Circuits which can be designed with TransistorAmp software

TransistorAmp software is able to design a transistor amplifier circuit in common-base configuration, common-collector configuration, and common-emitter configuration. The tool chooses automatically the apropriate schematic for your input. Here are all schematics shown which can be dimensioned with TransistorAmp:

Common-base circuit

The common-base circuit is needed most for the design of radio frequency applications. For designing an amplifier in common-base configuration, open TransistorAmp software and click on New Amplifier - Common-Base circuit. Here you can see the schematic of the common-base circuit with NPN transistor (left) and with PNP transistor (right).

common-base circuit with NPN transistor common-base circuit with PNP transistor

Common-emitter circuit, complete

The common-emitter circuit offers current gain and voltage gain, and requires a complicated calculation of the component values. For designing an amplifier in common-emitter configuration, open TransistorAmp software and click on New Amplifier - Common-Emitter circuit.

Here you can see the schematic of the common-emitter circuit with NPN transistor (left) and with PNP transistor (right), where the emitter resistor is partly capacitive bypassed by C3 and R5. Thereby, the circuit is able to deliver a high gain, and it has a stable bias point. This means, changes of temperature have only small impact on the bias point.

common-emitter circuit with NPN transistor common-emitter circuit with PNP transistor

Common-emitter circuit, simplified

If the desired gain of the common-emitter circuit is not very high, the capacitive bypass of the emitter resistor can be omitted, so the circuit can be simplified. TransistorAmp detects automatically, in which cases that simplification can be made, and chooses the apropriate schematic. Here you can see the schematic of the simplified common-emitter circuit with NPN transistor (left) and with PNP transistor (right).

simplified common-emitter circuit with NPN transistor simplified common-emitter circuit with PNP transistor

Common-collector circuit

The common-collector circuit offers a high current gain, and outputs the input voltage nearly unchanged. Thereby, a load of lower impedance can be connected to the output of the circuit. That is the reason why the common-collector circuit is also called an impedance converter. Here you can see the schematic of the common-collector circuit with NPN transistor (left) and with PNP transistor (right).

common-collector circuit with NPN transistor common-collector circuit with PNP transistor