A low-power AGC with level-independent phase margin

We describe a 32-/spl mu/W 77dB-dynamic-range power-law-compression VLSI AGC circuit for use in audio applications particularly for hearing aids and cochlear implants. We demonstrate that in spite of the nonlinearities in the circuit, the feedback-loop phase margin is invariant with input level. This ensures that robust performance at one level guarantees robust performance at any level.