A Ku-Band CMOS Power Amplifier With Series-Shunt LC Notch Filter for Satellite Communications

This article presents a Ku-band power amplifier with a series-shunt LC notch filter in 65-nm CMOS. The notch filter is integrated into the inter-stage matching network to attenuate the receiver-band noise, thereby reducing transmitter-to-receiver interference. A comprehensive analysis of the series and the shunt notch filters, as well as the position to apply the notch filter is discussed. Besides, a systematic method of optimizing passive devices in the notch filter is proposed to further improve network Q and minimize the influence on the power amplifier. Fabricated in 65-nm CMOS technology, the power amplifier prototype delivers a measured gain of 21.9 dB with 3-dB bandwidth from 13.7 GHz to 16.7 GHz at the nominal state. At 14.2 GHz, it can offer a saturated output power of 14.5 dBm with peak power added efficiency of 24.1%. The notch frequency is adjustable from 10.3 to 11.9 GHz to offer the best attenuation at the receiver band. From 10 to 12 GHz, a maximal attenuation of 30 dB is achieved. The design occupies a core area of 0.35x0.85 mm(2).