Adaptive filters suitable for real-time spectral analysis

New cascade structures for adaptive filters are presented. They are especially suitable for real-time applications. Since the new structures are intended to be realized using single-chip DSP ICs or single-chip custom VLSI circuits, the requirements for memory and divisions are minimized. The new structures are based on state-variable biquads that in addition to having good SNRs and low sensitivities (for fixed-point implementations) can also have their resonant frequencies and Q-factors independently tuned. The special cases of using the adaptive filters for tracking sinusoids corrupted by noise and for formant based speech compression are described in detail.