Model mixer in RF systems

**Library:**SimRF / Circuit Envelope / Elements

The Mixer block performs signal frequency translation and nonlinear amplification.

For a given RF input signal *V _{RF}* =

$$\begin{array}{c}{V}_{in}{V}_{LO}={A}_{in}\mathrm{cos}\left({\omega}_{in}t\right){A}_{LO}\mathrm{cos}\left({\omega}_{LO}t\right)\\ \frac{{A}_{in}{A}_{LO}}{2}\mathrm{cos}\left[\left({\omega}_{in}+{\omega}_{LO}\right)t\right]+\frac{{A}_{in}{A}_{LO}}{2}\mathrm{cos}\left[\left({\omega}_{in}-{\omega}_{LO}\right)t\right]\end{array}$$

This mixing converts the frequency of RF signal
to *ω _{RF}* +

The Power gain specification for this block relates the power of a single-sideband (SSB) to the input.

After mixing the RF and LO signals, the mixer block performs
amplification. To model linear amplification, the mixer scales the
signals by the coefficient a_{1}.
A Voltage Controlled Voltage Source (VCVS), specified with a polynomial,
implements nonlinear amplification. The polynomial includes saturation
automatically and produces additional intermodulation frequencies.

[1] Grob, Siegfried and Lindner, Jurgen, "Polynomial
Model Derivation of Nonlinear Amplifiers", *Department
of Information Technology*, University of Ulm, Germany.

Was this topic helpful?