Zerox-IF receiver with tracking second local oscillator and demodulator phase locked loop oscillator
First Claim
Patent Images
1. A zero-intermediate frequency receiver circuit for receiving a radio frequency signal detected by an antenna, the receiver circuit comprising:
- an amplifier for amplifying the radio frequency signal detected by the antenna and generating an amplified signal;
a first local oscillator circuit for generating a first local oscillator signal;
a first mixer coupled to the first local oscillator circuit and to the amplifier for mixing the amplified signal with the first local oscillator signal and generating a first mixed signal;
a base band filter coupled to the first mixer for filtering the first mixed signal and generating a filtered signal;
a voltage reference for providing a voltage reference signal;
a current reference for providing first and second current reference signals which are substantially equal;
a second local oscillator circuit coupled to the voltage reference and coupled to the current reference for receiving the first current reference signal, for generating a second local oscillator signal;
a second mixer coupled to the second local oscillator circuit and to the base band filter for mixing the filtered signal and generating at an output a second mixed signal;
a phase locked loop demodulator having an oscillator circuit coupled to the current reference for receiving the second current reference signal and coupled to the output of the second mixer for generating a phase locked loop oscillator signal, the phase locked loop demodulator for demodulating the second mixed signal to generate at an output a demodulated signal;
wherein a functional relationship between inputs and output of the second local oscillator circuit is substantially equal to a functional relationship between inputs and output of the oscillator circuit of the phase locked loop demodulator; and
a signal processor having at least a threshold input and a signal input, and an output, the threshold input of the signal processor coupled to the voltage reference, the signal input of the signal processor being coupled to the output of the phase locked loop demodulator, the signal processor generating at the output an output signal based on signals at the threshold input and signal input.
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Abstract
A zero-intermediate frequency receiver circuit (11) for receiving a radio frequency signal detected by an antenna (14). The receiver circuit (10) comprises a second local oscillator circuit (25) and an oscillator circuit (60) of a phase locked loop demodulator (36) which are identical and track each other so as to provide a more accurate reference for processing a demodulated signal. A current reference (39) providing a current reference signal utilized by the second local oscillator circuit (25) and the oscillator circuit (60) of the phase locked loop demodulator (36).
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Citations
20 Claims
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1. A zero-intermediate frequency receiver circuit for receiving a radio frequency signal detected by an antenna, the receiver circuit comprising:
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an amplifier for amplifying the radio frequency signal detected by the antenna and generating an amplified signal; a first local oscillator circuit for generating a first local oscillator signal; a first mixer coupled to the first local oscillator circuit and to the amplifier for mixing the amplified signal with the first local oscillator signal and generating a first mixed signal; a base band filter coupled to the first mixer for filtering the first mixed signal and generating a filtered signal; a voltage reference for providing a voltage reference signal; a current reference for providing first and second current reference signals which are substantially equal; a second local oscillator circuit coupled to the voltage reference and coupled to the current reference for receiving the first current reference signal, for generating a second local oscillator signal; a second mixer coupled to the second local oscillator circuit and to the base band filter for mixing the filtered signal and generating at an output a second mixed signal; a phase locked loop demodulator having an oscillator circuit coupled to the current reference for receiving the second current reference signal and coupled to the output of the second mixer for generating a phase locked loop oscillator signal, the phase locked loop demodulator for demodulating the second mixed signal to generate at an output a demodulated signal; wherein a functional relationship between inputs and output of the second local oscillator circuit is substantially equal to a functional relationship between inputs and output of the oscillator circuit of the phase locked loop demodulator; and a signal processor having at least a threshold input and a signal input, and an output, the threshold input of the signal processor coupled to the voltage reference, the signal input of the signal processor being coupled to the output of the phase locked loop demodulator, the signal processor generating at the output an output signal based on signals at the threshold input and signal input. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A zero-intermediate frequency receiver circuit for receiving a radio frequency signal detected by an antenna, the receiver circuit comprising:
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an amplifier for amplifying the radio frequency signal detected by the antenna and generating an amplified signal; a first local oscillator circuit for generating a first local oscillator signal; a first mixer coupled to the first local oscillator circuit and to the amplifier for mixing the amplified signal with the first local oscillator signal and generating a first mixed signal; a base band filter coupled to the first mixer for filtering the first mixed signal and generating a filtered signal; a voltage reference for providing a voltage reference signal; a current reference for providing first and second current reference signals which are substantially equal; a second local oscillator circuit coupled to the voltage reference and coupled to the current reference for receiving as input the first current reference signal, for generating as output a second local oscillator signal in accordance with an input to output functional relationship; a second mixer coupled to the second local oscillator circuit and to the base band filter for mixing the filtered signal and generating at an output a second mixed signal; a phase locked loop demodulator having an oscillator circuit coupled to the current reference for receiving the second current reference signal and coupled to the output of the second mixer for generating a phase locked loop oscillator signal in accordance with an input to output functional relationship, the phase locked loop demodulator for demodulating the second mixed signal to generate at an output a demodulated signal; wherein the input to output functional relationship of the second local oscillator circuit is substantially the same as the input to output functional relationship of the oscillator circuit of the phase locked loop demodulator; and a signal processor having at least a threshold input and a signal input, and an output, the threshold input of the signal processor coupled to the voltage reference, the signal input of the signal processor being coupled to the output of the phase locked loop demodulator, the signal processor generating at the output an output signal based on signals at the threshold input and signal input.
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Specification