A 3.2-V operation single-chip dual-band AlGaAs/GaAs HBT MMIC poweramplifier with active feedback circuit technique

摘要

This paper describes the design and experimental results for an3.2-V operation single-chip AlGaAs/GaAs heterojunction bipolarntransistor (HBT) monolithic microwave integrated circuit (IMMIC) powernamplifier for GSM900 and DCS1800 dual-band applications. The followingntwo new circuit techniques are proposed for implementing the powernamplifier. One is an on-chip HBT bias switch which in turn switches thenamplifier between 900 and 1800 MHz. The proposed switch configurationnallows the switch using a high turn-on voltage of 1.3 V of AlGaAs/GaAsnHBT's to operate with a 3-V low supply voltage, because the switchncircuitry needs no stacked configuration. The other is an activenfeedback circuit (AFB) to prevent permanent failure of HBT's in thenoutput power stage even under severe conditions of oversupply voltagenand strongly mismatching load. Experimental results revealed that thenproposed feedback circuit, which works as a voltage limiter, can protectnthe output stage HBT's from an excessive collector voltage swing evennwhen the amplifier is operated under a condition of a 5-V oversupplynvoltage and a 10:1 voltage standing-wave ratio (VSWR) mismatching load.nUnder a normal condition of 3.2 V and a 50-Ω matching load, the ICnis capable of delivering an output power of 34.5 dBm and a power-addednefficiency (PaE) of 52% in a GSM900 mode, and a 32-dBm output power andna 32% PAE in a DCS1800 mode