Programmable sine wave generator employing a mismatch-shaping DAC

A programmable signal generator is described along with some experimental results. The generator may be used as the reference of a PLL frequency synthesizer. It consists of a digital band-pass sigma-delta oscillator and a low-resolution D/A converter employing a dynamic element-matching algorithm. The prototype uses an inexpensive, untrimmed analog circuit to provide a variable frequency sinusoid in the MHz range with 92 dB of SFDR. The hardware complexity of both the analog and digital circuits is smaller than an equivalent DDS-based generator.