Class A amp LTspice Model

Class A Amplifier from Experimental Methods in RF Design (EMRFD) Fig. 2.29.

I found a way in LTspice that you can simulate several signal drive levels to give various output waveforms.

Here the graphic shows at 20mV AC drive a nice sinusoidal O/P on the collector. As we increase the drive level the transistor goes into saturation and the output wave form appears clipped as the collector voltage appoaches the Voltage supply at 10V and thus the causing the collector curent to drop to zero. At the exteme input drive level the collector has dropped below the base voltage and the transistor is shown saturated for the bottom part of the curve.

It was nice to model an amplifier this way to show the effect of non-linearity behavior. The Spice models shown are similiar to the curves shown in EMRFD Fig2.30.


The spice model includes a Spice directive that basically switches in each voltage source given by the .param and .step function. The B1 symbol is an arbitary behavioural voltage source symbol and not a voltage source symbol which caught me out.