Synthesis of low-spur GHz sinusoids using a 4-bit D/A converter

This work reports a method of digitally synthesizing sinusoidal waveforms at GHz frequencies with low spurious content. This is accomplished with a 4-bit D/A converter and a logic sequencer that is driven by a digital clock. A circuit using this method was implemented and tested at frequencies as high as 2.7 GHz. A spurious free dynamic range of 84 dB was measured at 2.3 GHz. This is thought to be significant because of the high operational speeds achieved along with the inherent simplicity of the circuit.