Playing with diode modulators...

Author: Wolfgang Scherr
Date: 13th March 2021

All rights reserved. For educational purposes only.


One day I stumbled over this web link about modulator circuitries (external link).

Instead of playing games, why not once playing with circuit simulators?

So I thought it is fun to try this examples in SystemC-AMS ELN using the piece-wise linear sources already available in the actual proof of concept library.

First, I build some basic blocks, afterwards I use them for the modulators. Have fun trying them yourself!

Elements for the circuits with basic tests

Low pass and high pass filter models

SystemC-AMS source code:

LC lowpass: H - CPP - (TB) CPP

LC highpass: H - CPP - (TB) CPP

AC simulation result:

Diode model

SystemC-AMS source code:

Diode: H - CPP - (TB) CPP

DC plot generated from a transient simulation using a voltage ramp:

Modulator circuits

We can now use the elements previously defined:

Single diode modulator

SystemC-AMS source code:

Single diode mixer: H - CPP - (TB) CPP

Transient plot of the modulated RF signal:

Some spectrum plots of this circuitry and detailed measurements:

Extracting some relevant data:

residual LO power: -16.914084444603873 dBm
residual IF power: -64.19823692613629 dBm
USB power: -30.604073286470598 dBm
LSB power: -30.622226575057244 dBm
LO input power 9.999999999999996 dBm
IF input power -10.000000000000597 dBm

More to follow...