Quadrature Power Amplifier for RF applications

new power amplifier (PA) architecture is proposed as a more power efficient way to amplify modulated signals at radio-frequencies (RF) compared to conventional polar power amplifiers. Polar PA's, using the Envelope Elimination and Restoration (EER) linearizing technique for high efficiency switch mode amplifiers provide amplification for modulated signals at RF with high efficiency and linearity. However, such systems require high alignment between phase and amplitude signal paths and the bandwidth of the amplitude path needs to be three to four times the RF-bandwidth. The latter directly translates to high power consumption. Instead of decomposing the quadrature signals to a phase and amplitude signal set, suggested is that the quadrature signals are to be directly amplified using a quadrature power amplifier. The lack of a separate phase and amplitude signal path avoids the linearity and bandwidth requirements, thus reducing power consumption. A possible quadrature PA architecture is presented. This architecture consists of two supply modulated switch mode amplifiers placed in a bridge and is capable of handling negative voltages, modulation and power combining at RF. Furthermore, a driver architecture is presented to properly drive the quadrature PA. Simulations results of the quadrature PA using 90nm CMOS models show a functional quadrature PA model with a power added efficiency of 30% at 6.4dBm output power driven at 2.4GHz and a maximum input power at 10MHz and 25% at 5.1dBm output power at 50MHz.