Design and Analysis of a 94-GHz CMOS Down-Conversion Mixer With CCPT-RL-Based IF Load

Abstract

A low-power W-band gain-enhanced CMOS down-conversion mixer for millimeter-wave-to-baseband pulsed-radar receiver is presented. To enhance the equivalent load impedance while keeping the transconductance ( $\text{g}_{\mathrm {m}}$ ) of the RF $\text{g}_{\mathrm {m}}$ stage unchanged and achieving prominent IF bandwidth, we propose a novel core IF load, which is based on the parallel combination of the cross-coupled PMOS transistors (CCPT) and the series RL circuit (i.e., CCPT-RL-based core IF load). The down-conversion mixer comprises a double-balanced Gilbert-cell-based mixer core with an inductive-peaking current-bleeding RF $\text{g}_{\mathrm {m}}$ stage and a CCPT-RL-based core IF load, two elliptic baluns, and a source follower buffer. Compared with the traditional down-conversion mixer for direct conversion receiver, conversion gain (CG), and noise figure (NF) can be significantly enhanced. For 88~100 GHz, the mixer consumes 5 mW and achieves excellent RF-port input reflection coefficient ( ${S}_{11}$ ) of −9.6~−19.1 dB and LO-port input reflection coefficient ( ${S}_{22}$ ) of −5.5~−21.9 dB. In addition, the mixer achieves excellent CG of 11.8~14.6 dB, NF of 14.2~15.2 dB, and LO-RF isolation of 34.6~35.3 dB–one of the best CG, NF, and LO-RF isolation results ever reported for a W-band down-conversion mixer.