A PVT-Tolerant >40-dB IRR, 44% fractional-bandwidth ultra-wideband mm-Wave quadrature LO generator for 5G Networks in 55-nm CMOS

Precise generation of quadrature signals over a
wide frequency range is a key function for the next-generation
5G communication systems. In this paper, we present a wideband
quadrature generator based on a single-stage polyphase
filter (PPF). A phase detector senses the phase error from
quadrature signals generated by a single-stage PPF, and a
feedback circuit continuously tunes the filter center frequency to
the input signal frequency by varying the polyphase resistance of
an nMOS device in triode. Transformer-based resonant circuits
at the input and output of the PPF ensure wide bandwidth
and low loss. Prototypes have been realized in a 55-nm CMOS
technology. Tailored to the next-generation 5G systems for crossnetwork
interoperability requirements, the measured quadrature
generator shows an image rejection ratio IRR > 40 dB over a
bandwidth from 28 to 44 GHz. The power consumption is 36 mW
for the PPF and buffers, and 3 mW only for the calibration
loop. One key aspect of the proposed solution is its robustness
over process, voltage and temperature (PVT), one of the weak
aspects of alternatives proposed in the literature. This solution
compares favorably with the state of the art and shows the largest
fractional bandwidth (44%) among the quadrature generators at
frequencies greater than 20 GHz, to authors’ knowledge.