Hybrid ET Supply Modulator IC with an Adaptive Quiescent Current Controller for Its Linear Amplifier

This paper presents a hybrid ET SM IC based on a Class-AB LA with supply voltage and temperature insensitive quiescent current for dual-mode operation. For ET mode, supply voltage of the LA can be modulated using a dc-dc converter according to the average power to improve efficiency of the SM. An adaptive quiescent current controller for the LA is proposed to maintain its quiescent current for large variation of the voltage and temperature. The supply voltage to the LA can be controlled in wider range using the adaptive quiescent current controller for more efficiency improvement. The proposed SM and PA ICs were implemented using CMOS processes for the 0.9 GHz band. Using an uplink LTE signal, a PAE of 38.4% at an output power of 24.0 dBm was obtained, while a PAE of 24.6% was achieved at 6 dB output power back-off.