Analysis and Design of a 0.6- to 10.5-GHz LNTA for Wideband Receivers

A low-noise transconductance amplifier (LNTA) for wideband receivers based on a g_m-boosted current mirroring topology that operates over 0.6- to 10.5-GHz is presented. g_m boosting relaxes the G_m and S₁₁ bandwidth (BW) tradeoff and the noise figure (NF) and input matching tradeoff. The active feedback synthesizes a second-order input impedance profile that further extends the S₁₁ BW. Despite the high G_m obtained over large BW, high linearity is maintained through the predistortion inherent in the current mirroring topology. The LNTA is used in a 65-nm CMOS wideband channelizing iterative downconversion receiver targeting spectrum and signal analysis for cognitive radio and performs active signal splitting across two paths with a total postlayout simulated G_m of 242 mS (170 and 72 mS in paths 1 and 2, respectively). S₁₁ BW and G_m BW both exceed 10.5 GHz. Minimum LNTA NFs simulated in the two paths are 4 and 4.8 dB, respectively. Simulated wideband IIP3 and blocker P1dB are +6 and +1.5 dBm, respectively. Measurements of a direct conversion receiver in path 2 closely match simulations.