Note: This page has been translated by MathWorks. Click here to see

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

Model mixer in RF systems

**Library:**RF Blockset / Circuit Envelope / Elements

The Mixer block performs signal frequency translation and nonlinear amplification.

For a given RF input signal, *V*_{RF} = *A*_{RF}cos(*ω*_{RF}t) and an LO input signal *V*_{LO} = *A*c_{LO}cos(*ω*_{LO}t), the mixer multiplies the signals at the input ports:

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

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 Jürgen Lindner. “Polynomial Model
Derivation of Nonlinear Amplifiers.” *Department of Information
Technology*, University of Ulm, Germany.