Programmable phase comparator
First Claim
1. A programmable phase comparator for comparing first and second substantially-periodic input signals and producing an output signal representing phase differences of the substantially-periodic input signals, the output signal having a null condition representing a first predetermined phase difference, comprising:
- switch means responsive to the first and second substantially-periodic input signals for producing the output signal representing phase differences of the first and second substantially-periodic input signals, including the null condition for the first predetermined phase difference; and
offset means connected to the switch means and responsive to a reference signal for having the null condition of the output signal instead represent a second predetermined phase difference.
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Accused Products
Abstract
A programmable phase comparator comprises a switch circuit operable in response to first and second signals to provide an output signal representative of the phase relationship of the first and second signals. A reference signal is applied to the switch circuit to offset the output signal. A phase adjustment adjusts the phase relationship of the first and second signals so that the offset output signal is representative of a null condition. The switch circuit preferably is a Gilbert multiplier having a current source, an impedance means, and a transistor circuit connected between the current source and the impedance means. The transistor circuit has first and second inputs for receiving the first and second signals. The reference signal is input between the transistor circuit and the impedance means and is connected to an output. The output provides the output signal having a value based on the reference signal and the phase relationship of the first and second signals.
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Citations
20 Claims
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1. A programmable phase comparator for comparing first and second substantially-periodic input signals and producing an output signal representing phase differences of the substantially-periodic input signals, the output signal having a null condition representing a first predetermined phase difference, comprising:
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switch means responsive to the first and second substantially-periodic input signals for producing the output signal representing phase differences of the first and second substantially-periodic input signals, including the null condition for the first predetermined phase difference; and offset means connected to the switch means and responsive to a reference signal for having the null condition of the output signal instead represent a second predetermined phase difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A programmable phase comparator comprising:
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a switch circuit having a current source, impedance means, and a transistor circuit connected between the current source and the impedance means, the transistor circuit having first and second inputs for receiving respective first and second input signals having a phase difference, the first input signal including an uninverted first signal and an inverted first signal, and the second input signal including an uninverted second signal and inverted second signal; a reference input connected between the transistor circuit and the impedance means for receiving a reference signal having a signal value selectable independently of the first and second input signals, the reference signal including an uninverted reference signal and an inverted reference signal; and an output connected to the reference input, the output providing an output signal having a component based on the signal value of the reference signal and representing the phase difference of the first and second input signals; wherein the transistor circuit comprises; a first transistor having a control terminal connected to the first input to receive the uninverted first signal, a second transistor having a control terminal connected to the first input to receive the inverted first signal, third and fourth transistors, the third transistor having a pair of terminals connected in series with the first transistor and the current source and the fourth transistor having a pair of terminals connected in series with the first transistor and the current source, the third and fourth transistors having respective control terminals coupled to the second input for respectively receiving the uninverted and inverted second signals, and fifth and sixth transistors, the fifth transistor having a pair of terminals connected in series with the second transistor and the current source and the sixth transistor having a pair of terminals connected in series with the second transistor and the current source, the fifth and sixth transistors having respective control terminals coupled to the second input for respectively receiving the inverted and uninverted second signals, the third and fifth transistors each having one terminal of its respective pair of terminals connected to the reference input to receive the uninverted reference signal and the fourth and sixth transistors each having one terminal of its respective pair of terminals connected to the reference input to receive the inverted reference signal. - View Dependent Claims (16, 17, 18, 19)
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20. A filter-tuning circuit comprising:
- an adjustable master filter for receiving a substantially-periodic input signal and outputting a substantially-periodic filtered signal based on an adjustable master cut-off frequency, an adjustable slave filter having an adjustable slave cut-off frequency, and a phase comparator for comparing the substantially-periodic input and filtered signals and outputting a phase signal for adjusting the cut-off frequencies of the master and slave filters based on a phase difference between the substantially-periodic input and filtered signals, the phase signal having a null condition representing a first predetermined phase difference, the phase comparator being characterized by
an offset circuit responsive to a reference signal for having the null condition instead represent a second predetermined phase difference, the reference signal being selectable independent of the substantially-periodic input and filtered signals.
- an adjustable master filter for receiving a substantially-periodic input signal and outputting a substantially-periodic filtered signal based on an adjustable master cut-off frequency, an adjustable slave filter having an adjustable slave cut-off frequency, and a phase comparator for comparing the substantially-periodic input and filtered signals and outputting a phase signal for adjusting the cut-off frequencies of the master and slave filters based on a phase difference between the substantially-periodic input and filtered signals, the phase signal having a null condition representing a first predetermined phase difference, the phase comparator being characterized by
Specification