High Harmonic-rejection Matching Filters for Quad-band Power Amplifiers

摘要

In this article, matching filters for GSM amplifiers capable of providing large harmonic rejection are demonstrated using M/A-COM's high Q GaAs MMIC technology. The matching filters are designed for the output of the quad-band (GSM 850/900/1800/1900 MHz) wireless handset amplifier module. Two sets of high harmonic-rejection matching filter circuits are designed and fabricated, one each for the GSM 850/900 MHz and GSM 1800/1900 MHz bands, respectively. For the second harmonic, the amplifier with the matching filter in the plastic-packaged module gave a rejection better than -63 dBc for the GSM 850/900 MHz band at the fundamental output power of 33 dBm and better than -63 dBc for the DCS 1800/1900 MHz band at the output power of 31 dBm. The higher harmonics had a better than -62 dBc rejection. The in-band insertion loss is measured as low as 1.2 dB in the 800/900 MHz band. To the best of the author's knowledge, this is the highest harmonic rejection achieved through a low pass matching filter for GSM handset amplifiers based on a MMIC process.