A broadband high linearity down-converter for GNSS receiver applications

A broadband high linearity down-converter for the safety-of-life receivers of Global Navigation Satellite System (GNSS) is presented. The proposed novel down-converter with high linearity and high driving ability, consists of a broadband common-gate low-noise transconductance amplifier (CG-LNTA), a current-driven passive mixer and a high linear impedance driving amplifier. To improve the wideband input matching of 1.15-1.65 GHz and all-band GNSS signal reception, a CG-LNTA with gm-boosting technique of capacitor cross-coupled (CCC) is employed. To drive a 50-Ω low-impedance load and achieve excellent linearity performance, a novel bridge mode transimpedance driving amplifier with variable gain is proposed. Measurement results show that the proposed down-converter achievers +38 dBm output 3rd order intercept point (OIP3), +17 dBm output-referred 1 dB compression point (OP_{1 dB}), 10-27 dB variable gain, and less than 12.6 dB noise figure (NF). With high linearity, low noise and sufficient driving capability in low conversion gain mode, the proposed down-converter is suitable for reliable GNSS receiver in complex environments.