Digitally-Controlled Variable-Gain-Amplifier Based on Current Conveyor with Opamp and Inverters Only

This paper presents a new topology of a Digitally-Controlled current-mode-Variable-Gain-Amplifier "DCVGA". A fully differential DCVGA is proposed, which improves the VGA performance. The proposed circuit is based on the current conveyor cell reported in [1]. The circuit is suitable for low-power low-voltage applications since it is based on CMOS inverters. The proposed DCVGA achieves linear-in-dB gain variation at 1dB resolution. The variable gain is tuned from -5 to 36 dB. The proposed circuits have been designed and simulated using 0.13 mu m IBM CMOS process. The simulation results show good performance in both gain-tuning ability and frequency response. Also, the 3-dB bandwidth is about 50 kHz at maximum gain. The power dissipation is 2.1mW from 1.5V supply voltage.