Quasi iso-gain supply voltage function for envelope tracking systems

• US 9,263,996 B2
• Filed: 07/19/2012
• Issued: 02/16/2016
• Est. Priority Date: 07/20/2011
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Folkmann, Andrew F., Retz, James M., Khlat, Nadim, Chiron, Jean-Frederic
• Primary Examiner(s): Tsai, Carol S. W.
• Application Number:
  US13/552,768
• Publication Number:
  US 20130024142A1
• Time in Patent Office: 1,307 Days
• Field of Search: 702/62, 702/64, 455/127.2, 455/226.1, 455/114.3, 455/115.1, 323/285, 323/286, 330/10, 330/2, 330/136, 330/129, 330/127, 330/199, 330/293, 330/131
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers

Abstract

A method of defining a quasi iso-gain supply voltage function for an envelope tracking system is disclosed. The method includes a step of capturing iso-gain supply voltage values versus power values for a device under test (DUT). Other steps involve locating a minimum iso-gain supply voltage value, and then replacing the iso-gain supply voltage values with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value. The method further includes a step of generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power for the DUT after the step of replacing the iso-gain supply voltage values with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value.

Claims

1. A method of defining a quasi iso-gain supply voltage function for an envelope tracking system comprising:

capturing into a memory array iso-gain supply voltage values versus output power values and input power values over a predetermined input power range for a device under test (DUT);

locating a minimum iso-gain supply voltage value within the memory array;

replacing the iso-gain supply voltage values within the memory array with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value;

generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power values from the iso-gain supply voltage values and input power values captured in the memory array; and

writing the LUT to a tangible computer-readable medium.

2. The method of claim 1 wherein the DUT is a power amplifier configured to operate in the envelope tracking system.

3. The method of claim 2 wherein the predetermined input power range is a predetermined supply voltage operating range of the envelope tracking system.

4. The method of claim 2 wherein quasi iso-gain supply voltage tracks instantaneous output power minimums for a gain target that is higher than a small signal gain of the power amplifier.

5. The method of claim 1 wherein a degradation of adjacent channel leakage ratio (ACLR) is less than 0.1 dB for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.

6. The method of claim 1 wherein a degradation of error vector magnitude (EVM) is less than 0.01% for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.

7. An automated test system (ATS) of defining a quasi iso-gain supply voltage function for an envelope tracking system comprising:

a system controller programmed to execute steps comprising;

capturing into a memory array iso-gain supply voltage values versus output power values and input power values over a predetermined input power range for a device under test (DUT);

locating a minimum iso-gain supply voltage value within the memory array;

replacing the iso-gain supply voltage values within the memory array with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value;

generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power values from the iso-gain supply voltage values and input power values captured in the memory array; and

writing the LUT to a tangible computer-readable medium.

8. The ATS of claim 7 wherein the DUT is a power amplifier configured to operate in the envelope tracking system.

9. The ATS of claim 8 wherein the predetermined input power range is a predetermined supply voltage operating range of the envelope tracking system.

10. The ATS of claim 8 wherein quasi iso-gain supply voltage tracks instantaneous output power minimums for a gain target that is higher than a small signal gain of the power amplifier.

11. The ATS of claim 7 wherein a degradation of adjacent channel leakage ratio (ACLR) is less than 0.1 dB for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.

12. The ATS of claim 7 wherein a degradation of error vector magnitude (EVM) is less than 0.01% for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.

13. A tangible computer-readable medium having computer instructions stored thereon, wherein the computer instructions are readable by a computing device of an automated test system (ATS) to perform operations for defining a quasi iso-gain supply voltage function for an envelope tracking system, the operations comprising:

capturing into a memory array iso-gain supply voltage values versus output power values and input power values over a predetermined input power range for a device under test (DUT);

locating a minimum iso-gain supply voltage value within the memory array within the predetermined input power range;

replacing the iso-gain supply voltage values within the memory array with the minimum iso-gain supply voltage value for corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value;

generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power values from the iso-gain supply voltage values and input power values captured in the memory array; and

writing the LUT to a tangible computer-readable medium.

14. The tangible computer-readable medium of claim 13 wherein the DUT is a power amplifier configured to operate in the envelope tracking system.

15. The tangible computer-readable medium of claim 14 wherein the predetermined input power range is a predetermined supply voltage operating range of the envelope tracking system.

16. The tangible computer-readable medium of claim 13 further comprising generating a look-up table (LUT) of iso-gain supply voltage values as a function of input power for the DUT after replacing the iso-gain supply voltage values with the minimum iso-gain supply voltage value for the corresponding output power values that are less than an output power value corresponding to the minimum iso-gain supply voltage value.

17. The tangible computer-readable medium of claim 14 wherein quasi iso-gain supply voltage tracks instantaneous output power minimums for a gain target that is higher than a small signal gain of the power amplifier.

18. The tangible computer-readable medium of claim 13 wherein a degradation of adjacent channel leakage ratio (ACLR) is less than 0.1 dB for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.

19. The tangible computer-readable medium of claim 13 wherein a degradation of error vector magnitude (EVM) is less than 0.01% for an envelope tracking transmit system employing the quasi iso-gain supply voltage function versus the envelope tracking system without employing the quasi iso-gain supply voltage function.