Methods and apparatuses for digital pre-distortion

Abstract

A method is provided. The method, comprises: power amplifying, with at least two parallel power amplifiers, at least two pre-distorted signals each corresponding to a unique transmit band, wherein each power amplifier operates in a unique transmit band; and pre-distorting, with a single pre-distortion system, at least two signals in different transmit bands, where the pre-distortion of each of the at least two signals is based upon a portion of a corresponding power amplified, pre-distorted signal, and where the pre-distortion diminishes certain IMD products in the corresponding power amplified, pre-distorted signal.

The invention claimed is: 
     
       1. A system, comprising:
 pre-distortion circuitry comprising an output; 
 wherein the predistortion circuitry is configured to pre-distort at least two signals in different transmit bands; 
 a digital to analog converter comprising an input coupled to the output of the pre-distortion circuitry, and an output; 
 wherein the predistortion circuitry is further configured to skew a center frequency of a bandwidth in which pre-distortion is performed and which corresponds to includes one transmit band so that the a pre-distortion bandwidth covers corresponding uplink and downlink bands; 
 wherein the pre-distortion of each of the at least two signals is based upon a portion of a corresponding power amplified, pre-distorted signal, and where wherein the pre-distortion diminishes certain intermodulation distortion (IMD) products in each of the power amplified, pre-distorted signals predistortion bandwidth; 
 at least two power amplifier circuits, wherein each power amplifier circuit comprises an input and an output, and is configured to operate in a unique transmit band; 
 wherein each input of each power amplifier circuit is coupled in parallel to the output of the digital to analog converter; 
 wherein each output of each power amplifier circuit is coupled in parallel to one another; and 
 wherein the at least two power amplifier circuits are configured to power amplify at least two pre-distorted signals each corresponding to a the unique transmit band. 
 
     
     
       2. The system of  claim 1 , wherein the skewed center frequency is equidistant from center frequencies corresponding to the downlink band, and its corresponding uplink band. 
     
     
       3. The system of  claim 1 , further comprising a first duplexer comprising a first port, a second port, and a third port, where the first port of the first duplexer is coupled to the output of the digital to analog converter, the second port of the first duplexer is coupled to an input of a first power amplifier circuit of the at least two power amplifier circuits, and the third port is coupled to an input of a second power amplifier circuit of the at least two power amplifier circuits. 
     
     
       4. The system of  claim 3 , further comprising:
 a first coupler comprising a first port, a second port and a third port, where the first port of the first coupler is coupled to the output of the first power amplifier circuit; and 
 a second coupler comprising a first port, a second port and a third port, where the first port of the second coupler is coupled to the output of the second power amplifier circuit. 
 
     
     
       5. The system of  claim 1 , further comprising:
 at least one analog to digital converter coupled between outputs of each of the power amplifier circuits, and the DPD circuitry. 
 
     
     
       6. The system of  claim 5 , wherein the at least two signals are digital baseband data, the digital to analog converter comprises an up converter, and the at least one analog to digital converter comprises a down converter. 
     
     
       7. The system of  claim 1 , further comprising:
 a first receiver front end system comprising an input and an output; and 
 a second receiver front end system comprising an input and an output. 
 
     
     
       8. The system of  claim 7 , further comprising:
 a first coupler comprising a first port, a second port and a third port, where the first port of the first coupler is coupled to the output of a first power amplifier circuit of the at least two power amplifier circuits; 
 a second coupler comprising a first port, a second port and a third port, where the first port of the second coupler is coupled to the output of a second power amplifier circuit of the at least two power amplifier circuits; 
 a second duplexer comprising a first port, a second port, and a third port, where the first port of the second duplexer is coupled to the third port of the first coupler and the second port of the second duplexer is coupled to the third port of the second coupler; 
 a third duplexer comprising a first port, a second port, and a third port, where the first port of the third duplexer is coupled to an input of the first receiver front end system and the second port of the third duplexer is coupled to an input of the second receiver front end system; 
 a fourth duplexer comprising a first port, a second port, and a third port, where the first port of the fourth duplexer is coupled to the third port of the second duplexer and the second port of the fourth duplexer is coupled to the third port of the third duplexer; and 
 wherein the third port of the fourth duplexer is configured to be coupled to an antenna. 
 
     
     
       9. The system of  claim 1 , wherein the transmit band is also the receive band, and the system is configured to be used for time division duplexing. 
     
     
       10. A method for diminishing intermodulation distortion products, the method comprising:
 power amplifying, using a first power amplifier, a first pre-distorted signal in a first transmit band;   power amplifying, using a second power amplifier, a second pre-distorted signal in a second transmit band;   pre-distorting, with a single pre-distortion system, two signals in different transmit bands, wherein pre-distortion of each of the two signals is based upon a portion of a corresponding power amplified, pre-distorted signal; and   skewing, a center frequency of a bandwidth in which the pre-distortion is performed and which includes one transmit band so that a pre-distortion bandwidth covers corresponding uplink and downlink bands, where the pre-distortion diminishes intermodulation distortion products in the pre-distortion bandwidth.   
     
     
       11. The method of  claim 10 , wherein the two signals are digital baseband data, then up converting each pre-distorted signal prior to power amplification, and down converting a portion of each power amplified, pre-distorted signal prior to utilizing each portion of each power amplified, pre-distorted signal for pre-distortion. 
     
     
       12. The method of  claim 10 , wherein each pre-distorted signal, prior to power amplification, is a digital signal, then converting each digital signal to an analog signal prior to power amplification, and digitizing a portion of each power amplified, pre-distorted signal prior to utilizing the portion of each of the power amplified, pre-distortion signals for pre-distortion. 
     
     
       13. The method of  claim 12 , wherein digitizing the portion comprises selectively digitizing, with a single analog to digital converter, the portion of each the power amplified, pre-distorted signal prior to utilizing the portion of each of the power amplified, pre-distortion signals for pre-distortion. 
     
     
       14. The method of  claim 13 , wherein selectively digitizing with the single analog to digital converter, comprises selectively digitizing with the single analog to digital converter, a received signal during a time period for reception.