Phase frequency detector circuit having reduced dead band
First Claim
1. A phase detector for detecting a phase difference between an incoming data signal and a fed-back clock signal, the phase detector comprising:
- an edge detector for detecting an edge of the data signal and the fed-back clock signal and producing at least one control signal;
a latch that receives the at least one control signal and latches a plurality of output signals in response to the at least one control signal, wherein the combination of the output signals is indicative of the phase difference between the data signal and the fed-back clock signal.
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Abstract
A digital phase detector that conducts pump up and pump down control signals to a charge pump, wherein each of the control signals has pulses that have a substantially 50/50 duty cycle characteristic when the two input signals, i.e., the input data signal and the feedback clock signal, are substantially in phase. This substantially 50/50 duty cycle output reduces, if not eliminates, inherent problems related to the turn-on delays of the charge pump while maintaining a locked condition. The phase detector may further include an intelligence to detect and handle other situations, such as missing data pulses.
143 Citations
15 Claims
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1. A phase detector for detecting a phase difference between an incoming data signal and a fed-back clock signal, the phase detector comprising:
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an edge detector for detecting an edge of the data signal and the fed-back clock signal and producing at least one control signal;
a latch that receives the at least one control signal and latches a plurality of output signals in response to the at least one control signal, wherein the combination of the output signals is indicative of the phase difference between the data signal and the fed-back clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of generating an output clock signal based on an input data signal, the method comprising:
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a) detecting a phase difference between the input data signal and a fed-back clock signal;
b) conducting at least two control signals representative of the phase difference to a charge pump, wherein the control comprising digital pulse signals have substantially equal duty cycles when the input data signal and the fed-back clock signal are substantially in phase;
c) generating a voltage signal in response to the at least two control signals; and
d) conducting the voltage signal to a voltage-controlled oscillator, which produces an oscillating output clock signal based on the voltage signal received. - View Dependent Claims (10, 11, 12, 14, 15)
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13. A phase lock loop for generating an output clock signal having substantially the same phase as an input data signal, the phase lock loop having a charge pump and a voltage controlled oscillator, the phase lock loop comprising:
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a digital phase detector for detecting the phase difference between the input data signal and a fed-back clock signal; and
means for conducting two control signals to the charge pump in response to detecting the phase difference, wherein the two control signals have substantially equal duty cycles when the input data signal and the fed-back clock signal are substantially in phase.
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Specification