5–6 GHz CMOS low-noise direct conversion receiver using a differential RF VGA with a differential inductor load

A low-noise low-power direct conversion receiver with a differential RF VGA is demonstrated using 0.18um CMOS technology. A topology that uses a differential inductor load for a differential RF VGA is employed for the single-to-differential conversion. Since the common-mode rejection ratio of a differential variable gain amplifier is increased by the mutual magnetic coupling in a differential inductor load, this work achieves noise floor less than 5 dB covering the 5–6 GHz band. Moreover, the conversion gain is around 50 dB and the total current consumption is 4.75 mA at 1.8 V supply voltage.