A transmitter MMIC was designed for IMT2000 handset application using SiGe BiCMOS technology that is suitable for high-speed and high-frequency circuits. The transmitter MMIC composed of an up-conversion mixer(up-mixer) and a driver amplifier.
Two up-mixers were designed. One is a DSB(double sideband) mixer that has RF outputs of the desired sideband and the unwanted sideband(image band). But, the other is a SSB(single sideband) mixer that has only RF output of the desired sideband. The designed up-mixers are based on the Gilbert active topology. The simulation results of two up-mixers are similar. But, a SSB mixer has a image band suppression of more than 35 dB.
Driver amplifier was designed as variable gain amplifier(VGA) to control output power level.
The designed driver amplifier has a linear-in-dB gain characteristic, include compensation circuit for temperature and supply voltage variation of the gain. The simulation results of driver amplifier indicate the gain control range of more than 34dB, the gain of 25.9dB, the output IP3 of 27.5dBm, and 30mA current consumption from a 3V supply voltage.
