Digital voltage gain amplifier for zero if architecture

Abstract

The invention is directed toward a digital VGA that is implemented in the logarithmic domain. The digital VGA exploits logarithmic properties to replace a complex multiplier of a conventional digital VGA with a simple and inexpensive adder. Moreover, additional techniques are described to significantly reduce the size of one or more lookup tables (LUTs) implemented within the digital VGA. In this manner, the invention can realize a simple, low cost digital VGA.

1 . A method comprising: 
 converting a first digital signal from a linear domain to a logarithmic domain,    adding the converted digital signal and a second digital signal to generate a scaled digital signal; and    converting the scaled digital signal from the logarithmic domain to the linear domain.    
     
     
         2 . The method of  claim 1 , wherein the first digital signal is a baseband signal and the second digital signal is a gain value.  
     
     
         3 . The method of  claim 1 , wherein the first digital signal is a first baseband signal and the second digital signal is a second baseband signal, the method further comprising converting the second digital signal from a linear domain to a logarithmic domain prior to adding the converted digital signal and the second digital signal.  
     
     
         4 . The method of  claim 1 , further comprising processing the scaled digital signal in the linear domain.  
     
     
         5 . The method of  claim 1 , further comprising converting the first digital signal from the linear domain to the logarithmic domain by accessing a lookup table.  
     
     
         6 . The method of  claim 1 , further comprising converting the scaled digital signal from the logarithmic domain to the linear domain by accessing a lookup table.  
     
     
         7 . The method of  claim 1 , further comprising saturating the scaled digital signal prior to converting the scaled digital signal from the logarithmic domain to the linear domain.  
     
     
         8 . The method of  claim 1 , further comprising truncating the scaled digital signal prior to converting the scaled digital signal from the logarithmic domain to the linear domain.  
     
     
         9 . The method of  claim 2 , wherein the scaled digital signal is an attenuated signal having a value less than the baseband signal.  
     
     
         10 . The method of  claim 2 , wherein the scaled digital signal is an amplified signal having a value greater than the baseband signal.  
     
     
         11 . A method comprising: 
 converting a baseband signal from a linear domain to a logarithmic domain;    adding the converted baseband signal to a gain to generate a scaled baseband signal;    saturating the scaled baseband signal;    converting the saturated baseband signal from the logarithmic domain to the linear domain; and    processing the saturated baseband signal in the linear domain.