| The Variable Gain Amplifier(VGA)plays critical roles in order to maximize the dynamic range of the overall system in many applications for mixture signal VLSI, such as telecommunications applications, medical equipments, hearing aids, disk drivers and so on. With the rapid development of telecommunication, the highly improved performance of VGA embedded in receiver typically operated at small signal radio frequency is required, for examples, wide dynamic range, high linearity, low power consumption, and less occupied chip area. However, it is not easy to achieve this kind of high performance VGA with CMOS technology currently. So it becomes a challenge of analog circuit design.Based on the operational principle, the background of applications and development of the VGA, a CMOS VGA have been designed using a new exponential approximation approach with SMIC 0.18um CMOS technology according to the requirements of the engineering project. The simulation results show that good performance has obtained by presented design and the main parameters fit the specifications well, such as low power consumption, wider dynamic range, higher linearity, less gain error, and less occupied chip area. These results are relatively satisfactory compared to the conventional VGA design. This provides a very good reference for the current VGA design in wireless receiver. |
