Wide dynamic range amplifier system

Abstract

Amplifier systems and methods are provided that include a fixed gain amplification stage coupled to an adjustable attenuation stage further coupled to a variable gain amplification stage. A controller controls an amount of attenuation provided by the adjustable attenuation stage and an amount of gain provided by the variable gain amplification stage to maintain any of various noise, efficiency, and/or linearity requirements of the amplifier system.

What is claimed is: 
     
         1 . A broadband amplifier assembly having a signal input and a signal output, comprising:
 a fixed gain amplifier having an input and an output, the input coupled to the signal input;   an adjustable attenuator having an input and an output, the input of the adjustable attenuator being coupled to the output of the fixed gain amplifier;   a variable gain amplifier having an input coupled to the output of the adjustable attenuator and an output coupled to the signal output; and   a controller configured to maintain a linear relationship between a power level at the input of the variable gain amplifier and a power level at the signal output across a range of output power levels of the broadband amplifier assembly by adjusting an amount of attenuation provided by the adjustable attenuator to reduce power consumption of the broadband amplifier assembly across the range of output power levels of the broadband amplifier assembly.   
     
     
         2 . The amplifier assembly of  claim 1  wherein the variable gain amplifier has at least one amplify mode. 
     
     
         3 . The amplifier assembly of  claim 2  wherein the controller is configured to control the at least one amplify mode of the variable gain amplifier. 
     
     
         4 . The amplifier assembly of  claim 1  further comprising a bypass path switchably coupled in parallel to the variable gain amplifier and one or more switches configured to switchably route a signal through one of the variable gain amplifier and the bypass path. 
     
     
         5 . The amplifier assembly of  claim 2  wherein the bypass path includes a bypass attenuator. 
     
     
         6 . The amplifier assembly of  claim 3  wherein the bypass attenuator is a fixed attenuator. 
     
     
         7 . The amplifier assembly of  claim 3  wherein the bypass attenuator has an input impedance substantially matched to an output impedance of the adjustable attenuator and an output impedance substantially matched to an impedance of the signal output. 
     
     
         8 . The amplifier assembly of  claim 7  wherein the input impedance of the bypass attenuator has a value different from a value of the output impedance. 
     
     
         9 . A broadband amplifier assembly having a signal input and a signal output, comprising:
 a fixed gain amplifier having an input and an output, the input coupled to the signal input;   an adjustable attenuator having an input and an output, the input of the adjustable attenuator being coupled to the output of the fixed gain amplifier;   a variable gain amplifier having an input coupled to the output of the adjustable attenuator and an output coupled to the signal output; and   a controller configured to tune an amount of gain provided by the variable gain amplifier by adjusting a bias signal provided to the variable gain amplifier and adjust an amount of attenuation provided by the adjustable attenuator to reduce power consumption across a range of output power levels at the signal output of the broadband amplifier assembly.   
     
     
         10 . The amplifier assembly of  claim 9  further comprising a bypass path switchably coupled in parallel to the variable gain amplifier and one or more switches configured to switchably route a signal through one of the variable gain amplifier and the bypass path. 
     
     
         11 . The amplifier assembly of  claim 10  wherein the bypass path includes a bypass attenuator. 
     
     
         12 . The amplifier assembly of  claim 9  wherein the variable gain amplifier has at least one amplify mode. 
     
     
         13 . The amplifier assembly of  claim 12  wherein the controller is configured to control the at least one amplify mode of the variable gain amplifier. 
     
     
         14 . The amplifier assembly of  claim 12  wherein adjusting the bias signal further comprises reducing the bias signal to reduce the amount of gain provided by the variable gain amplifier within the at least one amplify mode. 
     
     
         15 . The amplifier assembly of  claim 12  wherein the controller is configured to adjust the bias signal within the at least one amplify mode based upon at least one of a desired signal level at the signal output, a signal level at the input of the variable gain amplifier, and the amount of attenuation provided by the adjustable attenuator. 
     
     
         16 . The amplifier assembly of  claim 9  wherein the controller is configured to adjust the bias signal based upon a lookup table. 
     
     
         17 . A method for reducing power consumption in a broadband amplifier assembly, the method comprising:
 receiving an input signal having an input signal level at the signal input;   selecting one of a plurality of amplify modes for a variable gain amplifier, the selected amplify mode being selected based on the input signal level and a desired output signal level at the signal output;   amplifying the input signal by a fixed amount to provide an amplified input signal;   adjusting an amount of attenuation provided by an adjustable attenuator based on the selected amplify mode of the variable gain amplifier and the desired output signal level to provide an attenuator output signal; and   reducing a level of a bias signal provided to the variable gain amplifier within the selected amplify mode to provide an output signal at the desired output signal level.   
     
     
         18 . The method of  claim 17  wherein reducing the level of the bias signal provided to the variable gain amplifier reduces an amount of gain provided by the variable gain amplifier. 
     
     
         19 . The method of  claim 17  further comprising switchably routing the attenuator output signal through the variable gain amplifier instead of a bypass path that bypasses the variable gain amplifier to provide the output signal at the desired output signal level. 
     
     
         20 . The method of  claim 19  wherein reducing the level of the bias signal provided to the variable gain amplifier includes reducing the bias signal within the selected amplify mode based upon the desired signal level at the signal output, a signal level of the attenuator output signal, and an amount of gain provided by the selected amplifier mode.