Automatic Gain Control (AGC) is currently used in conventional systems where an input signal is expected to fluctuate in power. In some conventional systems, AGC is used to compress a vast dynamic range of a received signal to fit into an input range of a downstream device, such as an analog-to-digital converter (ADC), thereby avoiding saturation and helping to ensure that a signal-to-quantization-noise ratio at the output of the ADC is acceptable. In some conventional devices, a goal of AGC is to provide a signal with a substantially constant average power for successive functional blocks. AGC can be used to make a receiver somewhat insensitive to signal power variation.
AGC is usually performed with an amplifier provided near the input of a receive signal path. The amplifier is controlled by feedback loop control logic that measures signal strength somewhere along the receive signal path and passes control signals back to the amplifier. However, for some systems that have digital and frequency domain components in the signal path, a single, analog amplifier near the signal input may not provide adequately robust AGC.