Ka-band calibration-free high image-rejection up/down mixers with 117% fractional IF bandwidth for SATCOM applications

This paper presents two Ka-band calibration-free up/down mixers, each with high image rejection ratio (IRR) for a wide band of IF frequencies covering the satellite modem frequency range (0.95-2.15 GHz). To achieve broadband IRR > 30 dBc, a 3-stage castle-wall polyphase filter (PPF) is used at the IF port to minimize the amplitude and phase errors (AM < ±0.2 dB, PM < ±1^◦). For local oscillator (LO) quadrature generation, a four-way quadrature divider composed of two broadside 90^◦ couplers and one Marchand balun is used. The single-sideband (SSB) up mixer shows a 4.2-dB conversion gain (CG) with LO power of 4 dBm and an output 1-dB gain compression (OP_1dB) of −4.3 dBm. The image-rejection (IR) down mixer achieves a −11.6-dB CG under LO power of 5.5 dBm and an input 1-dB gain compression (IP_1dB) of 0 dBm. With a 1.2-V supply voltage, the SSB up mixer and IR down mixer consume 15.6 mW and 12 mW, respectively. The SSB up mixer and IR down mixer demonstrate broad IRR bandwidths at the IF frequencies (IRR > 30 dBc) from 0.6 to 4 GHz (148% fractional IF bandwidth) and from 0.65 to 2.5 GHz (117%), respectively, with no calibration. In addition, the RF bandwidths (IRR > 30 dBc) of the SSB up mixer is 27.7-33.3 GHz (18.36% fractional RF bandwidth), and the IR down mixer is 17.1-20.6 GHz (18.5%). The IRR performances are robust against process, voltage, and temperature (PVT) variations and Monte Carlo simulations for satellite communication (SATCOM) applications.