Power amplifier systems with load control

Abstract

A power amplification system is provided comprising: a power amplifier circuit; an output power control circuit for providing a plurality of values of capacitance, and a balun coupled to the power amplifier circuit and to the output power control circuit. The output power control circuit includes at least one load control capacitor. Each of the at least one load control capacitors is coupled to a load control switch for regulating the current path to and/or from the corresponding capacitor to control the value of the capacitance provided by the output power control circuit. A wireless device comprising such a power amplification system is also provided. A wireless module comprising such a power amplification system is also provided.

What is claimed is: 
     
         1 . A power amplification system comprising:
 a power amplifier circuit;   an output power control circuit that provides a plurality of values of capacitance, the output power control circuit including at least one load control capacitor coupled to a load control switch to control a value of the capacitance provided by the output power control circuit; and   a balun coupled to the power amplifier circuit and to the output power control circuit.   
     
     
         2 . The power amplification system of  claim 1  wherein the power amplifier circuit comprises a push-pull amplifier. 
     
     
         3 . The power amplification system of  claim 1  wherein at least two transistors of the power amplifier circuit are differential transistors. 
     
     
         4 . The power amplification system of  claim 3  wherein at least one of the at least two transistors is a heterojunction bipolar transistor. 
     
     
         5 . The power amplification system of  claim 3  wherein the balun comprises a first coil having a first end and a second end, the first end of the first coil being coupled to a first differential transistor and the second end of the first coil being coupled to a second differential transistor. 
     
     
         6 . The power amplification system of  claim 5  wherein the first end of the first coil is coupled to a drain or a collector of the first differential transistor and the second end of the first coil is coupled to a drain or a collector of the second differential transistor. 
     
     
         7 . The power amplification system of  claim 1  wherein the balun comprises a second coil having a first end and a second end, the first end of the second coil being coupled to an RF output node and the second end of the second coil being coupled to a ground. 
     
     
         8 . The power amplification system of  claim 7  wherein the second end of the second coil is coupled to the ground via one or more termination capacitors. 
     
     
         9 . The power amplification system of  claim 8  wherein at least one of the one or more termination capacitors is a surface-mount capacitor. 
     
     
         10 . The power amplification system of  claim 8  wherein the output power control circuit is coupled with at least one of the one or more termination capacitors. 
     
     
         11 . The power amplification system of  claim 10  wherein at least one of the one or more load control capacitors and at least one of the one or more termination capacitors are connected in parallel. 
     
     
         12 . The power amplification system of  claim 8  wherein a capacitance of the balun is dependent on one or more of: a value of the one or more termination capacitors of the balun, a value of the capacitance provided by the output power control circuit, whether the one or more termination capacitors and the output power control circuit is connected in parallel or in series, and whether the load control switch is on or off. 
     
     
         13 . The power amplification system of  claim 1  wherein the output power control circuit provides low capacitance having a value close to zero when the load control switch is off. 
     
     
         14 . The power amplification system of  claim 1  wherein, when the load control switch is off, the output power control circuit does not provide additional capacitance to the balun, and the power amplification system has a load impedance value that leads to a lower output power. 
     
     
         15 . The power amplification system of  claim 1  wherein, when the load control switch is on, the output power control circuit provides additional capacitance to the balun, causing a load impedance value to decrease and output power of the power amplification system to increase to a higher output power. 
     
     
         16 . The power amplification system of  claim 1  wherein the power amplification system comprises and/or is connected to one or more power amplifier components configured to provide at least one of advanced power tracking and envelop tracking. 
     
     
         17 . The power amplification system of  claim 1  wherein one or more part of the output power control circuit is controlled by a CMOS control, the CMOS control being configured receive band and/or power mode controls over a MIPI digital interface. 
     
     
         18 . The power amplification system of  claim 1  comprising a frequency response compensation circuit that provides a plurality of values of capacitance, the frequency response compensation circuit including at least one tuning capacitor coupled to a switch to control a value of the capacitance provided by the frequency response compensation circuit, and the frequency response compensation circuit being coupled to at least two transistors of the power amplifier circuit, the frequency response compensation circuit configured to reduce variation over frequency of a load impedance of the power amplification system. 
     
     
         19 . A wireless device comprising:
 a memory;   a user interface;   a baseband sub-system;   a transceiver;   a power management component; and   a power amplification system, the power amplification system including a power amplifier circuit, an output power control circuit that provides a plurality of values of capacitance, the output power control circuit having at least one load control capacitor coupled to a load control switch to control a value of the capacitance provided by the output power control circuit, and a balun coupled to the power amplifier circuit and to the output power control circuit.   
     
     
         20 . A wireless module comprising:
 a packaging substrate;   one or more surface-mount devices;   a duplexer assembly;   a front-end power management integrated circuit;   a match component;   an antenna switch module; and   a power amplifier assembly including a power amplification system, the power amplification system having a power amplifier circuit, and an output power control circuit providing a plurality of values of capacitance, the output power control circuit having at least one load control capacitor coupled to a load control switch to control the value of the capacitance provided by the output power control circuit, and a balun coupled to the power amplifier circuit and to the output power control circuit.