Transmitter first/second digital predistortion and first/second adaption circuitry with feedback
A method of predistorting an input signal ( 902 ) for an amplifier is disclosed (FIG. 9 ). The method includes predistorting the input signal with a first set of parameters (FDPD) and a second set of parameters (CDPD) at a first time ( 904 ). The first set of parameters is updated at a second time ( 914 ). The second set of parameters is updated separately from the first set of parameters at a third time ( 920 ).
1. A transmitter circuit comprising:
(A) an input lead coupled to a digital input signal;
(B) an output lead coupled to an amplified RF signal;
(C) first digital predistortion circuitry having a digital input coupled to the input lead, a parameter input receiving a first set of predistortion parameters, and an output;
(D) second digital predistortion circuitry having a digital input coupled to the output of the first digital predistortion circuitry, a parameter input receiving a second set of predistortion parameters, and an output coupled to the output lead;
(E) first adaption circuitry having a first error input coupled with the output lead and having a parameter output coupled with the parameter input of the first digital predistortion circuitry; and
(F) second adaption circuitry having a second error input coupled with the output lead and having a parameter output coupled with the parameter input of the second digital predistortion circuitry.
2. The transmitter circuit of claim 1 including first trigger circuitry having an input coupled to the digital input lead and a first trigger output, and in which the first digital predistortion circuitry has a trigger input coupled to the first trigger output.
3. The transmitter circuit of claim 1 including second trigger circuitry having an input coupled to the output of the first digital predistortion circuitry and a second trigger output, and in which the second digital predistortion circuitry has a trigger input coupled to the second trigger output.
4. The transmitter circuit of claim 1 including first trigger circuitry having an input coupled to the digital input lead and a first trigger output, and second trigger circuitry having an input coupled to the output of the first digital predistortion circuitry and a second trigger output, and in which the first digital predistortion circuitry has a trigger input coupled to the first trigger output, and in which the second digital predistortion circuitry has a trigger input coupled to the second trigger output, the first trigger circuitry producing an output signal on the first trigger output more frequently than the second trigger circuitry produces an output signal on the second trigger output.
5. The transmitter circuit of claim 1 including first delay circuitry having an input coupled to the input lead and a first delay output, and including first summing circuitry having a positive input coupled to the first delay output, a negative input coupled to the output lead, and a first error output coupled to the first error input.
6. The transmitter circuit of claim 1 including second delay circuitry having an input coupled to the output of the first digital predistortion circuitry and a second delay output, and including second summing circuitry having a positive input coupled to the second delay output, a negative input coupled to the output lead, and a second error output coupled to the second error input.
7. The transmitter circuit of claim 1 in which the second digital predistortion circuitry receives a second set of predistortion parameters larger than the first set of predistortion parameters received by the first digital predistortion circuitry.
8. The transmitter circuit of claim 1 including modulation circuitry and crest factor reduction circuitry coupling the input lead to the digital input of the first digital predistortion circuitry.
9. The transmitter circuit of claim 1 including digital to analog circuitry, RF UP circuitry, and power amplifier circuitry coupling the output of the second digital predistortion circuitry to the output lead.
10. The transmitter circuit of claim 1 including attenuation circuitry, RF DN circuitry and analog to digital circuitry coupling the output lead to the first error input and the second error input.