A Broadband dB-linear VGA with third-order interleaving active feedback

This paper presents an inductorless variable gain amplifier (VGA) in a standard 65 nm CMOS technology for mul-ti-GHz wideband applications. Designed with a cell-based method, the VGA provides an accurate dB-linear gain characteristic. By adopting the gate peaking technique and a third-order interleaving active feedback, the VGA bandwidth (BW) is further extended. The simulated result shows a -3 dB bandwidth in excess of 4.5 GHz. The gain can be varied from 2.7~30.2 dB with a dB-linear gain range of 17.5 dB. At maximum gain stage, the input P -ldB is -36 dBm with noise figure (NF) of 17.9 dB. While at minimum gain stage, the input P -ldB and NF are -7.3 dBm and 23.5 dB respectively. The circuit consumes 6.6 mA through a 1.2 V supply and occupies 0.0286 mm2active area.