Demodulator and method for second harmonic cancellation
First Claim
1. A demodulator circuit;
- comprising;
an oscillator having a first input coupled for receiving a signal;
a phase shift circuit having an input coupled to an output of the oscillator;
a first multiplier having a first input coupled for receiving the signal and a second input coupled to the output of the oscillator;
a second multiplier having a first input coupled to an output of the phase shift circuit and a second input coupled to the output of the oscillator; and
a summing circuit having a first input coupled to an output of the first multiplier, a second input coupled to an output of the second multiplier and an output.
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Accused Products
Abstract
A demodulator circuit (10) having harmonic cancelling receives an input signal (IF) and generates an oscillator signal (OSC) in an oscillator circuit (14). The oscillator signal (OSC) is locked to the same frequency and phase as the input signal (IF). A phase shift circuit (18) generates a shifted signal (OSC SHIFTED) that is in quadrature with the oscillator signal (OSC). A multiplier (22) receives the oscillator signal (OSC) and the shifted signal (OSC SHIFTED) and generates an output signal (2IF) having twice the frequency of the oscillator signal (OSC). A multiplier circuit (24) also receives the input signal (IF) and along with the oscillator signal (OSC) generates an output signal (PD). The signals generated by the multiplier (22) and the multiplier circuit (24) are summed in a summing circuit (30) that supplies an output signal (OUT).
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Citations
12 Claims
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1. A demodulator circuit;
- comprising;
an oscillator having a first input coupled for receiving a signal;
a phase shift circuit having an input coupled to an output of the oscillator;
a first multiplier having a first input coupled for receiving the signal and a second input coupled to the output of the oscillator;
a second multiplier having a first input coupled to an output of the phase shift circuit and a second input coupled to the output of the oscillator; and
a summing circuit having a first input coupled to an output of the first multiplier, a second input coupled to an output of the second multiplier and an output. - View Dependent Claims (2, 3, 4)
- comprising;
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5. A circuit, comprising:
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an oscillator circuit having a first input for receiving a signal, a second input for receiving a frequency control signal;
a first multiplier having a first input coupled for receiving the signal and a second input coupled for receiving an oscillator signal from the oscillator; and
a second multiplier having a first input coupled for receiving the oscillator signal from the oscillator and a second input coupled for receiving a phase shifted oscillator signal that is in quadrature to the oscillator signal. - View Dependent Claims (6, 7)
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8. A method for cancelling a second harmonic of an input signal, comprising:
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generating an oscillator signal that is locked to the input signal and a phase shifted oscillator signal;
multiplying the oscillator signal and the phase shifted oscillator signal to generate a first multiplied signal;
multiplying the input signal and the oscillator signal to generate a second multiplied signal;
summing the first multiplied signal and the second multiplied signal to generate an output signal having the second harmonic cancelled. - View Dependent Claims (9, 10, 11, 12)
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Specification