Direct Radio Frequency (RF) Sampling With Recursive Filtering Method

Abstract

A radio receiver 2000 with a sampling mixer 1100 for creating a discrete-time sample stream by directly sampling an RF current with history and rotating capacitors 1111 and 1112 , wherein the accumulated charge on the rotating capacitors is read-out to produce a sample. The mixer provides immunity to noise glitches by predicting the occurrence of the glitch (or detecting a significant difference between observed and predicted samples) and creating corrected samples for the corrupted samples. These corrected samples can be created with special circuitry 1933 (digital) or in the mixer 1100 (analog).

1 . A method for glitch suppression in a discrete-time sample stream comprising:
 predicting an occurrence of a glitch;   generating a marker signal;   creating a corrected sample; and   placing the corrected sample into the discrete-time sample stream.   
   
   
       2 . The method of  claim 1 , wherein more than one corrected sample is created. 
   
   
       3 . The method of  claim 1 , wherein the corrected sample is placed into the discrete-time sample stream at a location where the occurrence of the glitch damaged a discrete-time sample. 
   
   
       4 . The method of  claim 1 , wherein the glitch is a result of a burst of digital activity. 
   
   
       5 . The method of  claim 4 , wherein clocks controlling digital circuitry are synthesized digitally and the predicting step comprises the step of detecting when a clock event will turn on a digital circuit. 
   
   
       6 . The method of  claim 1 , wherein the marker signal indicates the predicted occurrence of the glitch. 
   
   
       7 . The method of  claim 1  further comprising the step of creating a predicted sample stream prior to the predicting step, and the predicting step comprises: comparing the predicted sample stream to the discrete-time sample stream; and predicting the occurrence of a glitch if the comparison between the predicted sample stream and the discrete-time sample stream exceeds a prespecified amount. 
   
   
       8 . The method of  claim 1 , wherein the creating step comprises using a last valid sample to create the corrected sample. 
   
   
       9 . The method of  claim 8 , wherein additional valid samples are used to create the corrected sample. 
   
   
       10 . The method of  claim 9 , wherein the corrected sample is created using extrapolation of the last valid samples. 
   
   
       11 . The method of  claim 9 , wherein the corrected sample is created using statistical digital processing techniques. 
   
   
       12 . The method of  claim 8 , wherein the creating step uses valid and corrected samples to create the corrected sample. 
   
   
       13 . The method of  claim 8 , wherein the creating step uses corrected samples to create the corrected sample. 
   
   
       14 . The method of  claim 8 , wherein the using step also uses a first valid sample after the glitch to create the corrected sample. 
   
   
       15 . The method of  claim 14 , wherein additional samples are used to create the corrected sample. 
   
   
       16 . The method of  claim 14 , wherein the creating step further comprises the step of delaying the discrete-time sample stream. 
   
   
       17 . The method of  claim 16 , wherein the delay is a function of a duration of the glitch. 
   
   
       18 . The method of  claim 1 , wherein the discrete-time sample stream is created by sampling a radio frequency (RF) current with sampling capacitors, and the creating step comprises: decoupling the sampling capacitors from the RF current; and using residual information about the sampled RF current to create corrected samples. 
   
   
       19 . The method of  claim 18 , wherein the residual information is a charge on the sampling capacitors. 
   
   
       20 . The method of  claim 19 , wherein a discrete-time sample is created by reading the charge on the sampling capacitor, and the corrected samples are created by reading the charge on the sampling capacitors. 
   
   
       21 . The method of  claim 18 , wherein the decoupling step comprises stopping the sampling of the RF current. 
   
   
       22 . The method of  claim 21 , wherein the sampling of the RF current is stopped by disabling a switch windowing the RF current. 
   
   
       23 . The method of  claim 22  further comprising the step of restarting the sampling of the RF current after the placing step. 
   
   
       24 - 53 . (canceled) 
   
   
       54 . A radio receiver comprising:
 a radio frequency (RF) input to receive RF signals;   a sampling mixer coupled to the RF input to produce a discrete-time sample stream:   a timing circuit coupled to the mixer, the timing circuit to produce clock signals to control the operation of the mixer;   a clock activity detector coupled to the mixer, the clock activity detector containing circuitry to predict an occurrence of a noise glitch;   a sample predictor coupled to the clock activity detector and the mixer, the sample predictor containing circuitry to predict a value of discrete-time samples corrupted by the digital noise; and   the radio receiver further comprising a signal processing unit coupled to the mixer, the signal processing unit containing circuitry to process the output of the sampling mixer and create user usable data.   
   
   
       55 . A radio receiver comprising:
 a radio frequency (RF) input to receive RF signals;   a sampling mixer coupled to the RF input to produce a discrete-time sample stream:   a timing circuit coupled to the mixer, the timing circuit to produce clock signals to control the operation of the mixer;   a clock activity detector coupled to the mixer, the clock activity detector containing circuitry to predict an occurrence of a noise glitch;   a sample predictor coupled to the clock activity detector and the mixer, the sample predictor containing circuitry to predict a value of discrete-time samples corrupted by the digital noise;   a delay unit coupled to the mixer, the delay unit containing circuitry to insert a delay of a duration at least equal to a duration of the digital noise into the discrete-time sample stream;   a multiplexer coupled to the delay unit, the sample predictor, and the clock activity detector, the multiplexer to selects between the outputs of the sample predictor and the delay unit; and   the radio receiver further comprising a signal processing unit coupled to the mixer, the signal processing unit containing circuitry to process the output of the sampling mixer and create user usable data.