Automated envelope tracking system

Patent metadata

Field	Value
Publication number	US-10270394-B2
Application number	US-201615392186-A
Country	US
Kind code	B2
Filing date	Dec 28, 2016
Priority date	Dec 30, 2015
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

First claim

What is claimed is:

1. An envelope tracking system comprising:
a signal measuring device configured to determine a size of a radio frequency input signal;
a bit-encoder configured to encode an envelope tracking control signal to obtain an encoded envelope tracking control signal, the envelope tracking control signal based at least in part on the size of the radio frequency input signal, the signal measuring device and the bit-encoder included in a transceiver; and
an envelope tracker configured to provide a supply voltage to a power amplifier, the supply voltage based at least in part on the encoded envelope tracking control signal, the envelope tracker included in a radio frequency front end module that is separate from the transceiver and communicates with the transceiver via a pair of low-voltage digital differential signaling lines.

2. The envelope tracking system of claim 1 wherein the signal measuring device determines the size of the radio frequency input signal by determining an amplitude of I and Q components of a baseband signal associated with the radio frequency input signal.

3. The envelope tracking system of claim 2 wherein determining the amplitude of the radio frequency input signal includes obtaining the absolute value of the amplitude of the I and Q components associated with the radio frequency input signal.

4. The envelope tracking system of claim 1 wherein the signal measuring device implements a coordinate rotation digital computer algorithm.

5. The envelope tracking system of claim 1 wherein the bit-encoder includes a sigma-delta modulator.

6. The envelope tracking system of claim 1 further comprising a lookup table storing a plurality of envelope tracking control values.

7. The envelope tracking system of claim 6 wherein the envelope tracking control signal is generated based at least in part on the size of the radio frequency input signal or a selection of an envelope tracking control value from the plurality of envelope tracking control values.

8. The envelope tracking system of claim 1 further comprising the pair of low-voltage digital differential signaling lines configured to communicate the encoded envelope tracking control signal from the bit-encoder to the envelope tracker.

9. The envelope tracking system of claim 1 wherein the envelope tracker includes a digital to analog converter configured to convert the encoded envelope tracking control signal to an analog signal.

10. The envelope tracking system of claim 1 wherein the envelope tracker includes a driver configured to generate the supply voltage.

11. The envelope tracking system of claim 1 wherein the size of the radio frequency input signal includes an instantaneous amplitude of the radio frequency input signal.

12. The envelope tracking system of claim 1 wherein the radio frequency front end module is one of a plurality of radio frequency front end modules in communication with the transceiver.

13. The envelope tracking system of claim 1 where in the transceiver is spatially separated from at least one of the plurality of radio frequency front end modules resulting in different length low-voltage digital differential signaling lines between the transceiver and at least one of the plurality of radio frequency front end modules.

14. A wireless device comprising:
a transceiver including a signal measuring device and a bit-encoder, the signal measuring device configured to determine a size of a radio frequency input signal, and the bit-encoder configured to encode an envelope tracking control signal to obtain an encoded envelope tracking control signal, the envelope tracking control signal based at least in part on the size of the radio frequency input signal; and
a radio frequency front-end module in communication with the transceiver, the radio frequency front-end module including an envelope tracker configured to provide a supply voltage to a power amplifier, the supply voltage based at least in part on the encoded envelope tracking control signal, the wireless device including a plurality of radio frequency front-end modules, at least one of the radio frequency front-end modules including one or more power amplifiers configured to process signals of a different frequency band than at least one other of the radio frequency front-end modules, the plurality of radio frequency front-end modules being in communication with the transceiver via a plurality of pairs of low-voltage digital differential signaling lines, and at least one of the pairs of low-voltage digital differential signaling lines being of a different length than at least one other pair of low-voltage digital differential signaling lines.

15. The wireless device of claim 14 wherein the bit-encoder includes a sigma-delta modulator.

16. The wireless device of claim 14 wherein the transceiver further includes a non-volatile storage configured to store a mapping of a plurality of radio frequency input size values to a plurality of envelope tracking control values.

17. The wireless device of claim 16 wherein the envelope tracking control signal is determined based at least in part on the size of the radio frequency input signal and the mapping of the plurality of radio frequency input size values to the plurality of envelope tracking control values.

18. The wireless device of claim 14 wherein the envelope tracker includes a digital to analog converter configured to convert the encoded envelope tracking control signal to an analog signal.

19. The wireless device of claim 14 wherein the envelope tracker includes a driver configured to modify a voltage received from a battery to obtain the supply voltage for the power amplifier.

20. A method of envelope-tracking a radio frequency signal, the method comprising:
receiving I and Q components of a radio frequency signal at a modulator of a transceiver;
determining an expected size of the radio frequency signal based on a measurement of the I and Q components;
determining a control signal based at least in part on the expected size of the RF signal, the control signal indicating a voltage envelope for the radio frequency signal;
converting the control signal to a low-voltage digital differential signaling format using a digital bit encoder to obtain an encoded control signal; and
transmitting via a pair of low-voltage digital differential signaling lines the encoded control signal to an envelope tracker of a radio frequency front-end module that is on a separate die from the transceiver.

21. The method of claim 20 wherein, in response to providing the encoded control signal to the envelope tracker, the method further comprises:
modifying a device supply voltage based at least in part on the encoded control signal; and
providing the modified device supply voltage to a power amplifier that receives the radio frequency signal.

Assignees

• Skyworks Solutions Inc

Inventors

• Drogi Serge Francois
• Balteanu Florinel G
• Panseri Luigi
• Christmas Craig Joseph
• Dicarlo Paul T

Classifications

• H03F1/565

  using inductive elements · CPC title

• H03F1/0227 Primary

  using supply converters · CPC title

• H03F3/245

  with semiconductor devices only · CPC title

• H03F3/191

  Tuned amplifiers (H03F3/193, H03F3/195 take precedence) · CPC title

• H03F2200/102

  A non-specified detector of a signal envelope being used in an amplifying circuit · CPC title