A front-end module for CDMA based on zero shrinkage of LTCC

A compact RF front-end module for CDMA application is presented employing low temperature co-fired ceramic (LTCC) technology. It consists of an InGaP/GaAs HBT MMIC PA, a SAW duplexer, a Tx SAW filter, a power detector on top of the LTCC substrate, and a quarter-wave-length transmission line in the substrate. Some experimental data of constrained sintering technology is introduced in order to reduce the dimensional uncertainty of the LTCC and provide high-density component configuration. The total size of the module is 5 mm times 5.5 mm times 1.2 mm. Measured results of the proposed module show an output power of 25 (I Bin and a gain of 25.2-dB in the Tx band with a 3.4 V supply. The adjacent-channel power ratios (ACPRs) at 885-kHz and 1.98-MHz offset are -42.4 dBc/30 kHz and -54.9 dBc/30 kHz, respectively. Measured second- and third-harmonics are -49 dBc and -53 dBc, respectively, at a 25-dBm output power.