Digital automatic gain control

Abstract

A wireless communication device (WCD) implements an improved architecture for performing automatic gain control (AGC). For example, a WCD including a wireless receiver and a modem may incorporate a digital variable gain amplifier (DVGA) and an automatic gain control (AGC) unit that have the improved architecture. In particular, the architecture of the DVGA and AGC unit may be simplified and improved specifically for handling signals modulated according to a wireless networking standard such as one of the IEEE 802.11 standards.

1 . A method comprising: 
 measuring power levels of baseband samples of an RF signal;    accumulating differences between the measured power levels and a set point;    adjusting a gain factor as a function of the accumulation; and    applying the adjusted gain factor to scale the baseband samples.    
   
   
       2 . The method of  claim 1 , further comprising accumulating the differences without translating the differences to linear values.  
   
   
       3 . The method of  claim 2 , wherein the accumulation defines a set of bits, and wherein adjusting the gain factor as a function of the accumulation comprises adjusting the gain factor according to a subset of bits of the accumulation.  
   
   
       4 . The method of  claim 3 , wherein applying the adjusted gain factor to scale the baseband samples comprises: 
 multiplying the baseband samples by the adjusted gain factor;    shifting the baseband samples to generate a shifted value; and    generating an output by selecting a subset of bits of a sum of the product and the shifted value.    
   
   
       5 . The method of  claim 1 , wherein the RF signal is modulated according to a wireless networking standard.  
   
   
       6 . A wireless communication device comprising: 
 an automatic gain control unit that measures a power level of baseband samples of an RF signal and accumulates differences between the measured power levels and a set point; and    a digital variable gain amplifier that adjusts a gain factor as a function of the accumulation and applies the adjusted gain factor to scale the baseband samples.    
   
   
       7 . The wireless communication device of  claim 6 , wherein the digital variable gain amplifier adjusts the gain factor by selecting an adjusted gain factor according to a subset of bits of the accumulation.  
   
   
       8 . The wireless communication device of  claim 7 , wherein the digital variable gain amplifier applies the adjusted gain factor by: 
 multiplying the baseband samples by the adjusted gain factor;    shifting the baseband samples to generate a shifted value; and    generating an output by selecting a subset of bits of a sum of the product and the shifted value.    
   
   
       9 . The wireless communication device of  claim 6 , wherein the RF signal is modulated according to an IEEE 802.11 standard.  
   
   
       10 . An integrated circuit comprising: 
 an automatic gain control unit that measures a power level of baseband samples of a received RF signal and accumulates measured power level errors for a number of baseband samples; and    a digital variable gain amplifier that adjusts a gain factor as a function of the accumulation and applies the adjusted gain factor to scale the baseband samples.    
   
   
       11 . The integrated circuit of  claim 10 , wherein the digital variable gain amplifier adjusts the gain factor by selecting an adjusted gain factor according to a subset of bits of the accumulation.  
   
   
       12 . The integrated circuit of  claim 11 , wherein the digital variable gain amplifier applies the adjusted gain factor by: 
 multiplying the baseband samples by the adjusted gain factor;    shifting the baseband samples to generate a shifted value; and    generating an output by selecting a subset of bits of a sum of the product and the shifted value.    
   
   
       13 . The intergrated circuit of  claim 10 , wherein the RF signal is modulated according to an IEEE 802.11 standard.  
   
   
       14 . An apparatus comprising: 
 means for measuring a power of baseband samples;    means for accumulating differences between the measurements and a set point;    means for adjusting a gain factor as a function of the accumulation; and    means for applying the adjusted gain factor to scale the baseband samples.