WIRELESS TRANSMITTER CALIBRATION USING DEVICE RECEIVER

• US 20100144286A1
• Filed: 12/08/2008
• Published: 06/10/2010
• Est. Priority Date: 12/08/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Sorensen, Robert
• Granted Patent: US 8,116,703 B2
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 2200/105 A non-specified detector of the power of a signal being used in an amplifying circuit
• CPC Class Codes: H03F 2200/204 A hybrid coupler being used at the output of an amplifier circuit
• CPC Class Codes: H03F 2200/321 Use of a microprocessor in an amplifier circuit or its control circuit
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/408 the output amplifying stage of an amplifier comprising three power stages
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements

Abstract

Portable electronic devices are provided that contain radio-frequency transceiver circuitry. Power amplifier circuitry may amplify transmitted radio-frequency signals from the radio-frequency transceiver circuitry. The power amplifier circuitry may be powered with a power supply voltage. The power supply voltage may be reduced to conserve power provided that requirements such as adjacent channel leakage ratio requirements are satisfied. Calibration measurements may be made to determine the extent to which power can be conserved by power supply voltage reductions. During calibration, the transceiver circuitry may transmit signals in a transmit subband. Test equipment that is external to the device may frequency shift the transmitted signals into a receive subband. The frequency-shifted signals may be fed back into the device. The transceiver circuitry in the device may make power measurements on the fed back signals. The power measurements may be used to compute adjacent channel leakage ratio values.

Claims

1. A method for using test equipment to calibrate a portable electronic device that contains wireless circuitry, comprising:

transmitting radio-frequency signals from transceiver circuitry in the electronic device to the test equipment; and

with the transceiver circuitry in the electronic device, measuring a power level associated with a fed-back version of the transmitted radio-frequency signals received from the test equipment.

2. The method defined in claim 1 wherein the electronic device comprises a duplexer and wherein transmitting the radio-frequency signals comprises transmitting the radio-frequency signals from the transceiver circuitry through the duplexer and wherein measuring the power level comprises receiving the fed-back version of the transmitted radio-frequency signals through the duplexer.

3. The method defined in claim 1 wherein the wireless circuitry handles signals associated with a communications band that includes a transmit subband and a receive subband, wherein transmitting the radio-frequency signals comprises transmitting a given signal in the transmit subband, and wherein measuring the power level comprises measuring a power level associated with a fed-back version of the given signal that has been frequency shifted to fall in the receive subband.

4. The method defined in claim 1 wherein the test equipment includes frequency shifting equipment that shifts the transmitted radio-frequency signals in frequency to produce frequency-shifted transmitted radio-frequency signals, and wherein measuring the power level comprises measuring the power level of a fed-back version of the frequency-shifted transmitted radio-frequency signals.

5. The method defined in claim 1 wherein the wireless circuitry includes an adjustable power supply that produces a power supply voltage, wherein the wireless circuitry includes a power amplifier that produces the transmitted radio-frequency signals, and wherein transmitting the radio-frequency signals comprises transmitting the radio-frequency signals while adjusting the power supply voltage with the adjustable power supply to identify minimum acceptable power supply voltage levels while meeting performance criteria for the wireless circuitry.

6. The method defined in claim 5 wherein the test equipment includes frequency shifting equipment that shifts the frequency of the transmitted radio-frequency signals to produce frequency-shifted transmitted radio-frequency signals, and wherein measuring the power level comprises measuring the power level of a fed-back version of the frequency-shifted transmitted radio-frequency signals.

7. A method for calibrating a wireless electronic device having at least one antenna, transceiver circuitry, a radio-frequency power amplifier, and an adjustable power supply that supplies the radio-frequency power amplifier with an adjustable power supply voltage, comprising:

with the radio-frequency power amplifier, amplifying radio-frequency signals from the transceiver circuitry at a given frequency to be transmitted through the antenna;

with the adjustable power supply, providing an adjustable power supply voltage to the radio-frequency power amplifier that varies as a function of the given frequency; and

with the transceiver circuitry, making a power measurement on a fed-back version of the amplified radio-frequency signals that is received from test equipment.

8. The method defined in claim 7 wherein the test equipment includes a directional coupler that receives the amplified radio-frequency signals from the power amplifier and wherein making the power measurement comprises:

with the transceiver circuitry, making a power measurement on the fed-back version of the amplified radio-frequency signals by measuring the amplified radio-frequency signals after the amplified radio-frequency signals have passed through the directional coupler.

9. The method defined in claim 8 wherein the test equipment includes a signal generator that supplies a signal generator output signal and a mixer that receives the amplified radio-frequency signals from the directional coupler at a first input, that receives the signal generator output signal at a second input, and that produces a frequency-shifted version of the amplified radio-frequency signals at an output, the method further comprising:

providing the frequency-shifted version of the amplified radio-frequency signals from the output to the directional coupler.

10. The method defined in claim 9 further comprising:

feeding back the frequency-shifted version of the amplified radio-frequency signals to the wireless electronic device with the directional coupler to form the fed-back version of the amplified radio-frequency signals.

11. The method defined in claim 7 further comprising:

storing calibration data in the wireless electronic device that is based on the power measurements made with the transceiver circuitry.

12. The method defined in claim 11 further comprising:

while operating the wireless electronic device, controlling the transceiver circuitry and the power amplifier based on the stored calibration data to ensure that performance criteria for the wireless electronic device are satisfied while minimizing power consumption.

13. The method defined in claim 12 wherein controlling the transceiver circuitry and the power amplifier comprises:

minimizing the adjustable power supply voltage supplied to the radio-frequency power amplifier based on the stored calibration data while satisfying adjacent channel leakage ratio requirements.

14. The method defined in claim 7 further comprising:

shifting the amplified radio-frequency signals to multiple different receiver channels using the test equipment.

15. The method defined in claim 7 further comprising:

computing adjacent channel leakage ratio values based on the power measurements made by the transceiver circuitry.

16. The method defined in claim 7 wherein the fed-back version of the amplified radio-frequency signals has an associated frequency in a cellular telephone receive subband, the method further comprising:

using a mixer and a signal generator in the test equipment to adjust the associated frequency while the transceiver circuitry is making the power measurement on the fed-back version of the amplified radio-frequency signals.

17. A portable electronic device, comprising:

an antenna;

radio-frequency transceiver circuitry coupled to the antenna;

a radio-frequency power amplifier that amplifies radio-frequency signals from the radio-frequency transceiver circuitry;

adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier; and

storage and processing circuitry that adjusts the adjustable power supply voltage supplied by the adjustable power supply circuitry to the radio-frequency power amplifier based on calibration data, wherein the calibration data is based on calibration measurements made using receiver circuitry in the radio-frequency transceiver circuitry.

18. The portable electronic device defined in claim 17 further comprising a connector, wherein the amplified radio-frequency signals are output from the radio-frequency power amplifier, wherein the amplified radio-frequency signals are supplied to test equipment through the connector, and wherein a frequency-shifted version of the amplified radio-frequency signals is fed back to the transceiver circuitry through the connector.

19. The portable electronic device defined in claim 18 wherein the receiver circuitry is configured to make power measurements for computing adjacent channel leakage ratio values using the frequency-shifted version of the amplified radio-frequency signal.

20. The portable electronic device defined in claim 17 wherein the storage and processing circuitry is configured to store power supply voltage offset versus frequency data as part of the calibration data and wherein the storage and processing circuitry uses the stored power supply voltage offset data in adjusting the adjustable power supply voltage.