US 11,671,061 B2
Load-line switching for push-pull power amplifiers
Netsanet Gebeyehu, San Jose, CA (US); Tianzuo Xi, Milpitas, CA (US); Sukchan Kang, San Jose, CA (US); and Nan Ni, Milpitas, CA (US)
Assigned to SKYWORKS SOLUTIONS, INC., Irvine, CA (US)
Filed by SKYWORKS SOLUTIONS, INC., Irvine, CA (US)
Filed on Sep. 25, 2019, as Appl. No. 16/582,143.
Claims priority of provisional application 62/736,540, filed on Sep. 26, 2018.
Prior Publication US 2020/0099348 A1, Mar. 26, 2020
Int. Cl. H03F 1/56 (2006.01); H03F 3/26 (2006.01); H04B 1/401 (2015.01)
CPC H03F 1/56 (2013.01) [H03F 3/26 (2013.01); H04B 1/401 (2013.01); H03F 2200/387 (2013.01); H03F 2200/451 (2013.01); H03F 2200/48 (2013.01); H03F 2200/534 (2013.01); H03F 2200/537 (2013.01); H03F 2200/541 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A push-pull power amplifier system having an input, an output, and a variable load-line impedance comprising:
an input amplifier coupled to the input of the push-pull power amplifier system to receive an unbalanced radio frequency (RF) input signal and provide an unbalanced amplified RF signal at an output of the input amplifier;
an input transformer having a primary winding coupled to the output of the input amplifier and having a secondary winding to provide a pair of balanced RF signals based on the unbalanced amplified RF signal;
a pair of complementary amplifiers to receive a respective balanced RF signal of the pair of balanced RF signals and provide a pair of amplified balanced RF signals;
an output transformer having a primary winding to receive a respective amplified balanced RF signal of the pair of amplified balanced RF signals and a secondary winding to provide an unbalanced amplified RF output signal on a load-line coupled to the output of the push-pull power amplifier system;
a switchable shunt capacitance switchably connected between the load-line and a reference potential; and
a switch configured to selectively connect the switchable shunt capacitance to the reference potential and disconnect the switchable shunt capacitance from the reference potential to vary an impedance of the load-line to match an impedance at the primary winding of the output transformer.