Design and Analysis of Digital Feedback Loop AGC for WiMAX 802.16m Receivers

A novel digital feedback loop Automatic Gain Control (AGC) is presented for Worldwide Interoperability for Microwave Access (WiMAX)receivers in this work. The proposed digital AGC design is capable of simultaneously governing two Variable Gain Amplifier (VGA`s)for coarse gain of 24 dB each and one for fine gain of 1 dB. The resultant overall dynamic range of the digital AGC is 80 dB. The proposed design utilizes a lookup table feedback technique to achieve faster response, they're by bringing agility and stability to the system. The proposed digital AGC has a settling time of 0.5 μsec and Error Vector Magnitude (EVM)less than 5%. The digital AGC algorithm is validated on MATLAB-SIMULINK tool and results are tabulated for 64-Quadrature Amplitude Modulation-Orthogonal Frequency Division Multiplexing (64-QAM-OFDM)modulated signals.