Nyquist folded bandpass sampling receivers with narrow band filters for UWB pulses and related methods
View Patent ↗Nyquist folded bandpass sampling receivers are disclosed that utilize narrow band filters in parallel with wideband filters to enhance reception of ultra wideband (UWB) pulses. The addition of the narrow band filter facilitates the reception of ultra wideband signal pulses and, therefore, extends the Nyquist folding bandpass sampling receiver to allow improved processing of ultra wideband (UWB) pulses. RF sampling circuitry utilizing a modulated sampling clock signal can then better capture UWB pulse signals.
1. Receive path circuitry for a bandpass sampling receiver having folded Nyquist zones and ultra wideband pulse capabilities, comprising:
wideband filter circuitry receiving an RF input signal, having a center frequency within a frequency range of interest and having a bandwidth less than or equal to the frequency range of interest and wide enough to cover multiple Nyquist zones associated with a modulated sampling clock;
narrow band filter circuitry receiving the RF input signal and having a center frequency within a frequency range of interest and having a bandwidth less than the Nyquist bandwidth of the modulated sampling clock; and
sampling circuitry configured to receive a filtered signal from the wideband filter circuitry, to receive a filtered signal from the narrow band filter circuitry, and to receive the modulated sampling clock signal as an input, the modulated sampling clock signal being configured to provide non-uniform sampling for signals within the multiple Nyquist zones.
2. The receive path circuitry of claim 1 , wherein the modulated sampling clock signal comprises a frequency modulated clock signal.
3. The receive path circuitry of claim 2 , wherein the frequency modulated clock signal comprises a linear sawtooth modulation, a sinusoidal modulation, a triangle modulation, a frequency shift key modulation, a frequency agile modulation, a communications frequency modulation, or a combination thereof.
4. The receive path circuitry of claim 2 , wherein the sampling circuitry comprises:
non-quantizing sampling circuitry;
an analog interpolation filter coupled to receive the output of the non-quantizing sampling circuitry, the analog interpolation filter having a center frequency within a Nyquist zone of operation for the non-quantizing sampling circuitry; and
analog to digital converter (ADC) circuitry configured to receive a quantization sampling clock signal and to quantize an analog signal received from the analog interpolation filter.
5. The receive path circuitry of claim 4 , wherein the analog interpolation filter comprises a tunable or switchable interpolation filter.
6. The receiver path circuitry of claim 1 , wherein the modulated sampling clock comprises a frequency modulated sampling clock having a tunable frequency or an adjustable modulation or both.
7. The receive path circuitry of claim 1 , wherein the wideband filter circuitry comprises a wideband filter having bandwidth of 10 GHz or more, the modulated sampling clock has a sampling rate of 1 GHz or more, and the narrow band filter circuitry comprises a bandwidth less than 1 GHz.
8. The receive path circuitry of claim 1 , wherein the wideband filter circuitry comprises a wideband filter having bandwidth of 20 GHz or more, the modulated sampling clock has a sampling rate of 2 GHz or more, and the narrow band filter circuitry comprises a bandwidth less than 2 GHz.
9. The receive path circuitry of claim 1 , wherein the wideband filter circuitry comprises a tunable bandpass filter having a tunable center frequency dependent upon a filter control signal, the center frequency being tunable across the frequency range of interest, and the tunable bandpass filter having a bandwidth less than the frequency range of interest.
10. The receive path circuitry of claim 1 , wherein the narrow band filter circuitry comprises one or more tunable narrow band filters each having a tunable center frequency dependent upon a filter control signal and each being tunable across the frequency range of interest.
11. The receive path circuitry of claim 1 , further comprising digital signal processing circuitry coupled to receive an output from the sampling circuitry and configured to identify ultra wideband pulses based upon signals passed through the narrow band filter circuitry.
12. A method for bandpass sampling of signals using folded Nyquist zones, comprising:
utilizing wideband filter circuitry to filter an RF input signal within a frequency range of interest, the bandpass filter having a bandwidth less than or equal to the frequency range of interest and wide enough to cover multiple Nyquist zones associated with a modulated sampling clock;
also filtering the RF input signal with narrow band filter circuitry having a center frequency within a frequency range of interest and having a bandwidth less than the Nyquist bandwidth of the modulated sampling clock;
combining an output signal from the wideband filter circuitry with an output signal from the narrow band filter circuitry to generate a combined filtered signal;
generating a modulated sampling clock configured to provide non-uniform sampling for signals within the multiple Nyquist zones; and
bandpass sampling the combined filtered signal from the wideband filter circuitry covering multiple Nyquist zones using the modulated sampling clock.
13. The method of claim 12 , wherein the generating step comprises generating a chirp frequency modulated clock signal for the modulated sampling clock signal.
14. The method of claim 12 , wherein the bandpass sampling step comprises:
bandpass sampling the combined filtered signal without quantizing the signal;
filtering the sampled signal with an analog interpolation filter having a center frequency within a Nyquist zone; and
quantizing a signal received from the analog interpolation filter.
15. The method of claim 14 , wherein the generating step comprises generating a frequency modulated clock signal for the modulated sampling clock signal.
16. The method of claim 14 , further comprising using a tunable or switchable interpolation filter as the analog interpolation filter.
17. The method of claim 12 , wherein the utilizing step comprises utilizing wideband filter circuitry having a bandwidth of 10 GHz or more, wherein the generating step comprises generating a modulated sampling clock signal having a sampling rate of 1 GHz or more, and wherein the filtering step comprises filtering with narrow band filter circuitry having a bandwidth less than 1 GHz.
18. The method of claim 12 , wherein the utilizing step comprises utilizing wideband filter circuitry having a bandwidth of 20 GHz or more, wherein the generating step comprises generating a modulated sampling clock signal having a sampling rate of 2 GHz or more, and wherein the filtering step comprises filtering with narrow band filter circuitry having a bandwidth less than 2 GHz.
19. The, method of claim 12 , wherein the utilizing step comprises utilizing one or more tunable bandpass filters and further comprising tuning the center frequency of the tunable bandpass filter within the frequency range of interest.
20. The method of claim 12 , wherein the filtering step comprises filtering the RF input signal with one or more tunable narrow band filters and further comprising tuning the center frequency of the one or more tunable narrow band filters within the frequency range of interest.
21. The method of claim 12 , further comprising processing sampled signals to identify ultra wideband pulses based upon signals passed through the narrow band filter circuitry.