Passive mixer having transconductance amplifier with source degeneration capacitance

[0025]This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description.

[0026]A current-mode passive mixer 300, 800, 900 with conversion gain that is independent of process, voltage, and temperature (PVT) variation is described below, with reference to FIGS. 3-9. Optionally, the conversion gain may be programmable. Using this technique, the conversion gain of the current-mode passive mixer 300, 800, 900 is proportional to the ratio of the source degeneration capacitance CS to the load capacitance CL. Thus, although the absolute capacitance and other circuit parameters vary with PVT, the ratio of the source degeneration capacitance CS to the load capacitance CL is independent of PVT variation, and so is the mixer conversion gain. In particular, if CS and CL are of the same type of construction, then both are assured to vary in the same manner together in response to any ...