Numerically-controlled oscillator with dithered coarse and fine splitter

A numerically-controlled oscillator (NCO), comprising:

• a phase accumulator (PA) having a first input adapted to receive a phase increment, a second input adapted to receive a clock signal, and third input adapted to receive a reset signal, the PA operable to provide an instantaneous phase at an output;
• a sequence generator operable to provide a pseudo-random binary sequence (PRBS) at a PRBS output;
• a binary adder having a first input coupled to the output of the PA and having a second input coupled to the PSBR output, the binary adder operable to add the PRBS and the instantaneous phase and provide a resulting sum at an adder output;
• a truncator having an input coupled to the adder output and operable to truncate at least one least significant bits of the resulting sum to provide a dithered course phase at a truncator output;
• and
• a binary subtractor having a first input coupled to the PA output and having a second input coupled to the truncator output, the binary subtractor operable to subtract the dithered course phase from the instantaneous phase to provide a dithered fine phase at a subtractor output;
• and
• a polynomial approximation unit having a first input coupled to the truncator output and a second input coupled to the subtractor output, the polynomial approximation unit operable to provide a sequence of values representing a discrete sinusoidal signal.

A method of generating a sinusoidal signal, comprising:

• receiving a phase increment, a clock signal and a reset signal;
• providing an instantaneous phase by a phase accumulator (PA);
• adding a pseudo random binary sequence (PRBS) and the instantaneous phase and providing a resulting sum;
• truncating at least one least significant bits of the resulting sum and providing a dithered course phase;
• subtracting the dithered course phase from the instantaneous phase and providing a dithered fine phase;
• and
• providing a sequence of values representing a discrete sinusoidal signal using a polynomial approximation, the dithered course phase and the dithered fine phase.