Low-cost receiver using tracking bandpass filter and lowpass filter
First Claim
1. A receiver, comprising:
- a tracking bandpass filter having an input for receiving an RF input signal, and an output;
a tunable lowpass filter having an input coupled to said output of said tracking bandpass filter, and an output;
a local oscillator having a first output for providing a local oscillator signal at a frequency chosen to mix a selected channel to a desired intermediate frequency, said local oscillator signal characterized as being a square wave signal at said desired intermediate frequency; and
a mixer having a first input coupled to said output of said tunable lowpass filter, a second input coupled to said first output of said local oscillator, and a first output for providing an intermediate frequency (IF) signal at said desired intermediate frequency,wherein said tunable lowpass filter is configured to substantially attenuate said output of said tracking bandpass filter above a third harmonic of said frequency of said local oscillator signal.
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Accused Products
Abstract
A receiver (400) includes a tracking bandpass filter (420), a tunable lowpass filter (434), a local oscillator (442), and a mixer (444). The tracking bandpass filter (420) has an input for receiving a radio frequency (RF) input signal, and an output. The tunable lowpass filter (434) has an input coupled to the output of the tracking bandpass filter (420), and an output. The local oscillator (422) has a first output for providing a local oscillator signal, which is characterized as being a square wave signal at the desired intermediate frequency (IF). The mixer (444) has a first input coupled to the output of the tunable lowpass filter (434), a second input coupled to the output of the local oscillator (442), and a first output for providing an IF signal at the desired IF. The tunable lowpass filter (434) is configured to substantially attenuate a third harmonic of the frequency of the local oscillator signal.
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Citations
23 Claims
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1. A receiver, comprising:
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a tracking bandpass filter having an input for receiving an RF input signal, and an output; a tunable lowpass filter having an input coupled to said output of said tracking bandpass filter, and an output; a local oscillator having a first output for providing a local oscillator signal at a frequency chosen to mix a selected channel to a desired intermediate frequency, said local oscillator signal characterized as being a square wave signal at said desired intermediate frequency; and a mixer having a first input coupled to said output of said tunable lowpass filter, a second input coupled to said first output of said local oscillator, and a first output for providing an intermediate frequency (IF) signal at said desired intermediate frequency, wherein said tunable lowpass filter is configured to substantially attenuate said output of said tracking bandpass filter above a third harmonic of said frequency of said local oscillator signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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selectively bandpass filtering a radio frequency (RF) input signal based on a tuning signal to provide a partially filtered RF signal; generating a first square wave local oscillator signal at a frequency chosen to mix a selected channel to a desired intermediate frequency (IF); lowpass filtering said partially filtered RF signal using a cutoff frequency to provide a fully filtered RF signal, said cutoff frequency selected to substantially attenuate said partially filtered RF signal above a third harmonic of said first square wave local oscillator signal; and mixing said fully filtered RF signal using said first square wave local oscillator signal to provide a first IF signal at said predetermined IF. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A receiver, comprising:
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a tracking bandpass filter for bandpass filtering a selected channel of a radio frequency (RF) signal to provide a partially filtered output; a tunable lowpass filter for lowpass filtering said partially filtered output to provide a fully filtered output; and a mixer for mixing said fully filtered output with a square wave local oscillator signal having a frequency chosen to mix said selected channel to a desired intermediate frequency (F); wherein said tunable lowpass filter is configured to substantially attenuate said partially filtered output above a third harmonic of said frequency of said square wave local oscillator signal. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification