Methods of adjusting band-based amplifier linearity

Abstract

A method to improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing is operating channel dependent. A bias current for an amplifying transistor of an amplifier circuit is determined based at least in part on an operating channel. The amplifying transistor operates in a multi-channel system, where the bias current for the amplifying transistor operating at channels at an edge of a channel band is different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band.

1 . (canceled) 
     
     
         2 . A method comprising determining a bias current for an amplifying transistor based at least in part on an operating channel, the bias current for the amplifying transistor operating at channels at an edge of a channel band being different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band. 
     
     
         3 . The method of  claim 2  wherein the amplifying transistor is configured to operate in a multi-channel system. 
     
     
         4 . The method of  claim 2  further comprising providing the bias current to the amplifying transistor through a control signal. 
     
     
         5 . The method of  claim 4  wherein the control signal includes a digital control signal. 
     
     
         6 . The method of  claim 2  further comprising determining matching characteristics of a matching circuit that is configured to provide impedance matching between an output port of the amplifying transistor and a load. 
     
     
         7 . The method of  claim 6  wherein the matching characteristics are based at least in part on a transmission power level of the amplifying transistor. 
     
     
         8 . The method of  claim 6  wherein the matching characteristics are based at least in part on an operating channel of the amplifying transistor. 
     
     
         9 . The method of  claim 6  wherein the matching characteristics for the matching circuit when the amplifying transistor is operating at channels at an edge of a channel band are different from the matching characteristics for the matching circuit when the amplifying transistor is operating at channels nearer a center of the channel band. 
     
     
         10 . The method of  claim 2  wherein determining the bias current for the amplifying transistor based at least in part on the operating channel includes determining the bias current for the amplifying transistor based at least in part on the operating channel, an error vector magnitude target, and an operating point of the amplifying transistor. 
     
     
         11 . The method of  claim 2  wherein the bias current is determined to improve an operation efficiency off a mobile device that includes the amplifying transistor. 
     
     
         12 . A method comprising:
 receiving at a control circuit an indication of transmission power of an amplifier circuit; and   determining a control signal based at least in part on the indication of transmission power and operating requirements of the amplifier circuit to control a bias current provided to an amplifying transistor of the amplifier circuit, the bias current for the amplifying transistor operating at channels at an edge of a channel band being different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band.   
     
     
         13 . The method of  claim 12  further comprising adjusting the bias current according to the control signal. 
     
     
         14 . The method of  claim 12  further comprising controlling with the control signal an operating point of the amplifying transistor. 
     
     
         15 . The method of  claim 12  wherein the operating requirements of the amplifier circuit include at least one of a standard, a channel, a channel bandwidth, out-of-band spectral requirements, spectral mask requirements, an error vector magnitude, a modulation rate, and a modulation type. 
     
     
         16 . The method of  claim 12  wherein the control signal includes a digital control signal. 
     
     
         17 . The method of  claim 12  further comprising selecting the bias current from a plurality of discrete bias currents, each of the discrete bias currents being selected for a different range of operation of the amplifying transistor. 
     
     
         18 . The method of  claim 12  wherein the control signal is determined to improve an operation efficiency of a mobile device that includes the amplifier circuit. 
     
     
         19 . The method of  claim 12  further comprising determining the control signal to control a matching circuit configured to match an impedance of an output port of the amplifier circuit. 
     
     
         20 . The method of  claim 19  further comprising adjusting the matching circuit according to the control signal. 
     
     
         21 . The method of  claim 19  further comprising selecting a matching condition of the matching circuit from a plurality of discrete matching conditions, each of the discrete matching conditions being selected for a different range of operation of the amplifier circuit.