Highly Linear and Very Low-Noise Down-Conversion Mixer for Extracting Weak Signals in the Presence of Very Strong Unwanted Signals

摘要

A highly linear and very low-noise down-conversion mixer for extracting weak signals in the presence of very strong unwanted signals is disclosed. Aspects of an embodiment may include a source follower circuit in a transmitter front end of a mobile terminal. The source follower circuit may receive RF signals prior to the RF signals being amplified by a power amplifier for transmission. The RF signals may comprise in-phase and quadrature components. The source follower circuit may generate output RF voltage signals, and communicate the output RF voltage signals to a switching circuit via a coupling capacitor. The switching circuit may down-convert the communicated output RF voltage signals to generate differential baseband signals. The capacitance of the coupling capacitor may be changed to change gain and/or linearity of the differential baseband signals. Each of the differential baseband signals may be low-pass filtered to attenuate higher frequencies.