CMOS compatible medium voltage LDMOS transistors for wireless applications up to 5.8 GHz

The design and characterization of CMOS compatible medium voltage LDMOS transistors are presented. Devices of different sizes were fabricated in a 0.25 μm BiCMOS technology and were characterized in the most important wireless telecommunication bands up to 5.8 GHz using a load/source pull measurement setup. Alternative layouts with regards to device geometry and stabilizing networks were investigated. Some of the transistors were equipped with on-chip stability networks to guarantee safe operation over the whole frequency band. This is shown to be established without substantial performance degradation. The medium size 1.8 mm device shows state-of-the-art performance over bandwidth with peak drain efficiencies of 51%, 44% at 2.66 GHz, 5.8 GHz providing a saturated output power of 30.1 dBm, 29.7 dBm. The linearity performance at all bands was investigated by determining the adjacent channel power ratio for a WCDMA test signal. The excellent RF performance achieved is verified in a real design by means of a hybrid class-AB power amplifier operating at 5.8 GHz.