Multiplying D/A Converter Based On Quasi-Floating Gate Transistors

The measurement of the motor-shaft angle or speed is very important in close-loop control systems, so we need to measure the angle position accurately. Resolver-to-Digital Converter offers a widely used solution, its core device: Multiplying D/A converter must operate with high speed and accuracy. According to Resolver-to-Digital Converter's characteristic, a Multiplying D/A converter based on Quasi-Floating Gate Technique is proposed.In this paper, I design a Multiplying D/A Converter with 12 bits resolution:first, introduce the mathematical model of the RDC; Next, introduce quasi floating gate technique and structure of MDAC based on QFG. In sub circuit design, gain- boosted fully differential operational amplifier is used as the main OPA. A special output stage is designed to drive a very large load capacitor. The whole system will do behavior simulation by Spectre.The proposed MDAC uses UMC 0.18μm RF CMOS process. The input voltage is-0.45V～0.45V and the power supply is 1.8V.According to simulation, the system can achieve 12 bits resolution.