Bandpass sampling architecture for wide-frequency band signal analysis
First Claim
1. A method of sampling an electrical input signal spectrum having a wide frequency band comprising:
- receiving an input signal having a base range of frequency components within the wide frequency band;
converting the base range of frequency components to an intermediate range of frequency components above the base range of frequency components;
bandpass filtering the intermediate range of frequency components to generate a relatively narrow bandpass range of frequency components; and
sampling and digitizing the relatively narrow bandpass range of frequency components.
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Abstract
A bandpass sampling system (10) of this invention employs a conventional mixer (14) driven by a frequency-tunable LO (16) to upconvert a signal frequency band to an IF frequency band that is above the signal frequency band. The IF frequency band is passed through an IF bandpass filter (18) to provide to subsequent digitization stages (20, 24) an IF bandpass range of signal frequency components. In this architecture, the IF bandpass filter acts as an anti-alias filter for the digitization stages. The LO frequency is selected to place the upconverted signal frequency band within the pass band of the IF bandpass filter. The resultant IF bandpass signal is sampled and digitized at a rate that is commensurate with the IF bandwidth, but typically much lower than the IF bandpass center frequency. Signal sampling is carried out by a sample-and-hold or a track-and-hold circuit (20), the output of which is applied to an ADC (24) that is clocked (22) at the same rate as the sampling circuit.
48 Citations
22 Claims
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1. A method of sampling an electrical input signal spectrum having a wide frequency band comprising:
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receiving an input signal having a base range of frequency components within the wide frequency band;
converting the base range of frequency components to an intermediate range of frequency components above the base range of frequency components;
bandpass filtering the intermediate range of frequency components to generate a relatively narrow bandpass range of frequency components; and
sampling and digitizing the relatively narrow bandpass range of frequency components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22)
sampling the relatively narrow bandwidth range of frequency components to produce data samples; and
digitizing the data samples.
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22. The method as recited in claims 1 or 21 wherein the sampling and digitizing step is carried out at a frequency that is greater than about twice the bandwidth of the relatively narrow bandwidth range of frequency components.
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11. An apparatus for sampling an electrical input signal spectrum having a wide frequency band comprising:
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a mixer receiving an input signal having a base range of frequency components within the wide frequency band and converting the base range of frequency components to an intermediate range of frequency components above the base range of frequency components;
a bandpass filter filtering the intermediate range of frequency components to generate a relatively narrow bandpass range of frequency components;
a sampling circuit performing one of a sample-and-hold and a track-and-hold operation on the relatively narrow bandpass range of frequency components to provide data samples; and
an analog-to-digital converter digitizing the data samples. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification