A low power high gain gain-controlled LNA + mixer for GNSS receivers

Abstract

A low power high gain gain-controlled LNA + mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNA + mixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNA + mixer, a previous low power LNA + mixer, and the proposed LNA + mixer are presented. The circuit is implemented in 0.18 μm mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2 and consumes 2 mA current under 1.8 V supply.