US 12,231,145 B1
Systems and methods for digital signal synthesis with variable sample rate DAC
Tommy Yu, Orange, CA (US); and Avanindra Madisetti, Coto de Caza, CA (US)
Assigned to Mixed-Signal Devices Inc., Irvine, CA (US)
Filed by Mixed-Signal Devices Inc., Irvine, CA (US)
Filed on Feb. 24, 2023, as Appl. No. 18/174,093.
Claims priority of provisional application 63/268,457, filed on Feb. 24, 2022.
Int. Cl. H03M 1/82 (2006.01); H03M 1/06 (2006.01); H04L 27/26 (2006.01)
CPC H03M 1/822 (2013.01) [H03M 1/0626 (2013.01); H04L 27/26412 (2021.01)] 7 Claims
OG exemplary drawing
 
1. A digital frequency generator comprising:
a direct digital frequency synthesizer (DDFS);
a digital-to-analog converter (DAC);
a frequency/phase estimation circuit;
a stable reference clock (REF CLK);
a variable frequency sample clock; and
a frequency control word (FCW);
wherein the DAC is sampled by the variable frequency sample clock;
wherein the DDFS is clocked by the variable frequency sample clock;
wherein the frequency/phase estimation circuit receives as inputs the stable REF CLK and the variable frequency sample clock and estimates a FCW frequency error and adjusts the FCW to the DDFS;
wherein the DDFS receives the FCW and outputs a digital sine codeword at the variable frequency sample clock to the DAC, wherein the FCW to the DDFS is continuously adjusted to track the variable frequency sample clock; and
wherein the DAC converts the digital sine codeword to an analog waveform.