Low Power Variable gain amplifier with Bandwidth of 80300 MHz using for Sigma-Delta analogue to digital converter in Wireless Sensor Receiver

Abstract

Variable-gain amplifier (VGA) is one of the basic building blocks of many communication systems. In this paper we present a novel structure of VGA with 22 db of gain range and 220 MHz of bandwidth frequency variation. This circuit combines a voltage to current (V-I) converter and two-stage CMOS amplifier to achieve programmable gain and bandwidth .The gain is varied by changing the input voltage (V in) from-1V to 0V. The maximum bandwidth is about 300 MHz. The gain can be varied from 38 dB to 60 dB in 1 dB gain steps. The overall circuit draws current from 10µA to 150µA at ±1.5V power supply. The noise figure of the system at maximum gain is 18dB, and the third-order intermodulation intercept point (IIP3) at minimum gain is-8 dBm. Simulations results with static and dynamic behaviour is presented and validated with the technology AMS 0.35µm. Eventually we have also succeeded in reducing the static power consumption to 0.5 mW.