Research Of The Variable Gain Amplifier For Multi-Mode Multi-Band Wireless Receiver

The development of the wireless communication is now entering a brand new era, and the combination technology between different communication standards is becoming more and more mature. Nowadays the product of the wireless communication terminal based on Multi-Mode Multi-Band is coming out one after another.In this dissertation, after the study of a great many papers on the wireless receivers and the variable gain amplifiers(VGA), a chip of VGA applied in the multi-mode, multi-band wireless receiver is designed and fabricated in CMOS 0.13μm process. The chip can support these four standards:GSM (the second generation mobile communication), WLAN (wireless local area network), TD-SCDMA (the third generation mobile communication), and RFID (key technology of the internet of things). The main achievements are listed as follows:1. Started from the familiar structure of wireless receivers, an optimal structure of Multi-Mode Multi-Band receiver is proposed. Then after a detailed analysis of the advantages and disadvantages of the Zero-IF Receiver, the solution to those problems is given. At last, the design specifications of the VGA for these four communication standarts are given through a careful calculation.2. A fully differential VGA with low voltage and low power is proposed. The voltage for this VGA is only 1.5V. After the circuits design, the post-simulation results of the VGA are shown as follows:the total power is below 3.8mW, and the gain range is from ldB to 59dB with 2dB steps while the 3dB-bandwidth is keeping above 10MHz, the noise figure(NF) is 19.6dB, the input third-order intercept point(IP3) is about 4dBm and the group delay (GD) is below 25ns.3. A low voltage bandgap which can provide 0.75V reference voltage and 10μA reference current is designed. The post-simulation results of the Bandgap are shown as follows:the temperature coefficient of the reference voltage is 7ppm/℃, the power supply rejection ratio(PSRR) is above 70dB, and the Bandgap can drive 25pF load.4. After building a test bench, the chip of VGA is tested. The preliminary measurement results are as follows:the 3dB-bandwidth is above 10MHz during all the gain range, the NF is 22.6dB, the IIP3 is-1.5dBm and the GD is about 60ns. The existing measurement results give a further verification of the correctness of the design theory, and show us the great guiding significance for the future work.This dissertation's work is supported by project "Key IP cores design for the embedded multi-mode multi-band transceiver" under the state key item of "core electronic devices, high-end general chips and basic software product" (Project number:2009ZX01034-002-002-001-02).