Envelope tracking technique for multimode PA operation

We will present the realization of an envelope tracking (ET) transmitter supporting multi-standard applications. The AB biased harmonic-tuned class-F (class-AB/F) power amplifier with the novel envelope shaping method linearly amplifies the input signal with high efficiency. The hybrid switching supply modulator with programmable hysteretic comparator enables the multi-mode operation, whatever the envelope signal characteristics such as the peak-to-average power ratio (PAPR) and the bandwidth are. The designed ET transmitter is fabricated with CMOS 0.13 μm technology and InGaP/GaAs 2 μm HBT process for the supply modulator and the power amplifier, respectively. For IEEE 802.16e m-WiMax signal, it shows a power-added efficiency (PAE), an average output power (Pout), and a gain of 34.3%, 23.9 dBm, 27.9 dB, respectively. At those power levels, without any pre-distortion techniques, it satisfies the overall spectrum emission mask specifications. The relative constellation error (RCE) and the error vector magnitude (EVM) for m-WiMax signal are -30.5 dB and 2.98%, respectively. For a WCDMA signal, it presents a PAE, a Pout, and a gain of 46%, 29 dBm, and 27.8 dB, respectively. For EDGE signal, it delivers a PAE of 45.3% at a Pout of 27.8 dBm with a gain of 29.4 dB. This is the first demonstration of the truly multimode operation of a PA.