Flat-High-Gain Design and Noise Optimization in SiGe Low-Noise Amplifier for S–K Band Applications

Abstract

This paper presents an ultra-wideband (UWB) low-noise amplifier (LNA) with extremely flat-high-gain and low-noise figure (NF). In traditional resistive feedback topology, input matching, gain, and NF cannot be balanced. For better performance trade-offs in UWB design, a novel emitter-follower resistive feedback (EFRFB) is introduced, which utilizes a common-collector amplifier followed by a feedback resistor to flatten the gain (the ripple reduced by 2.3 dB) while alleviating the constraints between the gain and input matching. The enhanced gain without restraint by S11 is exactly required for noise reduction technology. Moreover, a peaking inductor and two resistors are adopted to improve bandwidth and output matching, respectively. The proposed LNA is implemented in a 0.18-μm SiGe BiCMOS technology and occupies 0.15 mm2 without pads. Measurements demonstrate that the LNA has a gain of 19.5 dB with ripple < 0.6 dB, a minimum NF of 2.8 dB from 2 to 22 GHz, and an input third-order intercept point (IIP3) of–7.6 dBm at 10 GHz while drawing 10.9 mA from a 3.3 V supply.