US 10,716,080 B2
Calibration techniques for envelope tracking power amplifiers
Dan Wolberg, Moshav Yanov (IL); and Shai Rachamim, Yavne (IL)
Assigned to APPLE INC., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Feb. 9, 2016, as Appl. No. 15/19,421.
Prior Publication US 2017/0230924 A1, Aug. 10, 2017
Int. Cl. H04W 56/00 (2009.01); H03F 1/02 (2006.01); H03F 3/24 (2006.01); H03F 3/195 (2006.01)
CPC H04W 56/004 (2013.01) [H03F 1/0222 (2013.01); H03F 3/195 (2013.01); H03F 3/245 (2013.01); H04W 56/0065 (2013.01); H03F 2200/102 (2013.01); H03F 2200/336 (2013.01); H03F 2200/451 (2013.01)] 28 Claims
OG exemplary drawing
 
1. A method of calibrating a wireless transmitting device, comprising:
determining a propagation delay mismatch between a first test signal on a first signal path of the wireless transmitting device and a second test signal on a second signal path of the wireless transmitting device, wherein determining the propagation delay mismatch comprises:
transmitting the first test signal having a first frequency on the first signal path;
transmitting the second test signal having a second frequency different from the first frequency on the second signal path;
measuring a phase difference between the first test signal and the second test signal; and
determining a delay measurement between the first test signal and the
second test signal based at least in part on the measured phase difference;
determining the propagation delay mismatch using a difference between the delay measurement and a previously determined delay measurement; and
adjusting delay circuitry of at least one of the first signal path and the second signal path to compensate for the propagation delay mismatch.