Method and apparatus for changing the gain of a radio frequency signal

Abstract

A method and electronic circuit for changing the gain of a radio frequency signal. The apparatus is an electronic circuit comprising one or more variable gain electronic elements, and one or more adjustable phase shifting elements. The method comprises the steps of receiving a radio frequency signal, varying the gain of the variable gain electronic element while the variable gain electronic element changes the amplitude of the radio frequency signal, and adjusting an adjustable phase shifting element to generate a reverse phase shift in the radio frequency signal in response to the associated phase shift from the step of varying the gain.

1 - 13 . (canceled) 
     
     
         14 . A system comprising:
 a variable gain amplifier (VGA) that introduces an unwanted phase shift when an amplification of an analog radio frequency (RF) signal is changed; and   a phase shifter operable to offset the unwanted phase shift according to an adjustment of a capacitance, wherein the capacitance of the phase shifter is initially set to a predetermined level.   
     
     
         15 . The system of  claim 14 , wherein the offset of the unwanted phase shift is sufficient to reduce bit errors in the amplified RF signal. 
     
     
         16 . The system of  claim 14 , wherein the capacitance of the phase shifter is controlled by a varactor. 
     
     
         17 . The system of  claim 14 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a linearly weighted configuration. 
     
     
         18 . The system of  claim 14 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a binary weighted configuration. 
     
     
         19 . The system of  claim 14 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a cascade configuration. 
     
     
         20 . The system of  claim 14 , wherein the VGA comprises a voltage gain amplifier. 
     
     
         21 . The system of  claim 14 , wherein the VGA comprises a plurality of switched resistors. 
     
     
         22 . The system of  claim 14 , wherein the VGA comprises an adjustable resistive divider. 
     
     
         23 . The system of  claim 14 , wherein the capacitance of the phase shifter is controlled digitally. 
     
     
         24 . A method comprising:
 changing the amplification of an analog radio frequency (RF) signal with a variable gain amplifier (VGA) that introduces an unwanted phase shift; and   controlling a capacitance of a phase shifter to offset the unwanted phase shift, wherein the capacitance of the phase shifter is initially set to a predetermined level.   
     
     
         25 . The method of  claim 24 , wherein the offset of the unwanted phase shift is sufficient to reduce bit errors in the amplified RF signal. 
     
     
         26 . The method of  claim 24 , wherein the capacitance of the phase shifter is controlled by a varactor. 
     
     
         27 . The method of  claim 24 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a linearly weighted configuration. 
     
     
         28 . The method of  claim 24 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a binary weighted configuration. 
     
     
         29 . The method of claim  42 , wherein the capacitance of the phase shifter is controlled by a plurality of parallel switched capacitors arranged in a cascade configuration. 
     
     
         30 . The method of  claim 24 , wherein the VGA comprises a voltage gain amplifier. 
     
     
         31 . The method of  claim 24 , wherein the VGA comprises a plurality of switched resistors. 
     
     
         32 . The method of  claim 24 , wherein the VGA comprises an adjustable resistive divider. 
     
     
         33 . The method of  claim 24 , wherein the capacitance of the phase shifter is controlled digitally.