Abstract: A programmable frequency synthesizer (PFS) consists of three serially conted stages: an accumulator, a triangle converter, and a sine shaper. The accumulator is the frequency-generating stage of the synthesizer. It consists of an input latch to store the binary programmed frequency, an adder, an output latch to store the output of the adder, and a clock oscillator. The output frequency of the accumulator can be directly scaled by changing its clocking frequency. The square wave output of the accumulator is divided in frequency by the triangle converter, which produces a triangularly shaped staircase waveform. The sine shaper stage employs diode limiters and filters to produce low-harmonic sinusoids from the triangular staircase.