Balanced power amplifier with a bypass structure

Abstract

A balanced power amplifier circuit arrangement comprises a driver amplifier stage ( ) adapted to receive and amplify a signal. The amplified signal is input to a first coupler ( ). The first coupler ( ) produces an in-phase signal and an out-of-phase quadrature signal. A first power amplifier ( ) receives and amplifies the in-phase signal. A second power amplifier ( ) receives and amplifies the out-of-phase signal. A first switch ( ) alternately connects an isolated port of the first coupler to ground ( ) or a bypass path ( ). A second coupler ( ) receives and combines the amplified in-phase signal and the amplified out-of-phase signal to produce a combined signal. A second switch ( ) alternately connects an isolated port of the second coupler ( ) to either ground ( ) or the bypass path ( ). When the power amplifiers ( ) are powered down, the first coupler ( ) splits the RF-signal into an in-phase signal and an out-of-phase signal. The power amplifiers ( ) appear as reflective impedances to the signal when they are powered down. Each signal reflects off the first and second power amplifiers ( ), respectively. The first coupler ( ) combines the reflected signals and routes the combined signal through the bypass path ( ) to the second coupler ( ). The second coupler ( ) splits the signal into an in-phase and out-of-phase signal and routes each to the power amplifiers ( ). The power amplifiers ( ) reflect each signal back to the second coupler ( ). The second coupler ( ) combines the signals and routes the combined signal to the RF-output port. The circuit arrangement enables the integration of the balanced amplifier and first and second couplers ( ) into a single power amplifier package to provide low power bypassing without the need of an external circulator component.