US 9,813,169 B2
Precision measurement of transmit power using loopback calibration in an RF transceiver
Josef Einzinger, Georgensgmünd (DE); and Sudipto Chakraborty, Plano, TX (US)
Assigned to TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US); and TEXAS INSTRUMENTS DEUTSCHLAND GMBH, Freising (DE)
Filed by Texas Instruments Deutschland GmbH, Freising (DE); and Texas Instruments Incorporated, Dallas, TX (US)
Filed on Nov. 19, 2015, as Appl. No. 14/946,360.
Prior Publication US 2017/0149512 A1, May 25, 2017
Int. Cl. H04W 52/08 (2009.01); H04B 17/13 (2015.01); H04B 1/40 (2015.01); H04W 52/52 (2009.01)
CPC H04B 17/13 (2015.01) [H04B 1/40 (2013.01); H04W 52/08 (2013.01); H04W 52/52 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method of calibrating a transmit power of a communications transceiver, comprising:
transmitting a periodic signal at a selected frequency from a transmit channel in the transceiver, at a first programmed power setting;
measuring a first power level of the transmitted signal as amplified by a receive amplifier in a receive channel of the transceiver, the first power level proportional to a gain of the receive amplifier;
measuring a second power level of the transmitted signal as received by the receive channel of the transceiver and bypassing the receive amplifier;
producing, from the transmitted signal as received by a loopback reference channel in the transceiver, a processed signal at an amplitude proportional to a regulated voltage;
measuring a third power level of the processed signal;
calculating the gain of the receive amplifier from a ratio of the first and second power levels; and
calculating an absolute power level corresponding to the first programmed power setting from a ratio of the second and third power levels;
wherein the transmit power of the communications transceiver is calibrated based on the absolute power.