# Nonlinear BJT Mixer

### Single Ended BJT Mixer(Nonlinear)

A single ended BJT mixer is shown in Figure 1.

Figure 1. Schematic of a single ended BJT mixer

In active region the BJT is modeled as .

From the Figure 1,

(1)

If , then

(2)

Typically . So is given by

(3)

Substituting in Eq(1),

(4)

In Eq.(4), except term all other terms are near to LO frequency or higher than LO frequency. Therefore they can be filtered out by output filter.

Votlage conversion gain is,