A K/Ka-Band Switchless Reconfigurable 65 nm CMOS LNA Based on Suspended Substrate Coupled Line

Abstract

This article presents a K/Ka (18-40) GHz dual-band switch-free reconfigurable 65nm CMOS Low-Noise Amplifier (LNA) realized by inter-stage and output-stage Suspended-Substrate Coupled-Lines (SSCL) for the first time to the author’s best knowledge. The amplified input signal from the broadband drive stage is divided into two parallel single band stages by the proposed inter-stage SSCL. Two split-band signals are amplified by the corresponding High-band (Ka) and Low-band (K) stages. The proposed output-stage SSCL combines the amplified two single-bands at the output. The proposed SSCL also provides the required network matching to the LNA. The single band of operation can be achieved by simply turning off the unused transistor band’s drain voltage. The proposed LNA achieves a maximum noise figure (NF) taken in dual-mode of 1 dB and 1.2 dB and a gain of 27 dB with 0.2 dB and 2 dB variation in the K-band and Ka-band, respectively. Statistical analysis and design of experiment (DoE) are applied to predict the percentage error tolerance and validate the contribution of the parameters towards gain, return loss, and noise figure. This LNA exhibits an input and output 1-dB compression point (IP1dB & OP1dB), third-order input & output intercept point (IIP3 & OIP3) of −17/−16 dBm, +7.1/6.4 dBm, 0 dBm and +25/+23 dBm over 18-24/25-40 GHz respectively. The fabricated LNA draws 21.4 mA from 1.2 V with a size of 0.61 $\times $ 0.92 mm2.

Keywords

• Suspended substrate coupled lines (SSCL)
• low noise amplifier (LNA)
• CMOS
• K-band
• Ka-band