A monolithic audio spectrum analyzer

A monolithic audio spectrum analyzer with 16 channels of bandpass filters, half-wave rectifiers, and postfiltering has been fabricated with double-poly NMOS technology. The chip was designed using switched-capacitor filter techniques. It performs a total of 84 poles of filtering and contains 100 operational amplifiers in an area of 225 × 280 mils. A system dynamic range of better than 43 dB, linearity of better than 1 percent, and center frequency accuracy of better than 1 percent have been achieved.