指导教授林志明.ppt

An Ultra-Low-Power, TemperatureCompensated Voltage Reference Generator 指導教授:林志明 教授 學 生:劉彥均 Outline Circuit Description Supply Voltage Dynamic Temperature Compensation Line Sensitivity Experimental Results Conclusion Circuit Description Circuit Description A low temperature drift voltage reference is obtained by compensating the temperature dependence of the generated current with the temperature dependence of the NMOS threshold voltage. The particular configuration used allows us to suppress the effect of the temperature dependence of mobility. The proposed voltage reference was implemented in AMS 0.35 μm CMOS IC technology. Circuit Description(A)Current Generator Circuit(1) In order to reduce the channel modulation effect that causes a mismatch between the currents in the two branches, the channel lengths of the two transistors M5 and M6 are chosen large enough. Circuit Description(A)Current Generator Circuit(2) Transistors M1 and M2 are biased in the subthreshold region, while transistors M3 and M4 work in the saturation region. region. Such behavior is achieved through careful biasing: The gate-source voltage of M3 (M4) must be larger than the gate-source voltage of M1 (M2) Since the four transistors have the same drain current The W/L ratio of M1 (M2) has to be larger than that of M3 (M4). Circuit Description(A)Current Generator Circuit(3) The I-V characteristics of a MOS transistor that operates in the saturation and in the subthreshold region can be approximated by (1) and (2), respectively. Circuit Description(A)Current Generator Circuit(4) Assuming that the currents in the two branches of the current circuit generator are equal, the current becomes: Circuit Description(A)Current Generator Circuit(5) The effect of channel length modulation of M1 and M2 is negligible(subthreshold region, ). The channel length modulation effect of M3 and M4 is negligible since they are long-channel devices, and since their drain-sourc