Patent ID: 8643433

Claim:
An apparatus for amplifying a radio frequency (RF) signal for transmission, comprising: a first power amplifier configured to amplify the RF signal to provide a first amplified RF signal; a second power amplifier configured to amplify the first amplified RF signal to provide a second amplified RF signal to an input of a transducer; an input matching network coupled between the first power amplifier and the second power amplifier and configured to match an output impedance of the first power amplifier to an input impedance of the second power amplifier; a quarter wavelength transmission line comprising a first end and a second end, the quarter wavelength transmission line configured to receive the first amplified RF signal at the first end and couple the first amplified RF signal to the input of the transducer at the second end; an output matching network coupled between the first power amplifier and the quarter wavelength transmission line and configured to match the output impedance of the first power amplifier to an input impedance of the transducer; and a first switch configured to couple the first amplified RF signal to the second power amplifier or to the first end of the quarter wavelength transmission line.