US 12,424,976 B2
System and method for adjusting amplifier bias current based on input signal envelope tracking
Ali Fard, Corona Del Mar, CA (US); and Mats Carlsson, Sundbyberg (SE)
Assigned to QUANTALRF AG, (CH)
Filed by QuantaIRF AG, Zurich (CH)
Filed on Feb. 9, 2022, as Appl. No. 17/668,298.
Claims priority of provisional application 63/147,668, filed on Feb. 9, 2021.
Prior Publication US 2022/0385238 A1, Dec. 1, 2022
Int. Cl. H03G 3/20 (2006.01); H03F 1/02 (2006.01); H03F 3/195 (2006.01); H03F 3/24 (2006.01)
CPC H03F 1/0222 (2013.01) [H03F 3/195 (2013.01); H03F 3/245 (2013.01); H03F 2200/102 (2013.01); H03F 2200/451 (2013.01); H03F 2200/537 (2013.01)] 26 Claims
OG exemplary drawing
 
14. A system, comprising:
an envelope detector configured to generate an envelope detection signal corresponding to an envelope of an input signal; and
an amplifier circuit coupled to the envelope detector and configured to provide an output signal in response to the input signal, the amplifier circuit including an amplifier and a transformer coupled to a load arrangement, the transformer being connected to an output of the amplifier and being configured to establish a magnetically coupled feedback loop from an output of the amplifier to an input of the amplifier wherein the transformer has a primary winding in series with the output of the amplifier and a secondary winding coupled to the input of the amplifier wherein the primary winding and the secondary winding are arranged such that a portion of a magnetic field generated by the primary winding couples to the secondary winding so as to establish the magnetically coupled feedback loop and wherein a loop gain of the magnetically coupled feedback loop is substantially independent of an impedance of a load included within the load arrangement and is defined at least in part by a coupling factor and turn-ratio of the transformer;
wherein a bias current, and not a supply voltage, provided to the amplifier circuit is adjusted based upon the envelope detection signal.