An LTCC power amplifier module integrated with a SAW duplexer

A compact power amplifier module (PAM) integrated with a SAW duplexer utilizing low temperature co-fired ceramic (LTCC) technology is presented for the IS-95 CDMA frequency plan scheme. The proposed single module is composed of an InGaP/GaAs HBT MMIC PA and a SAW duplexer on top of the LTCC substrate, and a quarter-wavelength stripline, RF chokes, an output matching circuit in the substrate. Compared to conventional LTCC modules, this proposed module has adopted heterogeneous structure, which is composed of two different ceramic sheets with er= 7.4 and 17.5. The high K material reduces the capacitor areas efficiently keeping high Q value of capacitors, and the low K material allows the stripline to reduce signal delay time. The total size of the LTCC substrate is 6.0 mm × 6.0 mm × 0.7 mm. Measured results of the proposed module show an output power of 25 dBm and a gain of 25.1 dB at a center frequency of 836.5 MHz in the Tx band with a 3.4-V supply. Measured secondand third-harmonics are -58 dBc and -50 dBc, respectively, at a 25-dBm output power. The adjacent-channel power ratios (ACPRs) at 885-kHz and 1.98-MHz offset are -51 dBc/30kHz and -57 dBc/30kHz, respectively.