Digitally controlled oscillator with thermometer sigma delta encoded frequency control word
First Claim
1. An all digital phase locked loop (ADPLL) for generating an output clock signal from a reference clock signal, the ADPLL comprising:
- a thermometer pulse coder including a plurality of frequency control word signal lines, where the thermometer pulse coder is configured to;
generate a frequency control word from a binary encoded frequency control word, where the frequency control word includes a plurality of thermometer coded signals and a pulse modulated dither signal; and
select one of the plurality of frequency control word signal lines and transmit the pulse modulated dither signal over the selected frequency control word signal line and transmit the thermometer coded signals over a plurality of the other frequency control word signal lines;
a digitally controlled oscillator configured to receive a frequency control word comprising a combined thermometer and pulse modulated signal via the plurality of frequency control world signal lines and generate an output clock signal at a frequency determined using at least the frequency control word;
a feedback divider configured to receive the output clock signal from the digitally controlled oscillator and generate a feedback signal; and
a phase detector configured to receive a reference clock signal and a feedback signal from the feedback divider and generate a phase error signal, which is provided to a digital loop filter configured to generate a binary encoded frequency control word that is input to the thermometer pulse coder.
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Abstract
Systems and methods for generating a thermometer sigma delta encoded frequency control word for controlling a digitally controlled oscillator in accordance with embodiments of the invention are disclosed. In one embodiment, an all digital phase locked loop for generating an output clock signal includes a thermometer pulse coder configured to generate a frequency control word (FCW) that includes thermometer coded signals and a pulse modulated dither signal, and transmit the pulse modulated dither signal over a selected FCW signal line and transmit the thermometer coded signals over other FCW signal lines, and a digitally controlled oscillator to receive a FCW comprising a combined thermometer and pulse modulated signal and generate an output clock signal.
25 Citations
17 Claims
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1. An all digital phase locked loop (ADPLL) for generating an output clock signal from a reference clock signal, the ADPLL comprising:
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a thermometer pulse coder including a plurality of frequency control word signal lines, where the thermometer pulse coder is configured to; generate a frequency control word from a binary encoded frequency control word, where the frequency control word includes a plurality of thermometer coded signals and a pulse modulated dither signal; and select one of the plurality of frequency control word signal lines and transmit the pulse modulated dither signal over the selected frequency control word signal line and transmit the thermometer coded signals over a plurality of the other frequency control word signal lines; a digitally controlled oscillator configured to receive a frequency control word comprising a combined thermometer and pulse modulated signal via the plurality of frequency control world signal lines and generate an output clock signal at a frequency determined using at least the frequency control word; a feedback divider configured to receive the output clock signal from the digitally controlled oscillator and generate a feedback signal; and a phase detector configured to receive a reference clock signal and a feedback signal from the feedback divider and generate a phase error signal, which is provided to a digital loop filter configured to generate a binary encoded frequency control word that is input to the thermometer pulse coder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification