System for calibrating power amplifier
A system for calibrating a power amplifier (PA) includes a memory, a processor, a digital pre-distorter (DPD), and a data converter. The DPD includes a programming interface module, a pattern generator, a multiplier, and a pre-distorter module. The multiplier multiplies reference baseband stream data from the memory with pattern coefficient data generated by the pattern generator to generate shaped reference baseband stream data. The pre-distorter module generates pre-distorted shaped reference baseband stream data. The PA receives a low-power reference radio frequency (RF) signal corresponding to the pre-distorted shaped reference baseband stream data and generates a high-power reference RF signal. The processor receives and compares the pre-distorted shaped reference baseband stream data with amplified shaped reference baseband stream data corresponding to the high-power reference RF signal, and adjusts pre-distortion parameters in the pre-distorter module based on the comparison such that the PA generates a linear high-power RF signal.
1. A system for calibrating a power amplifier, comprising:
a memory for storing reference baseband stream data;
a digital pre-distorter (DPD), connected to the memory, wherein the DPD includes:
a programming interface module for storing a seed value, first and second coefficient sequence values, first and second mode control values, a step size value, a step count value, first and second repetition count values, and an interrupt status value;
a pattern generator connected to the programming interface module for receiving the seed value, the first and second coefficient sequence values, the first and second mode control values, the step size value, the step count value, and the first and second repetition count values, and generating pattern coefficient data;
a multiplier connected to the pattern generator and the memory for receiving the pattern coefficient data and the reference baseband stream data, respectively, and generating shaped reference baseband stream data; and
a pre-distorter module connected to the multiplier for receiving the shaped reference baseband stream data and generating pre-distorted shaped reference baseband stream data, wherein the memory stores the pre-distorted shaped reference baseband stream data;
a digital-to-analog converter (DAC) connected to the pre-distorter module for receiving the pre-distorted shaped reference baseband stream data and generating a pre-distorted shaped reference baseband signal;
a radio frequency (RF) mixer, connected to the DAC for receiving the pre-distorted shaped reference baseband signal and generating an RF shaped reference baseband signal, wherein the power amplifier is connected to the RF mixer for receiving the RF shaped reference baseband signal and generating an amplified RF shaped reference baseband signal, and wherein the RF mixer receives the amplified RF shaped reference baseband signal and generates an amplified shaped reference baseband signal;
an analog-to-digital converter (ADC) connected to the RF mixer for receiving the amplified shaped reference baseband signal and generating amplified shaped reference baseband stream data; and
a processor connected to the ADC and the memory for receiving the amplified shaped and pre-distorted shaped reference baseband stream data, respectively, generating comparison data based on the amplified shaped and pre-distorted shaped reference baseband stream data, and adjusting a plurality of pre-distortion parameters based on the comparison data, thereby calibrating the power amplifier.
2. The system of claim 1 , wherein the pre-distorter module further includes a look-up table (LUT) for storing the plurality of pre-distortion parameters.
3. The system of claim 2 , wherein the processor is further connected to the pre-distorter module for adjusting the plurality of pre-distortion parameters.
4. The system of claim 3 , wherein the RF mixer further receives an RF signal and generates an analog baseband signal, and wherein the ADC receives the analog baseband signal and generates baseband stream data.
5. The system of claim 4 , wherein the processor further receives the baseband stream data, checks a presence of user-data in the baseband stream data, and adjusts the plurality of pre-distortion parameters when the first baseband stream data does not include user-data.
6. The system of claim 1 , wherein the programming interface module further generates an interrupt status signal when the plurality of pre-distortion parameters are adjusted.
7. The system of claim 1 , wherein the programming interface module includes:
a seed control register for storing the seed value;
a first calibration register for storing the first coefficient sequence value and the first repetition count value;
a calibration mode control register for storing the first and second mode control values;
a second calibration register for storing the step size value, the step count value, the second coefficient sequence value and the second repetition count value; and
an interrupt status register for storing the interrupt status value.
8. The system of claim 7 , wherein the pattern generator includes:
a linear feedback shift register (LFSR), connected to the seed control register and the first calibration register for receiving the seed value, the first coefficient sequence value, and the first repetition count value and generating LFSR sequence data;
a step-wise linear shaping module, connected to the second calibration register and the calibration mode control register for receiving the step size value, the step count value, the second coefficient sequence value, the second repetition count value, and the second mode control value, and generating stepwise sequence data; and
a multiplexer having a first input terminal connected to the LFSR for receiving the LFSR sequence data, a second input terminal connected to the step-wise linear shaping module for receiving the stepwise sequence data, a select input terminal connected to the calibration mode control register for receiving the first mode control value, and an output terminal for outputting at least one of the LFSR sequence and stepwise sequence data as the pattern coefficient data.
9. The system of claim 8 , wherein the multiplexer outputs the stepwise sequence data for at least one of increasing and decreasing an amplitude of the shaped reference baseband signal by way of the second mode control value.
10. The system of claim 1 , further comprising an event control module connected to the DPD for generating and providing a start trigger signal to the DPD, and wherein the DPD generates the pattern coefficient data based on the start trigger signal.
11. A radio-frequency (RF) transceiver, comprising:
a baseband processing unit, including:
a memory for storing first baseband stream data;
a processor for generating a control start trigger signal;
an event control module connected to the processor for receiving the control start trigger signal and generating a start trigger signal; and
a digital pre-distorter (DPD) connected to the memory and the event control module for receiving the first baseband stream data and the start trigger signal, respectively, and generating pre-distorted second baseband stream data, wherein the memory stores the pre-distorted second baseband stream data;
a radio-frequency integrated circuit (RFIC) connected to the baseband processing unit, wherein the RFIC includes:
a data converter connected to the DPD for receiving the pre-distorted second baseband stream data and generating a pre-distorted shaped reference baseband signal; and
an RF mixer connected to the data converter for receiving the pre-distorted shaped reference baseband signal and generating an RF shaped reference baseband signal;
a power amplifier connected to the RF mixer for receiving the RF shaped reference baseband signal and generating an amplified RF shaped reference baseband signal, wherein the RF mixer receives the amplified RF shaped reference baseband signal and generates an amplified shaped reference signal, and wherein the data converter receives the amplified shaped reference signal and generates third baseband stream data, wherein the processor receives the pre-distorted second and third baseband stream data, generates comparison data, and adjusts a plurality of pre-distortion parameters based on the comparison data, thereby calibrating the power amplifier,
wherein the RF mixer further receives an RF signal and generates an analog baseband signal, and the data converter further receives the analog baseband signal and generates baseband stream data, and wherein the DPD includes: a programming interface module for storing a seed value, first and second coefficient sequence values, first and second mode control values, a step size value, a step count value, first and second repetition count values, and an interrupt status values; and a pattern generator connected to the programming interface module for receiving the seed value, the first and second coefficient sequence values, the first and second mode control values, the step size value, the step count value, the first and second repetition count values, and generating pattern coefficient data.
12. The RF transceiver of claim 11 , wherein the DPD includes:
a multiplier connected to the pattern generator and the memory for receiving the pattern coefficient data and the first baseband stream data, respectively, and generating the second baseband stream data; and
a pre-distorter module connected to the multiplier for receiving the second baseband stream data and generating the pre-distorted second baseband stream data.
13. The RF transceiver of claim 12 , wherein the programming interface module includes:
a seed control register for storing the seed value;
a first calibration register for storing the first coefficient sequence value and the first repetition count value;
a calibration mode control register for storing the first and second mode control values;
a second calibration register for storing the step size value, the step count value, the second coefficient sequence value and the second repetition count value; and
an interrupt status register for storing the interrupt status value.
14. The RF transceiver of claim 13 , wherein the pattern generator includes:
a linear feedback shift register (LFSR) connected to the seed control register and the first calibration register for receiving the seed value, the first coefficient sequence value, and the first repetition count value and generating LFSR sequence data;
a stepwise linear shaping module connected to the second calibration register and the calibration mode control register for receiving the step size value, the step count value, the second coefficient sequence value, the second repetition count value, and the second mode control value, and generating stepwise sequence data; and
a multiplexer having a first input terminal connected to the LFSR for receiving the LFSR sequence data, a second input terminal connected to the stepwise linear shaping module for receiving the stepwise sequence data, a select input terminal connected to the calibration mode control register for receiving the first mode control value, and an output terminal for outputting at least one of the LFSR sequence and stepwise sequence data as the pattern coefficient data.
15. The RF transceiver of claim 14 , wherein the multiplexer outputs the stepwise sequence data for at least one of increasing and decreasing an amplitude of the shaped reference baseband signal by way of the second mode control value.
16. The RF transceiver of claim 14 , wherein the pre-distorter module further includes a look-up table (LUT), and wherein the LUT stores the plurality of pre-distortion parameters.
17. The RF transceiver of claim 16 , wherein the processor is further connected to the pre-distorter module for adjusting the plurality of pre-distortion parameters.
18. The RF transceiver of claim 11 , wherein the processor further receives the baseband stream data, checks a presence of user-data in the baseband stream data, and adjusts the plurality of pre-distortion parameters when the baseband stream data does not include user-data.
19. A method for calibrating a power amplifier, comprising:
storing first baseband stream data;
storing a seed value, first and second coefficient sequence values, first and second mode control values, a step size value, a step count value, first and second repetition count values, and an interrupt status value;
generating pattern coefficient data based on the seed value, the first and second coefficient sequence values, the first and second mode control values, the step size value, the step count value, and the first and second repetition count values;
generating second baseband stream data;
generating pre-distorted second baseband stream data based on the second baseband stream data;
generating a pre-distorted shaped reference baseband signal based on the pre-distorted second baseband stream data and the pattern coefficient data;
generating an RF shaped reference baseband signal based on the pre-distorted shaped reference baseband signal;
generating an amplified RF shaped reference baseband signal based on the RF shaped reference baseband signal;
generating an amplified shaped reference baseband signal based on the amplified RF shaped reference baseband signal;
generating third baseband stream data based on the amplified shaped reference baseband signal;
generating comparison data based on the pre-distorted second and third baseband stream data; and
adjusting a plurality of pre-distortion parameters based on the comparison data, thereby calibrating the power amplifier.