Voltage amplification, current amplification, mutual resistance amplification, mutual conductance amplification

Input resistance (viewed from the input end, excluding signal source resistance); output resistance (viewed from the output end, excluding load resistance) R=U/I

Passband (mid-frequency band) reflects the degree of amplification of signals of different frequencies by the amplifier circuit.

nonlinear distortion

Maximum undistorted output voltage (at the static operating point, the "AC voltage" that does not distort the output waveform)

signal-to-noise ratio, noise figure

Core active devices

Bias circuit (circuit that sets the static operating point)

coupling circuit

The functions of power supply Vcc: 1. Provide bias voltage to ensure that the transistor works in the amplification area. 2. Provide energy

Static Q point is suitable

Dynamic signals can be transmitted normally

For practicality: common ground, as little DC power supply as possible; no DC component on the load

DC path

communication path

Static analysis [find two intersection points]

dynamic analysis

Draw DC path

Calculate UBE. If it is less than UBE (on), it is in a cut-off state (the transistor is regarded as open circuit); if it is not cut off, assume the amplification mode, analyze the input loop and output loop respectively, and estimate UCEQ. If it is greater than UCES, it is in amplification mode; Otherwise, in saturation mode, UCEQ=UCES, recalculate IC

Draw the communication path (known Q point)

Use the slightly variable equivalent circuit model to replace the triode to get the AC equivalent circuit. (First equate be to rbe, and then equate ec to controlled current source) (Current reference direction b to e, c to e)

Calculate slightly variable parameters rbe, rce

Analyze AC indicators Au, Ri, Ro (pressure resistance method, replace the load with a voltage source, and the signal source is short-circuited)

Partial pressure method (UBQ)

Thevenin equivalent (equivalent to the transistor input port, split VCC, and draw it as a grounded power supply to facilitate analysis of open circuit voltage and equivalent resistance)

The relationship between the two (when Rb<<(1 b)Re, Thevenin equivalent method can be simplified to the partial pressure method)

common hair

Collect together

Common base