Common-base, common-injection, common-set basic amplification circuit

1. How to determine whether a basic amplification circuit is a common-base, co-injection or a common set?

Remove the input, the output side, the rest is the common end. The following figure:

The UI is connected to the base pole, and the UO is the common collector.

2. Basic Amplification Circuit:

2-1. Co-emitting minimal signal amplifier

Function: Amplify the small amplitude voltage signal

Working principle: Q1 is connected to the common-injection configuration single-tube amplifier, R1,R2 provides the base bias voltage, R4 stable operating point, R3 is the collector load resistance. R5 is the load, R6 is the internal resistance of the signal source.

Signal source voltage changes caused Q1 IB changes, resulting in IC changes, after R3 conversion to VCE changes, through C2 AC-coupled voltage output to R5.

Normal operating conditions: Q1 in the amplification area, measuring the Q1 of the collector voltage of about 6V.

Debugging method: Adjust the Resistance R1, measure the Q1 's collector voltage to 6V.

Measurement parameters:

1) measuring the end voltage of the signal source VS,Q1 the AC voltage VI of the base pole, the AC voltage of the resistor R5 Vo, calculates the voltage gain of AV and the source voltage gain AVS.

2) measure the phase difference between the input signal and the output signal.

3) Increase the frequency of the input signal, the input voltage is constant, when the output signal amplitude is reduced to 0.7 times times the low frequency when the input signal frequency is recorded, so that the pass-band BW.

4) Increase the input signal amplitude and measure the output signal, and record the input signal and output signal amplitude when the output signal starts clipping.

5) measure the power input current and calculate the efficiency of the amplifier.

2-2. Common collector small signal amplifier

Function: Voltage signal Impedance Transform

Operating principle: Q1 is connected to a single-tube amplifier, R1,R2 provides a base bias voltage, R4 stable operating point, R5 for the load, R6 for the signal source resistance.

Signal source voltage changes caused by Q1 IB changes, resulting in IE changes, because IE is much larger than IB, so can achieve current amplification (impedance transformation function).

Normal operating conditions: Q1 in the amplification area, the measurement of the Q1 emitter voltage of about 6V.

Debugging method: Adjust the Resistance R1, measure the emitter voltage of Q1 to 6V.

Measurement parameters:

1) measuring the end voltage of the signal source VS,Q1 the AC voltage VI of the base pole, the AC voltage of the resistor R5 Vo, calculates the voltage gain of AV and the source voltage gain AVS.

2) measure the phase difference between the input signal and the output signal.

3) Increase the frequency of the input signal, the input voltage is constant, when the output signal amplitude is reduced to 0.7 times times the low frequency when the input signal frequency is recorded, so that the pass-band BW.

4) Increase the input signal amplitude and measure the output signal, and record the input signal and output signal amplitude when the output signal starts clipping.

5) measure the power input current and calculate the efficiency of the amplifier.

2-3. Common base small signal amplifier

Function: wideband small signal voltage amplification

Working principle: Q1 to a common-base configuration single-tube amplifier, R1,R2 provides a base bias voltage, R4 stable operating point, R3 for the collector load resistance. R5 is the load, R6 is the internal resistance of the signal source.

The change of the source voltage caused the change of IE in Q1, which caused the IC to change, after R3 conversion to VCE change, through C2 ac coupling change voltage output to R5.

Normal operating conditions: Q1 in the amplification area, measuring the Q1 of the collector voltage of about 6V.

Debugging method: Adjust the Resistance R1, measure the Q1 's collector voltage to 6V.

Measurement parameters:

1) measuring the end voltage of the signal source VS,Q1 emitter AC voltage VI, Resistance R5 ac voltage VO, calculated voltage gain AV and source voltage gain AVS.

2) measure the phase difference between the input signal and the output signal.

3) Increase the frequency of the input signal, the input voltage is constant, when the output signal amplitude is reduced to 0.7 times times the low frequency when the input signal frequency is recorded, so that the pass-band BW.

4) Increase the input signal amplitude and measure the output signal, and record the input signal and output signal amplitude when the output signal starts clipping.

5) measure the power input current and calculate the efficiency of the amplifier.