Sampling Threshold Detector for Direct Monitoring of RF Signals

1. A sampling threshold detector for monitoring a band to detect when a threshold is exceeded by a radio frequency (RF) signal, the sampling threshold detector comprising: a clocked sampler configured to sample the RF signal at a sampling clock frequency (f SAMP ) based on a local oscillator frequency (f LO ) and to position kickback intermodulation products that are produced by operation of the sampler such that when the RF signal is mixed down to the baseband intermediate frequency (f IF ) the intermodulation products are out-of-band; a passive attenuator configured to receive the RF signal, the passive attenuator allowing the detector to monitor higher voltages to provide a reverse path attenuation of noise generated by the clocked sampler; and a continuous time pre-amplifier configured to receive the output of the passive attenuator and to subtract a static programmable threshold voltage therefrom and to provide the resulting signal to the clocked sampler as the RF signal to be sampled.

2. The sampling threshold detector of claim 1 wherein the clocked sampler is a single high bandwidth sampler.

3. The sampling threshold detector of claim 1 wherein the sampling clock frequency (f SAMP ) is determined based on the local oscillator frequency (f LO ) and the baseband intermediate frequency (f IF ).

4. The sampling threshold detector of claim 3 wherein the sampling clock frequency f SAMP is determined according to f SAMP =f LO +N*f IF , where N is an integer that results in a positive sampling frequency within an acceptable operating range of the clocked sampler.

5. The sampling threshold detector of claim 1 further comprising a machine readable memory storing a set of candidate sampling clock frequency values from which the sampling clock frequency for the clocked sampler is selected.

6. The sampling threshold detector of claim 1 further comprising: a filter provided before the continuous time pre-amplifier and configured to capture the peak of the RF signal within a particular frequency band.

7. The sampling threshold detector of claim 1 wherein the sampler comprises a single high bandwidth clocked sampler directly attached to the RF signal, enabling direct monitoring of the RF signal.

8. The sampling threshold detector of claim 1 wherein the clocked sampler provides a digitized output having a digital output value, the digital output value being based on whether or not the RF signal exceeds the threshold.

9. A method of sampling threshold detection comprising: monitoring a radio frequency (RF) signal using a single high bandwidth clocked sampler; selecting a sampling clock frequency (f SAMP ) based on a local oscillator frequency; operating the single high bandwidth clocked sampler at the selected sampling clock frequency (f SAMP ) to position kickback intermodulation products that are produced by operation of the clocked sampler such that when the RF signal is mixed down to the baseband intermediate frequency (f IF ) the intermodulation products are out-of-band; and receiving the RF signal to monitor higher voltages to provide a reverse path attenuation of noise generated by the single high bandwidth clocked sampler; and subtracting a static programmable threshold voltage to provide the resulting signal to the single high bandwidth clocked sampler as the RF signal to be sampled.

10. The method of claim 9 further comprising: pre-calculating intermodulation products for each signal to be received; and selecting the sampling clock frequency additionally based on the pre-calculated intermodulation products.

11. The method of claim 9 further comprising: calculating at run-time intermodulation products for each signal to be received; and selecting the sampling clock frequency additionally based on the intermodulation products calculated at run-time.

12. The method of claim 9 wherein the final folded results of the kickback intermodulation products are positioned out of band, or are of low enough power in-band so as to be inconsequential.

13. The method of claim 9 wherein the sampling clock frequency (f SAMP ) is determined based on the local oscillator frequency (f LO ) and the baseband intermediate frequency (f IF ).

14. The method of claim 13 wherein the sampling clock frequency f SAMP is determined according to f SAMP =f LO +N*f IF , where N is an integer that results in a positive sampling frequency within an acceptable operating range of the single high bandwidth clocked sampler.

15. The method of claim 9 further comprising storing a set of candidate sampling clock frequency values from which the sampling clock frequency for the single high bandwidth clocked sampler is selected.

16. The method of claim 9 further comprising: capturing the peak of the RF signal within a particular frequency band.

17. The method of claim 9 further comprising directly monitoring the RF signal by sampling the RF signal using the single high bandwidth clocked sampler directly attached to the RF signal.

18. The method of claim 9 wherein the single high bandwidth clocked sampler provides a digitized output having a digital output value, the digital output value being based on whether or not the RF signal exceeds the threshold.