Interface between SAW filter and Gilbert cell mixer

摘要

The invention concerns multipliers used to modulate a carrier by a signal. The signal is delivered by a Surface Acoustic Wave (SAW) filter, which requires a load impedance of low value, in the range of tens of ohms, and almost certainly less than 200 ohms. The invention modifies a Gilbert multiplier such that its signal-input stage presents the required load impedance to the SAW. The input impedance of the signal- input stage is adjustable.