Polar analog-to-digital converter and down converter for bandpass signals

Abstract

Methods and systems for generating a digital representation of the amplitude and phase of a bandpass signal are disclosed. The methods comprise filtering the bandpass signal with a bandpass filter, generating the real and imaginary parts of the complex analytic signal with a quadrature hybrid, determining the amplitude of the complex analytic signal by adding an even power-law transform of the real and imaginary parts of the complex analytic signal, and determining the phase of the complex analytic signal by comparing the real and imaginary parts of the complex analytic signal to zero and comparing an even power-law transform of the real and imaginary parts of the complex analytic signal to each other. Analog to digital converters and methods of converting complex analytic signals to digital signals are also disclosed.

1 . A method of determining an amplitude and phase of a bandpass signal, comprising the steps of:
 generating real and imaginary parts of an analytic representation of said bandpass signal through a quadrature hybrid, wherein the real and imaginary parts of an analytic representation of said bandpass signal is an analytic signal;   determining an amplitude of the analytic signal by adding an even power-law transform of the real and imaginary parts of the analytic signal; and   determining a phase of the analytic signal by comparing the real and imaginary parts of the analytic signal to zero and comparing the even power-law transform of an absolute value of the real and imaginary parts of the analytic signal to each other.   
     
     
         2 . The method of  claim 1 , wherein an amplitude generator circuit extracts the signal amplitude or a power-law thereof. 
     
     
         3 . The method of  claim 2 , wherein the amplitude generator is comprised of a lowpass filter to attenuate generated harmonics and a power-law inverter. 
     
     
         4 . The method of  claim 3 , further comprising converting the amplitude of the analytic signal into binary signals with a linear quantizer. 
     
     
         5 . The method of  claim 2 , wherein the amplitude generator is comprised of a nonlinear quantizer. 
     
     
         6 . The method of  claim 1 , wherein the step of comparing an even power-law transform of the real and imaginary parts of the analytic signal to each other further comprises multiplying the even power-law transform of the real and imaginary parts of the analytic signal by multiple constant gains in their respective gain banks. 
     
     
         7 . The method of  claim 6 , further comprising comparing scaled versions of the real and imaginary parts of the analytic signal with a bank of comparators to generate a phase binary signal. 
     
     
         8 . The method of  claim 1 , where the even power-law transform of the real and imaginary parts of the analytic signal are logarithmically converted prior to their comparison to each other. 
     
     
         9 . A system adapted to output an amplitude and phase of a bandpass signal, comprising:
 a quadrature hybrid adapted to generate real and imaginary parts of an analytic representation of said bandpass signal, wherein the real and imaginary parts of an analytic representation of said bandpass signal is an analytic signal;   a power-law device adapted to determine an amplitude of the analytic signal by adding an even power-law transform of the real and imaginary parts of the analytic signal; and   a bank of comparators adapted to determine a phase of the analytic signal by comparing the real and imaginary parts of the analytic signal to zero and comparing the even power-law transform of the real and imaginary parts of the analytic signal to each other.   
     
     
         10 . The system of  claim 9 , further comprising an amplitude generator circuit adapted to extract the signal amplitude or a power-law thereof. 
     
     
         11 . The system of  claim 10 , wherein the amplitude generator is comprised of a lowpass filter to attenuate generated harmonics and a power-law inverter. 
     
     
         12 . The system of  claim 11 , further comprising a linear quantizer adapted to convert the amplitude of the analytic signal into binary signals. 
     
     
         13 . The system of  claim 10 , wherein the amplitude generator is comprised of a nonlinear quantizer. 
     
     
         14 . The system of  claim 9 , wherein comparing an even power-law transform of the real and imaginary parts of the analytic signal to each other further comprises multiplying the even power-law transform of the real and imaginary parts of the analytic signal by multiple constant gains in their respective gain banks. 
     
     
         15 . The system of  claim 14 , further comprising a bank of comparators to generate a phase binary signal. 
     
     
         16 . The system of  claim 9 , further comprising respective logarithmic amplifiers which act on an even power-law transform of the real and imaginary parts of the analytic signal prior to their comparison to each other. 
     
     
         17 . A method converting a bandpass analog signal to a digital signal, comprising the steps of:
 generating real and imaginary parts of an analytic representation of said bandpass signal with a quadrature hybrid, wherein the real and imaginary parts of an analytic representation of said bandpass signal is an analytic signal;   determining an amplitude of the analytic signal by adding an even power-law transform of the real and imaginary parts of the analytic signal;   converting the signal amplitude into a digital amplitude signal with a quantizer; and   converting a signal phase of the analytic signal into a digital phase signal by comparing the real and imaginary parts of the analytic signal to zero and comparing an even power-law transform of the real and imaginary parts of the analytic signal to each other.   
     
     
         18 . The method of  claim 17 , wherein the amplitude is lowpass filtered to attenuate generated harmonics previous to the quantizer 
     
     
         19 . The method of  claim 17 , wherein a power-law inverter transforms the amplitude prior to the quantizer.