Pre-distortion linearizer module using InGaP-HBT based MMIC for LDMOS high-power amplifier

We have developed a miniature and simple pre-distortion linearizer module for Wide-band code division multiple access (W-CDMA) base station power amplifier. Si-LDMOS FETs are widely used as final stage for this application. In general, the same Si-LDMOS device has also been used as pre-distorter to cancel distortion made at the final stage. However, the circuits become complex and larger in size. We took a different approach by using InGaP HBT based MMIC (monolithic-microwave integrated circuit) as pre-distorter and achieved a simple, compact pre-distorter with ease of use. By using this pre-distortion linearizer module, we have demonstrated 15 dB reduction of adjacent channel leakage power ratio (ACLR) on 800 MHz band power amplifier (PA) and over 6 dB reduction on 2.1 GHz band PA. ACLR<-55 dBc@42 dBm was achieved and ACLR was improved for a broad power range in both PAs.