Simplified high frequency tuner and tuning method
First Claim
1. A tuning device comprising:
- (a) input circuitry that receives an RF signal containing a channel of interest from a channelized spectrum;
(b) mixers and local oscillator signal generators configurable to produce I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having a frequency that is one of a set of local oscillator frequencies determined by the channel spacing; and
(c) filter circuitry configurable to filter the I and Q signals to define a near-baseband passband determined by the bandwidth of the signal of interest and whose lower edge is situated near baseband but spaced from DC by at least about the channel spacing.
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Abstract
A disdosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.
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Citations
19 Claims
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1. A tuning device comprising:
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(a) input circuitry that receives an RF signal containing a channel of interest from a channelized spectrum; (b) mixers and local oscillator signal generators configurable to produce I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having a frequency that is one of a set of local oscillator frequencies determined by the channel spacing; and (c) filter circuitry configurable to filter the I and Q signals to define a near-baseband passband determined by the bandwidth of the signal of interest and whose lower edge is situated near baseband but spaced from DC by at least about the channel spacing. - 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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Specification