Interference-free broadband television tuner
First Claim
1. A method for converting Radio Frequency (RF) signals to Intermediate Frequency (IF) signals using a first local oscillator signal having a first frequency and a second local oscillator signal having a second frequency, wherein a group of said RF signals having a first shape is converted to output signals having a second shape, said method comprising the steps of:
- identifying one or more pairs of said first and said second frequencies, wherein said pairs of frequencies are useable for converting said group of RF signals to a desired output signal frequency band;
selecting one of said pairs of frequencies, wherein said selected pair of frequencies is selected to avoid spurious signals that may cause interference in a conversion circuit and to generate output signals having a desired shape; and
converting said group of RF signals to said output signals using said selected pair of frequencies.
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Accused Products
Abstract
An interference free local oscillator circuit is disclosed. A first local oscillator signal is generated in a first phase locked loop. A second local oscillator signal is generated in a second phase locked loop. Third and fourth phase locked loops provide inputs to the second phase locked loop to control the second local oscillator frequency. The operating frequencies of the first and second local oscillator signals are selected so that spurious signals generated in the phase locked loops do not interfere with a received RF signal in a conversion circuit.
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Citations
34 Claims
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1. A method for converting Radio Frequency (RF) signals to Intermediate Frequency (IF) signals using a first local oscillator signal having a first frequency and a second local oscillator signal having a second frequency, wherein a group of said RF signals having a first shape is converted to output signals having a second shape, said method comprising the steps of:
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identifying one or more pairs of said first and said second frequencies, wherein said pairs of frequencies are useable for converting said group of RF signals to a desired output signal frequency band; selecting one of said pairs of frequencies, wherein said selected pair of frequencies is selected to avoid spurious signals that may cause interference in a conversion circuit and to generate output signals having a desired shape; and converting said group of RF signals to said output signals using said selected pair of frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A local oscillator circuit for a conversion circuit that converts Radio Frequency (RF) signals to Intermediate Frequency (IF) signals comprising:
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a first phase locked loop generating a first local oscillator signal having a first frequency; a second phase locked loop generating a second local oscillator signal having a second frequency; and means for selecting a pair of said first and said second frequencies to be used for converting said RF signals to said IF signals, wherein said pair of frequencies are selected so that spurious signals generated in said local oscillator circuit will not cause interference in said conversion circuit and so that two or more individual IF signals have a desired frequency relationship. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. A local oscillator circuit for a conversion circuit that converts Radio Frequency (RF) signals to Intermediate Frequency (IF) signals comprising:
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means for generating a first local oscillator signal; means for generating a second local oscillator signal; and means for selecting frequencies of said first and second local oscillator signals, wherein said selecting means selects said frequencies so that spurious signals generated in said local oscillator circuit do not interfere with a received RF signal and so that said IF signals have a desired frequency relationship. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method of providing local oscillator signals for a conversion circuit in which Radio Frequency (RF) signals having a first a first frequency relationship are converted to Intermediate Frequency (IF) signals having a second frequency relationship, said method comprising the steps of:
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generating one or more local oscillator signals, each of said local oscillator signals having a frequency; and selecting said frequency of said one or more local oscillator signals so that a channel in said RF signals appears within a selected range of frequencies in said IF signals, wherein said frequency of said one or more local oscillator signals is selected in said selecting step so that spurious signals do not interfere with said channel in said RF signal and so that said IF signals have a desired second frequency relationship. - View Dependent Claims (31, 32, 33, 34)
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Specification