A programmable switched-capacitor sinewave generator

A new switched-capacitor topology is presented to realize a sinewave generator. The circuit architecture is simple and is suitable for monolithic realization. The peak amplitude as well as the frequency of the sinusoid are digitally programmable. The frequency is independent of circuit parameters, and it depends directly on the clock frequency and thus provides stability as well as accuracy. Stability in the peak amplitude is provided by a stable external dc source. Breadboard testing of the circuit has given harmonic distortion of less than 35 dB with /spl plusmn/5% capacitors. Distortion has been reduced to less than 45 dB when the capacitors are adjusted closer to the design values.