778:
2755:
2751:
2744:
2728:
2724:
2719:
2692:
2687:
2686:
2681:
2674:
2667:
2663:
2642:
2638:
2633:
2629:
2623:
2619:
2608:high resistance
2602:
2598:
2581:
2577:
2572:
2565:
2558:
2551:
2541:
2534:
2527:
2520:
2513:
2503:
2496:
2457:
2453:
2444:
2440:
2431:
2427:
2426:
2420:
2416:
2414:
2408:
2404:
2403:
2398:
2387:
2383:
2377:
2373:
2371:
2370:
2366:
2360:
2356:
2347:
2342:
2332:
2328:
2319:
2314:
2301:
2296:
2290:
2287:
2286:
2260:
2255:
2242:
2237:
2223:
2218:
2205:
2200:
2194:
2191:
2190:
2182:
2175:
2168:
2137:
2133:
2124:
2120:
2112:
2106:
2102:
2096:
2092:
2078:
2074:
2073:
2072:
2058:
2054:
2053:
2052:
2037:
2033:
2021:
2017:
2013:
2001:
1997:
1996:
1995:
1981:
1977:
1976:
1975:
1974:
1972:
1966:
1962:
1950:
1946:
1937:
1933:
1931:
1928:
1927:
1922:
1911:
1883:
1878:
1865:
1860:
1847:
1842:
1824:
1820:
1819:
1818:
1812:
1802:
1797:
1787:
1782:
1769:
1764:
1755:
1749:
1744:
1734:
1730:
1721:
1716:
1707:
1701:
1696:
1686:
1681:
1663:
1659:
1658:
1657:
1655:
1652:
1651:
1621:
1616:
1603:
1598:
1585:
1580:
1562:
1558:
1557:
1556:
1550:
1540:
1535:
1525:
1520:
1507:
1502:
1493:
1487:
1482:
1472:
1467:
1449:
1445:
1444:
1443:
1441:
1438:
1437:
1405:
1398:
1381:
1330:
1294:
1285:
1269:
1260:
1255:
1224:
1220:
1218:
1215:
1214:
1197:
1193:
1191:
1188:
1187:
1183:
1143:
1124:
1071:
1062:
1051:
1042:
1034:
1019:
1010:
993:
972:
952:
897:
892:
869:
865:
863:
860:
859:
834:
828:
824:
819:
818:
812:
808:
806:
797:
793:
781:
769:
765:
759:
755:
753:
749:
748:
739:
735:
724:
722:
719:
718:
688:
684:
682:
679:
678:
649:
644:
631:
626:
621:
619:
613:
609:
597:
592:
579:
574:
561:
557:
548:
544:
542:
539:
538:
518:
513:
507:
504:
503:
486:
481:
475:
472:
471:
451:
447:
445:
442:
441:
424:
419:
413:
410:
409:
392:
387:
381:
378:
377:
351:
346:
333:
328:
315:
311:
302:
298:
296:
293:
292:
289:
249:
246:
245:
219:
214:
201:
196:
177:
173:
171:
168:
167:
143:
139:
137:
134:
133:
132:and one output
116:
111:
105:
102:
101:
84:
79:
73:
70:
69:
50:
41:
37:
28:
23:
22:
15:
12:
11:
5:
3150:
3140:
3139:
3122:
3121:
3119:
3118:
3113:
3108:
3103:
3097:
3095:
3091:
3090:
3088:
3087:
3082:
3077:
3071:
3069:
3062:
3061:
3054:
3052:
3050:
3049:
3044:
3039:
3037:Common emitter
3033:
3031:
3025:
3018:
3015:
3014:
3004:
3003:
2996:
2989:
2981:
2975:
2974:
2968:
2963:
2955:
2954:External links
2952:
2949:
2948:
2942:Geddes, L. A.
2935:
2910:
2869:
2834:
2809:
2776:
2765:(5): 393–402.
2749:
2743:978-1420037807
2742:
2721:
2720:
2718:
2715:
2714:
2713:
2708:
2703:
2698:
2691:
2688:
2685:
2684:
2679:
2672:
2661:
2636:
2627:
2617:
2596:
2574:
2573:
2571:
2568:
2563:
2556:
2549:
2539:
2532:
2525:
2518:
2511:
2501:
2494:
2488:
2487:
2476:
2472:
2456:
2452:
2443:
2439:
2430:
2419:
2407:
2402:
2397:
2386:
2376:
2369:
2359:
2355:
2350:
2341:
2331:
2327:
2322:
2313:
2309:
2304:
2295:
2280:
2279:
2268:
2263:
2254:
2250:
2245:
2236:
2231:
2226:
2217:
2213:
2208:
2199:
2180:
2173:
2166:
2160:
2159:
2148:
2145:
2136:
2132:
2127:
2123:
2119:
2115:
2109:
2105:
2095:
2091:
2087:
2081:
2077:
2071:
2067:
2061:
2057:
2051:
2048:
2036:
2032:
2029:
2024:
2020:
2016:
2010:
2004:
2000:
1994:
1990:
1984:
1980:
1965:
1961:
1958:
1949:
1945:
1936:
1920:
1909:
1903:
1902:
1891:
1886:
1877:
1873:
1868:
1859:
1855:
1850:
1845:
1841:
1837:
1833:
1827:
1823:
1810:
1805:
1800:
1796:
1790:
1781:
1777:
1772:
1763:
1758:
1752:
1747:
1743:
1733:
1729:
1724:
1715:
1710:
1704:
1699:
1695:
1689:
1680:
1676:
1672:
1666:
1662:
1641:
1640:
1629:
1624:
1615:
1611:
1606:
1597:
1593:
1588:
1583:
1579:
1575:
1571:
1565:
1561:
1548:
1543:
1538:
1534:
1528:
1519:
1515:
1510:
1501:
1496:
1490:
1485:
1481:
1475:
1466:
1462:
1458:
1452:
1448:
1414:respectively.
1403:
1396:
1380:
1377:
1329:
1326:
1293:
1290:
1284:
1281:
1268:
1265:
1259:
1256:
1254:
1251:
1223:
1196:
1182:
1179:
1147:current mirror
1142:
1139:
1132:current-mirror
1123:
1120:
1088:common-emitter
1079:virtual ground
1070:
1067:
1061:
1058:
1049:
1041:
1038:
1033:
1030:
1026:phase splitter
1017:
1009:
1006:
992:
989:
985:phase splitter
971:
968:
951:
950:Configurations
948:
896:
893:
891:
888:
868:
856:
855:
844:
837:
827:
822:
811:
805:
800:
796:
792:
789:
784:
779:
768:
758:
752:
747:
742:
738:
734:
731:
687:
675:
674:
663:
658:
652:
643:
639:
634:
625:
612:
608:
605:
600:
591:
587:
582:
573:
569:
560:
556:
547:
521:
512:
489:
480:
450:
427:
418:
395:
386:
374:
373:
362:
359:
354:
345:
341:
336:
327:
323:
314:
310:
301:
288:
285:
275:to a standard
253:
242:
241:
230:
227:
222:
213:
209:
204:
195:
191:
188:
185:
176:
142:
119:
110:
87:
78:
66:analog circuit
39:
35:
26:
18:Long-tail pair
9:
6:
4:
3:
2:
3149:
3138:
3135:
3134:
3132:
3117:
3114:
3112:
3109:
3107:
3104:
3102:
3099:
3098:
3096:
3092:
3086:
3083:
3081:
3078:
3076:
3075:Common source
3073:
3072:
3070:
3067:
3063:
3058:
3048:
3045:
3043:
3040:
3038:
3035:
3034:
3032:
3029:
3022:
3016:
3012:
3009:
3002:
2997:
2995:
2990:
2988:
2983:
2982:
2979:
2973:
2969:
2967:
2964:
2961:
2958:
2957:
2945:
2939:
2920:
2914:
2899:
2895:
2891:
2887:
2880:
2873:
2865:
2861:
2857:
2853:
2849:
2845:
2838:
2819:
2813:
2804:
2799:
2795:
2791:
2787:
2780:
2772:
2768:
2764:
2760:
2753:
2745:
2739:
2735:
2734:
2726:
2722:
2712:
2709:
2707:
2704:
2702:
2699:
2697:
2694:
2693:
2678:
2671:
2665:
2658:
2654:
2650:
2646:
2640:
2631:
2621:
2614:
2609:
2605:
2600:
2593:
2592:0-19-856593-3
2589:
2585:
2579:
2575:
2567:
2562:
2555:
2548:
2543:
2538:
2531:
2524:
2521: −
2517:
2510:
2505:
2500:
2497: −
2493:
2474:
2470:
2454:
2450:
2441:
2437:
2428:
2417:
2405:
2400:
2395:
2384:
2374:
2367:
2357:
2353:
2339:
2329:
2325:
2320:
2311:
2307:
2302:
2293:
2285:
2284:
2283:
2266:
2261:
2252:
2248:
2243:
2234:
2229:
2224:
2215:
2211:
2206:
2197:
2189:
2188:
2187:
2184:
2179:
2172:
2165:
2146:
2134:
2130:
2125:
2121:
2113:
2107:
2103:
2093:
2085:
2079:
2075:
2069:
2065:
2059:
2055:
2046:
2034:
2030:
2027:
2022:
2018:
2014:
2008:
2002:
1998:
1992:
1988:
1982:
1978:
1963:
1959:
1956:
1947:
1943:
1934:
1926:
1925:
1924:
1919:
1915:
1908:
1889:
1884:
1875:
1871:
1866:
1857:
1853:
1848:
1843:
1839:
1835:
1831:
1825:
1821:
1808:
1803:
1798:
1794:
1788:
1779:
1775:
1770:
1761:
1756:
1750:
1745:
1741:
1731:
1727:
1722:
1713:
1708:
1702:
1697:
1693:
1687:
1678:
1674:
1670:
1664:
1660:
1650:
1649:
1648:
1646:
1627:
1622:
1613:
1609:
1604:
1595:
1591:
1586:
1581:
1577:
1573:
1569:
1563:
1559:
1546:
1541:
1536:
1532:
1526:
1517:
1513:
1508:
1499:
1494:
1488:
1483:
1479:
1473:
1464:
1460:
1456:
1450:
1446:
1436:
1435:
1434:
1432:
1428:
1424:
1420:
1415:
1413:
1409:
1402:
1395:
1385:
1376:
1374:
1369:
1366:
1361:
1359:
1355:
1351:
1347:
1343:
1339:
1335:
1325:
1323:
1319:
1315:
1311:
1307:
1298:
1289:
1280:
1278:
1277:Figure 3
1273:
1264:
1250:
1247:
1241:
1221:
1194:
1178:
1176:
1172:
1168:
1158:
1154:
1152:
1148:
1138:
1133:
1128:
1119:
1118:
1113:
1111:
1107:
1103:
1101:
1096:
1092:
1089:
1085:
1080:
1075:
1066:
1057:
1053:
1047:
1037:
1029:
1027:
1023:
1022:Miller effect
1014:
1005:
1003:
999:
988:
986:
976:
967:
965:
961:
957:
947:
945:
941:
937:
933:
928:
926:
922:
921:Alan Blumlein
916:
914:
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906:
902:
887:
866:
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803:
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787:
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766:
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632:
623:
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416:
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325:
312:
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291:
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284:
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274:
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220:
211:
207:
202:
193:
186:
183:
174:
166:
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140:
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108:
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76:
67:
63:
59:
56:is a type of
55:
49:
32:
19:
3080:Common drain
2943:
2938:
2926:. Retrieved
2924:. Google Inc
2913:
2901:. Retrieved
2889:
2885:
2872:
2850:(1): 20–21.
2847:
2843:
2837:
2825:. Retrieved
2812:
2793:
2789:
2779:
2762:
2758:
2752:
2732:
2725:
2696:Gilbert cell
2676:
2669:
2664:
2657:Harold Black
2648:
2644:
2639:
2630:
2620:
2612:
2607:
2603:
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2578:
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2163:
2161:
1923:, therefore
1917:
1913:
1906:
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1644:
1642:
1430:
1426:
1422:
1416:
1411:
1407:
1400:
1393:
1390:
1370:
1362:
1331:
1328:Applications
1309:
1303:
1286:
1274:
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1063:
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1035:
1015:
1011:
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994:
981:
953:
939:
929:
925:Otto Schmitt
917:
909:vacuum tubes
904:
900:
898:
857:
709:
706:
676:
469:
375:
270:
243:
161:proportional
53:
51:
3085:Common gate
3047:Common base
2928:16 February
2903:15 February
2827:15 February
2613:short tails
1350:electronics
1151:active load
1095:Overdriven.
1060:Common mode
3011:amplifiers
3008:Transistor
2717:References
1647:terminal:
1392:terminal;
1106:Breakdown.
46:See also:
2645:high-gain
2604:Long-tail
2570:Footnotes
2451:∥
2438:∥
2349:Δ
2326:−
2321:−
2308:−
2262:−
2225:−
2131:∥
2126:∥
2108:∥
2080:−
2070:−
2023:∥
2003:−
1993:−
1957:⋅
1885:−
1872:∥
1867:−
1849:−
1844:∥
1826:−
1804:−
1799:∥
1789:−
1776:−
1771:−
1751:−
1746:∥
1723:−
1703:−
1698:∥
1688:−
1665:−
1610:∥
1582:∥
1537:∥
1514:−
1484:∥
1032:Operation
932:Pilot ACE
913:Ohm's law
804:
746:
651:−
599:−
586:−
520:−
426:−
353:−
340:−
273:resistors
221:−
208:−
86:−
3131:Category
2690:See also
2649:low-gain
2086:′
2066:′
2009:′
1989:′
1832:′
1671:′
1570:′
1457:′
1320:, or an
1310:negative
1117:maximum.
62:voltages
3111:Cascode
2852:Bibcode
1102:gates.
1074:Normal.
1040:Biasing
964:cathode
956:emitter
264:is the
2740:
2590:
2162:where
1346:servos
1342:motors
1173:) = 2Δ
960:source
677:where
376:where
277:op-amp
244:where
2922:(PDF)
2882:(PDF)
2821:(PDF)
1814:where
1552:where
1316:, an
944:ENIAC
936:EDSAC
38:and V
2930:2016
2905:2016
2829:2016
2738:ISBN
2588:ISBN
2176:and
1417:The
1410:and
1399:and
726:CMRR
710:The
502:and
408:and
266:gain
100:and
2894:doi
2860:doi
2798:doi
2767:doi
2362:out
1939:out
1736:out
1433:':
1344:or
1304:An
1279:).
1100:ECL
1004:).
962:or
903:or
795:log
737:log
550:out
304:out
179:out
145:out
3133::
2890:12
2888:.
2884:.
2858:.
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2794:81
2792:.
2788:.
2763:18
2761:.
2675:/
2550:ol
2514:=
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2183:.
2181:||
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1952:ol
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1050:BE
1018:BE
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2831:.
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