High Dynamic Range Low Power Drive Quadrature Millimeter-Wave Demodulator

Abstract

This paper presents a novel demodulator implemented using a broadband six-port circuit and power detectors. Every single detector uses a pair of parallel Schottky diodes and a 90° hybrid coupler to improve the input match. The V-band demodulation results of the proposed six-port interferometric receiver are presented in a wide range of the local oscillator (LO) power. The detected baseband I/Q measurements results are quasi-linear over the considered LO power from 0 to − 40 dB. Moreover, the high-power drive is not required as in the case of conventional diode mixers. Real time Error Vector Magnitude (EVM) measurements of pseudorandom QPSK sequences are performed using a Vector Signal Analyzer. The results are around 5% over a LO power range of 35 dB. This performance demonstrates the capability of the quadrature interferometric mixer in direct demodulation using low LO power. The proposed circuit is well suited for millimeter-wave wireless communication systems and it can replace conventional mixers in efficient and low-cost homodyne receivers.