A low voltage VGA for RFID receivers

RFID is a worldwide attractive technology for reliable wireless communication system. Automatic gain control system of such devices is very important which is performed by Variable Gain Amplifier (VGA). In this paper, a class AB VGA, consisting of a linear transconductor amplifier and a linear transimpedance amplifier, is designed and simulated in CEDEC (software for design and simulation of ICs) 0.18-µm CMOS process for low power and high speed RFID receivers. The simulation result show that, the proposed VGA has a wide bandwidth of 100 MHz and dissipates power less than 125uW at 1V supply voltage. From the results it is also apparent that the circuit is capable of working with high linearity and wide bandwidth. Good frequency response (Gain) and the wide bandwidth of this class AB VGA makes it suitable for low power RFID receiver transceivers.