Synchronous carrier recovery circuit and injection locked oscillator
First Claim
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1. An injection locked oscillator comprising:
- an inverter stage;
a crystal connected across said inverter stage to establish a nominal oscillation of said injection locked oscillator; and
an injection transistor connected to said inverter stage to control a gain of said inverter stage in accordance with an externally input modulated signal.
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Abstract
A simple carrier recovery circuit capable of accurately detecting and synchronizing an incoming carrier frequency without the use of a phase locked loop (PLL) is provided. Instead of a PLL, the carrier recovery circuit includes an injection locked oscillator. The injection locked oscillator includes an input for connection to the received modulated signal. The gain of an inverter stage of a amplifier in the injection locked oscillator is modulated by the received modulated signal using an injection transistor connected between the power source and the output of the inverter stage. The gate of the injection transistor receives a signal corresponding to the received modulated signal.
22 Citations
21 Claims
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1. An injection locked oscillator comprising:
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an inverter stage; a crystal connected across said inverter stage to establish a nominal oscillation of said injection locked oscillator; and an injection transistor connected to said inverter stage to control a gain of said inverter stage in accordance with an externally input modulated signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A synchronous carrier recovery circuit comprising:
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a phase/frequency detector having a first input, a second input, and an output, said phase/frequency detector comprising a comparator to compare a frequency and phase of a first signal on said first input to a frequency and phase of a second signal on said second input, and to output a difference between said first signal and said second signal on said output; and an injection locked oscillator in communication with an injection signal corresponding to said second signal, said injection locked oscillator including an oscillator to oscillate at a detected carrier frequency, said injection locked oscillator allowing said injection signal to modulate a characteristic of said oscillator. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of injecting a modulated signal into a circuit, said method comprising:
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providing a crystal oscillator; and modulating a gain of said crystal oscillator based on said injected modulated signal. - View Dependent Claims (16)
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17. An injection locked oscillator comprising:
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oscillator means; crystal means in parallel with said oscillator means; and gain control means for controlling a gain of said oscillator means in accordance with a modulated input signal. - View Dependent Claims (18, 19, 20, 21)
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Specification