A K-/Ka-Band Broadband Low-Noise Amplifier Based on the Multiple Resonant Frequency Technique

A wideband CMOS low-noise amplifier (LNA) with multiple resonant frequencies is demonstrated in this article. A common source (CS) with inductive degeneration topology is widely employed in LNA circuit design to decouple the input impedance from the noise figure (NF). Since CS with inductive degeneration topology only achieves a single resonant frequency, it generally has narrow bandwidth performance. Through impedance transformation analysis of the matching circuit, a shunt resonator combined with inductive degeneration topology employed for input impedance transformation is carefully constructed to form multiple resonant frequencies. By placing resonant frequencies further apart from each other, impedance fluctuations within a wideband frequency range can be alleviated. In addition, the noise performance of this topology is the same as that of a conventional CS source-degenerated structure. The proposed LNA for the whole K/Ka Band is implemented in a commercial 65-nm CMOS process. It occupies 0.28 mm
²
. Under a 1.0 V voltage supply, the LNA achieves 3-dB gain bandwidth of 28 GHz from 16.5 GHz to 44.5 GHz. Within the whole 3-dB bandwidth, the gain is larger than 15.5 dB, the NF is less than 4.8 dB with a minimal value of 2.72 dB, and the input 1-dB gain compression point (IP
_1dB
) varies from −24 dBm to −12 dBm.