Automatic selection of an operating frequency in a low-gain broadband phase lock loop system
First Claim
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1. A phase-lock loop system for automatically frequency-locking a signal in phase with a reference signal, said system comprising:
- a. a reference source for providing a reference signal;
b. a phase and frequency detector for comparing said reference signal to said signal, said phase and frequency detector coupled to said reference source;
c. an up/down counter coupled to said phase and frequency detector;
d. a digital-to-analog converter for providing an analog control signal, said digital-to-analog converter coupled to said up/down counter;
e. a decoder for providing a digital control signal, said decoder coupled to said up/down counter; and
f. a ring oscillator having a plurality of stages connected in tandem, said ring oscillator coupled to said digital-to-analog converter and to said decoder, said ring oscillator having a digital input for receiving said digital control signal and an analog input for receiving said analog control signal, wherein each of said plurality of stages of said ring oscillator includes an anti-high gain circuit.
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Abstract
A broadband low-gain system for automatically frequency-locking a signal where the system uses digital and analog devices and techniques. The system includes a comparator, an up/down counter, a digital-to-analog converter, a decoder, a ring oscillator and a downcounter. The digital control signal is provided by the decoder and actuates one of a plurality of ring oscillator stages. The analog control signal is provided by the digital-to analog-converter and controls a fine-tune mechanism in the actuated stage. The system includes a master reset for clearing the counters.
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Citations
13 Claims
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1. A phase-lock loop system for automatically frequency-locking a signal in phase with a reference signal, said system comprising:
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a. a reference source for providing a reference signal; b. a phase and frequency detector for comparing said reference signal to said signal, said phase and frequency detector coupled to said reference source; c. an up/down counter coupled to said phase and frequency detector; d. a digital-to-analog converter for providing an analog control signal, said digital-to-analog converter coupled to said up/down counter; e. a decoder for providing a digital control signal, said decoder coupled to said up/down counter; and f. a ring oscillator having a plurality of stages connected in tandem, said ring oscillator coupled to said digital-to-analog converter and to said decoder, said ring oscillator having a digital input for receiving said digital control signal and an analog input for receiving said analog control signal, wherein each of said plurality of stages of said ring oscillator includes an anti-high gain circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of automatically frequency-locking a signal in phase with a reference signal, said method comprising the steps of:
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a. comparing a reference signal with said signal; b. generating up and down commands; c. providing, in response to said up and down commands, a first digital control signal and a second digital control signal; d. converting said first digital control signal to an analog signal; e. decoding said second digital control signal to a decoded digital control signal; f. actuating a single stage in a multi-stage ring oscillator by applying said decoded digital control signal to a digital input of said multi-stage ring oscillator; g. providing to each stage of said multi-stage ring oscillator means for regulating high gain of said stage; and h. fine controlling said multi-stage ring oscillator by applying said analog signal to an analog input of said multi-stage ring oscillator. - View Dependent Claims (12, 13)
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Specification