A 3-to-5GHz UWB LNA with a Low-Power Balanced Active Balun

摘要

A 3-to-5GHz ultra-wideband (UWB) low-noise amplifier (LNA) with a low-power balanced active balun aiming at IEEE 802.15.4a (Band Group 1) compliance is presented. The LNA employs an NMOS feedback for wideband input matching, and current reuse scheme for reducing power consumption. The active balun uses a differential amplifier with a cascoded cross-coupled pair to provide 6dB gain as well as to mitigate the gain and phase imbalances. The proposed fully integrated LNA and balun achieve noise figure of 3.6dB, S21 of 30dB, and HP3 of -24dBm (-12dBm for LNA core) from 3GHz to 5GHz. The maximum gain and phase mismatches of the balun from 0.5GHz to 10GHz are 0.4dB and 1.8°, respectively. It consumes 19mW from 1.2V supply; 8mW for the LNA, 2.5mW for the active balun, and 8.5mW for the buffer.