An RF front-end with an automatic gain control technique for a U/V band CMMB receiver

摘要

This paper presents a fully integrated RF front-end with an automatic gain control (AGC) scheme and a digitally controlled radio frequency varied gain amplifier (RFVGA) for a U/V band China Mobile Multimedia Broadcasting (CMMB) direct conversion receiver. The RFVGA provides a gain range of 50 dB with a 1.6 dB step. The adopted AGC strategy could improve immunity to adjacent channel signal, which is of importance for CMMB application. The front-end, composed of a low noise amplifier (LNA), an RFVGA, a mixer and AGC, achieves an input referred 3rd order intercept point (IIP3) of 4.9 dBm with the LNA in low gain mode and the RFVGA in medium gain mode, and a less than 4 dB double side band noise figure with both the LNA and the RFVGA in high gain mode. The proposed RF front-end is fabricated in a 0.35 μm SiGe BiCMOS technology and consumes 25.6 mA from a 3.0 V power supply.