Adaptive automatic gain control using hybrid gamma parameters for frame-based OFDM receivers

Automatic gain control (AGC) is very essential to frame-based orthogonal frequency division multiplexing (OFDM) receivers, because the significant features of OFDM signals are large dynamic range and high Peak-to-Average power Ratio (PAR). This paper proposes an adaptive strategy, which employs flexible gain compensation scheme with hybrid gamma parameters to improve the convergence speed and at the same time maintains the stability of AGC circuits. In order to find the adaptive parameter-changing-point, a new scheme employing a programmable absolute power deviation reference is introduced. At the same time a number of 1-bit buffers are added to reduce the amount of jitter during the gain tracking process. Finally, the performance of the proposed adaptive AGC strategy is discussed by simulation.