94 GHz eight-way power amplifier with high output power and power-added efficiency in 90 nm CMOS

Abstract

A four-stage eight-way CMOS power amplifier (PA) for 94 GHz radar sensor is reported. The PA constitutes a common-source (CS) input stage, a CS first gain stage, a two-way CS second gain stage, followed by an eight-way CS output stage using miniature triple Y-shaped divider and combiner. Broadband π-match input, inter-stage, and output networks are adopted for broadband impedance or power matching. Inductive shunt-shunt feedback technique is used at the input and the first gain stages to boost gain. This leads to a boosted saturated output power (Psat) and power-added efficiency (PAE). At every division’s input (i.e. the drain of the parallel CS output stage), the triple Y-shaped current combiner transforms the serial RL load into the optimum load impedance (homologous to the optimum Psat and PAE) of the output stage transistors. At supply voltage (VDD) of 1.2 V, the PA attains Psat of 12.1 dBm, gain of 17.5 dB, and PAE of 14.8% at 94 GHz, the best values ever demonstrated for a W-band CMOS PA in 90 nm CMOS. Moreover, at high VDD of 2.4 V, the PA achieves high Psat of 18.2 dBm, gain of 19.6 dB, and PAE of 15% at 94 GHz. The eminent results of the CMOS PA reveal that it is hopeful for 94 GHz radar sensor.