Analog delay locked loop with tracking analog-digital converter
First Claim
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1. An analog DLL which buffers an external clock signal and uses the buffered clock signal as a reference clock signal, comprising:
- a delay model for modeling delay time for buffering the external clock signal;
a phase comparator for comparing an phase of the reference clock signal with an phase of an outputted signal from the delay model;
a charge pump for pumping charges in response to an outputted signal from the phase comparator;
a loop filter for generating a reference voltage which is determined by a quantity of charges inputted from the charge pump;
a voltage control delay line which delays the reference clock signal for a predetermined time, and outputs the delayed clock signal to the delay model, where the predetermined time is determined by the reference voltage; and
a tracking digital-analog converter which converts the reference voltage to a digital value, and stores the digital value for keeping the reference voltage safely, and outputs a tracking voltage which corresponds to the digital value to the loop filter.
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Abstract
An analog DLL device includes a delay model for modeling delay time for buffering the external clock signal; a phase comparator for comparing a phase of the reference clock signal with an phase of an outputted signal from the delay model; a charge pump for pumping charges; a loop filter for generating a reference voltage; a voltage control delay line and a tracking digital-analog converter which converts the reference voltage to a digital value; and stores the digital value for keeping the reference voltage safely.
53 Citations
20 Claims
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1. An analog DLL which buffers an external clock signal and uses the buffered clock signal as a reference clock signal, comprising:
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a delay model for modeling delay time for buffering the external clock signal;
a phase comparator for comparing an phase of the reference clock signal with an phase of an outputted signal from the delay model;
a charge pump for pumping charges in response to an outputted signal from the phase comparator;
a loop filter for generating a reference voltage which is determined by a quantity of charges inputted from the charge pump;
a voltage control delay line which delays the reference clock signal for a predetermined time, and outputs the delayed clock signal to the delay model, where the predetermined time is determined by the reference voltage; and
a tracking digital-analog converter which converts the reference voltage to a digital value, and stores the digital value for keeping the reference voltage safely, and outputs a tracking voltage which corresponds to the digital value to the loop filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An analog phase locked loop (PLL) which buffers an external clock signal and uses the buffered clock signal as a reference clock signal, comprising:
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a delay model for modeling delay time for buffering the external clock signal;
a phase comparator for comparing an phase of the reference clock signal with an phase of an outputted signal from the delay model;
a charge pump for pumping charges in response to an outputted signal from the phase comparator;
a loop filter for generating a reference voltage which is determined by a quantity of charges inputted from the charge pump;
a voltage control oscillator which modulates a frequency of the reference clock signal, and outputs the modulated signal to the delay model; and
a tracking digital-analog converter which converts the reference voltage to a digital value, and stores the digital value for keeping the reference voltage safely, and outputs a tracking voltage which corresponds to the digital value to the loop filter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification