Electronic device with data-rate-dependent power amplifier bias

• US 8,165,642 B2
• Filed: 05/13/2009
• Issued: 04/24/2012
• Est. Priority Date: 05/13/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Dimpflmaier, Ronald W., Kong, Daniel C.
• Primary Examiner(s): LAUTURE, JOSEPH J
• Application Number:
  US12/465,260
• Publication Number:
  US 20100291975A1
• Time in Patent Office: 1,077 Days
• Field of Search: 455/572, 455/569, 455/563, 455/557, 455/556, 455/517, 455/88, 455/90, 455/575, 455/345, 455/550
• US Class Current: 455/572
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

Wireless circuitry in an electronic device may contain output power amplifier circuitry for amplifying transmitted radio-frequency signals. The power amplifier circuitry may be powered using a bias voltage. The magnitude of the bias voltage can be selectively reduced to conserve power. Control circuitry can maintain a table of bias voltage settings to use under various conditions. These conditions may include required output powers as determined by link quality, transmission mode status, and required data rates. When link quality is low or when high data rates are required, the bias voltage can be maintained at a relatively high level to ensure that the power amplifier operates linearly and does not exhibit excessive noise. When link quality is high or when data rates are low as with voice calls, the bias voltage can be reduced to conserve power.

Claims

1. Wireless communications circuitry on a portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals that are transmitted from the portable electronic device at a data transmission rate;

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

storage and processing circuitry that directs the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on the data transmission rate, wherein the storage and processing circuitry comprises a cubic metric calculator that calculates a cubic metric for the radio-frequency signals that are transmitted and wherein the storage and processing circuitry directs the adjustable power supply circuitry to supply the adjustable power supply voltage based at least partly on the cubic metric.

2. The wireless communications circuitry defined in claim 1 wherein the storage and processing circuitry further comprises a digital-to-analog converter that supplies an analog control signal to the adjustable power supply circuitry based at least partly on the cubic metric.

3. The wireless communications circuitry defined in claim 1 wherein the storage and processing circuitry stores a look-up table that the storage and processing uses in determining appropriate levels for the adjustable power supply voltage.

4. Wireless communications circuitry on a portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals that are transmitted from the portable electronic device at a data transmission rate;

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

storage and processing circuitry that directs the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on the data transmission rate, wherein the storage and processing circuitry further comprises a digital-to-analog converter that supplies an analog control signal to the adjustable power supply circuitry based at least partly on the data transmission rate.

5. Wireless communications circuitry on a portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals that are transmitted from the portable electronic device at a data transmission rate;

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

storage and processing circuitry that directs the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on the data transmission rate, wherein the radio-frequency signals comprise voice data when the wireless communications circuitry is operated in a first mode, wherein the radio-frequency signals comprise high-speed uplink packet access data with a data upload rate of greater than 5 Mbps when the wireless communications circuitry is operated in a second mode, and wherein the storage and processing circuitry is configured to direct the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a lower value during the first mode than during the second mode.

6. The wireless communications circuitry defined in claim 5 wherein the wireless communications circuitry operates using power from a battery, the wireless communications circuitry further comprising:

a battery input in the adjustable power supply circuitry that receives a battery voltage from the battery; and

a power supply voltage output at which the adjustable power supply voltage is supplied to the radio-frequency power amplifier circuitry, wherein the adjustable power supply voltage is less than the battery voltage.

7. An electronic device, comprising:

radio-frequency input-output circuitry that supplies radio-frequency signals to be wirelessly transmitted from the electronic device to external equipment;

radio-frequency power amplifier circuitry that amplifies the radio-frequency signals;

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

storage and processing circuitry that determines whether the electronic device is operating in a voice mode or a data mode and that directs the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on whether the electronic device is determined to be operating in the voice mode or is determined to be operating in the data mode.

8. The electronic device defined in claim 7 wherein the data mode comprises a high-speed uplink packet access data mode in which the radio-frequency signals include data uploaded at a data rate of at least 5 Mbps.

9. The electronic device defined in claim 8 wherein the voice mode comprises a mode in which the radio-frequency signals represent data uploaded at a data rate of less than 100 kbps.

10. The electronic device defined in claim 7 wherein the storage and processing circuitry includes a cubic metric calculator that computes a cubic metric for the radio-frequency signals that are currently being transmitted and wherein the storage and processing circuitry is configured to direct the adjustable power supply circuitry to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on the computed cubic metric.

11. The electronic device defined in claim 10 wherein the storage and processing circuitry stores a look-up table that the storage and processing uses in determining appropriate levels for the adjustable power supply voltage.

12. The electronic device defined in claim 7 wherein the storage and processing circuitry stores a look-up table that the storage and processing uses in determining appropriate levels for the adjustable power supply voltage, wherein the storage and processing circuitry is configured to store voltage bias entries in the look-up table that vary as a function of a data transmission rate parameter associated with multiple different data transmission rates for the radio-frequency signals.

13. A portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals to be wirelessly transmitted from the portable electronic device;

storage and processing circuitry; and

adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier circuitry based on control signals received from the storage and processing circuitry, wherein the storage and processing circuitry directs the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on a data transmission rate parameter associated with the radio-frequency signals, wherein the portable electronic device comprises a cellular telephone and wherein the storage and processing circuitry comprises a cubic metric calculator that calculates the data rate transmission parameter.

14. A portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals to be wirelessly transmitted from the portable electronic device;

storage and processing circuitry; and

adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier circuitry based on control signals received from the storage and processing circuitry, wherein the storage and processing circuitry directs the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on a data transmission rate parameter associated with the radio-frequency signals, wherein;

the storage and processing circuitry is configured to determine when the portable electronic device is being operated in a voice mode in which the radio-frequency signals are being used to transmit data at less than 100 kbps and is configured to determine when the portable electronic device is being operated in a data mode in which the radio-frequency signals are being used to transmit data at more than 1 Mbps; and

the storage and processing circuitry is configured to direct the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier at a first level when the portable electronic device is in the voice mode and at a second level when the portable electronic device is in the data mode.

15. The portable electronic device defined in claim 14 wherein the first level is less than the second level.

16. the portable electronic device defined in claim 15 wherein the data rate transmission parameter comprises a cubic metric and wherein the storage and processing circuitry comprises a cubic metric calculator that calculates the cubic metric.

17. A portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals to be wirelessly transmitted from the portable electronic device;

storage and processing circuitry; and

adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier circuitry based on control signals received from the storage and processing circuitry, wherein the storage and processing circuitry directs the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on a data transmission rate parameter associated with the radio-frequency signals, wherein the storage and processing circuitry is configured to direct the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry based on desired output power levels for the radio-frequency power amplifier circuitry.

18. A portable electronic device, comprising:

radio-frequency power amplifier circuitry that amplifies radio-frequency signals to be wirelessly transmitted from the portable electronic device;

storage and processing circuitry; and

adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier circuitry based on control signals received from the storage and processing circuitry, wherein the storage and processing circuitry directs the adjustable power supply voltage to supply the adjustable power supply voltage to the radio-frequency power amplifier circuitry at a level that is selected based at least partly on a data transmission rate parameter associated with the radio-frequency signals, wherein the data transmission rate parameter comprises a cubic metric, wherein the storage and processing circuitry stores a look-up table that the storage and processing uses in determining appropriate levels for the adjustable power supply voltage, and wherein the look-up table includes voltage bias entries that vary as a function of desired output power levels for the radio-frequency power amplifier and that vary as a function of the cubic metric.