A low-power time-multiplexed switched capacitor speech spectrum analyzer embodying several novel circuit designs is described. Expressions for errors that limit the accuracy of the running spectrum are derived. An experimental four-channel (three active and one zero-input channel) speech-spectrum analyzer has been fabricated using a 5-μm double-polysilicon CMOS process. The largest DC offset difference of the BPF (bandpass filter) section in a given chip is typically 8 mV (for five chips), representing a difference error of 0.003% for a 1-V peak signal. These measurements demonstrate that, by careful biquad design, the DC offsets between different BPF section channels within a chip and their corresponding difference errors can be made small.