A ROM-Less DDS Using Pseudo-Sine Generator

This paper describes a memory-less direct digital synthesizer (DDS) using a pseudo-sine generator. This DDS uses an analog pseudo-sine generator to directly generate a sine wave from the accumulator output ramp-like wave. Since the conventionally used complement circuit for generating a triangular wave is not required, this configuration is suitable for reducing the circuit scale of the digital block and reducing power consumption. The proposed configuration of the pseudo-sine generator with a replica digital-to-analog converter (DAC) makes unnecessary of voltage adjustment in the analog circuit and has high tolerance to process, voltage, and temperature (PVT) variations. A DDS prototype combining discrete components has been verified to significantly reduce non-harmonic spurious signal levels below the phase accumulator overflow signal.