A Digitally-Controlled Variable-Gain Amplifier for Ultra-Wideband Applications

Introduction Ultra-wideband (UWB) technology is a promising solution for low-complexity, low cost, low power and high-data rate wireless connectivity among devices in a personal area network. The main signal processing operations involved in a typical analog front end of a UWB receiver before demodulation are frequency translation to baseband, signal amplification and filtering to strengthen the received signal and eliminate interference. The required amplification depends on the strength of the incoming signal. This mandates a wideband variable gain amplifier (VGA) with wide controlled-gain range. The design of a VGA poses challenging constraints such as bandwidth, tuning range, dc offset, dynamic range, etc. Our design demonstrates bandwidth of approximately 900 MHz with a 31.5 dB linear-controlled gain range. Moreover our design uses a novel digital control scheme based on binary weights to control the gain of the VGA.