Highly linear variable gain amplifiers with programmable temperature compensation for CDMA wireless applications

Highly linear and low power variable gain amplifiers (VGA´s) with digitally programmable temperature compensation has been developed using a 15 GHz 0.5 μm BiCMOS process for CDMA mobile phones. Receive-VGA (RxVGA) shows 135-dB gain control range, 4.95 dB noise figure at a maximum gain, and -1.35 dBm IIP3 at a minimum gain with current consumption of 8 mA. Transmit-VGA (TxVGA) shows an output P_{1 dB} of 4.7 dBm with current consumption varying from 6 mA to 24 mA according to its gain. The temperature compensation has been achieved within ±0.2 dB variation over the entire temperature and gain range. In addition, for easy application of the VGA´s for mobile handsets, a simple method is presented for a programmable temperature compensation. A two-bit digital input is used to modify the temperature compensation characteristics by 1.5 dB/1110°C per a step