Error performance of subsampling digital power estimation for integrated receivers

Abstract

Estimation of signal power levels at the output of integrated receiver building blocks is a vital function as the block voltage or power gains are set based on sensed power levels to maintain constant levels at block outputs in the receiver chain. RF and IF level real-time gain settings are determined with Automatic Gain Control (AGC) loops. AGC loop circuit topologies are usually based on analog detection circuits. These analog power detection circuits are based on techniques such as envelope detection, and logarithmic amplification usually accompanied by severe accuracy issues such as Process, Voltage and Temperature (PVT) spreads preventing correct gain adjustments. Adopting a dominantly digital approach to detect the signal power would ensure a significant reduction in PVT spreads. This work presents a review of the subsampling digital power estimation to create low power digital power estimations alternative to analog methods. The simulations of the method are applied to an AM and a 64-QAM signal. Simulation results show that the power estimation error is within the acceptable level of +/- 1 dB.