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What would be an effective BJT transistor configuration for implementing an amplifier with a current gain of greater than 1000? This can be a multistage configuration, but it may only use BJT transistors. I was thinking of using a common-collector configuration for such a purpose. What would be appropriate biases for the resistors in the amplifiers (along with capacitor values if there any worth noting)?

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    \$\begingroup\$ You don't say a thing about the input or output, or power supply rails, or anything much else. Given that the input and output is abstract and unknown, and there's no power source, what's wrong with a Darlington? \$\endgroup\$ – jonk Nov 27 '16 at 18:38
  • \$\begingroup\$ Which gain? Voltage/current/power gain? A CC stage is an emitter follower: you can't have voltage gain with that. Moreover, can you specify the application you are trying to address? Is it sort of university assignment (otherwise, why restrict it to just BJTs?). What kind of bandwidth and frequency range? As @jonk hinted, there are too many missing specs to nail down a suitable design. \$\endgroup\$ – Lorenzo Donati supports Monica Nov 27 '16 at 18:43
  • \$\begingroup\$ @LorenzoDonati He said "current gain." Unless I missed something. \$\endgroup\$ – jonk Nov 27 '16 at 18:44
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    \$\begingroup\$ Darlington stage. en.wikipedia.org/wiki/Darlington_transistor \$\endgroup\$ – Mario Nov 27 '16 at 18:56
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    \$\begingroup\$ Darlington or Sziklai pair is the easiest. \$\endgroup\$ – Spehro Pefhany Nov 27 '16 at 19:30
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As mentioned in the comments to your question, there are two simple beta-boosting configurations: Darlington and Sziklai.

For both configurations the effective beta (current gain) is a multiplication of the betas of the two transistors. Below are the schematics for these two configurations.

pay attention that the resistor in both cases is not necessary but it helps to improve the slow response time of these configurations and prevents leakage current through Q1 from biasing Q2 into conduction. Also make sure to choose its value so as not to steal substantial base current from Q2.

schematic

simulate this circuit – Schematic created using CircuitLab

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