A Monolithic CMOS Realization of the Double-Quadrature Image-Reject Weaver Receiver

This work presents a fully-integrated double-quadrature Weaver receiver for monitoring the NIST time and frequency reference radio station WWV across multiple channels in the 2.5–20 MHz range. The design takes advantage of the Weaver architecture's elimination of image rejection filters. The receiver uses a broadband low-noise amplifier (LNA) with an input-referred noise power spectral density (PSD) of < 2.25 nv/Hz
^1/2
for high sensitivity. Instead of large filters, a double-quadrature down-conversion process is used to remove the image signal. Both local oscillators (LOs) are frequency- and phase-locked to each other via an on-chip frequency divider, and their I and Q components are generated by highly-precise digital phase splitters. The receiver was fabricated in the TSMC 180 nm CMOS process and consumes 24.9 mW. Measurements show in-band gain > 40 dB, noise figure (NF) < 2.9 dB, and maximum image rejection ratio (IRR) of 29 dB without calibration.