The Research And Design Of Voltage Reference Source Of Subthreshold CMOS

Reference source including reference voltage source and reference current source,reference source module widely used in simulation and hybrid integrated circuit, such as A/D,D/A converter, etc, The performance of the reference source module directly affect systemperformance. In this paper, we designed reference voltage source consisting of subthresholdMOSFETs. On the basis of the reference circuit voltage mode and current-mode referencecircuit, we improved the circuit focusing on two performance indicators of circuit, thetemperature coefficient and the power supply rejection ratio of output voltage.For the designing of the current mode reference voltage source, In this paper, wecompared the performance of common temperature compensation strategy, combined withthe characteristics of the current mode circuit select piecewise temperature compensationstrategy. We discussed the design principle and circuit implementation of piecewisetemperature compensation circuit of the paper. micro power operation amplifier is used toimprove power supply rejection ratio of output reference voltage by improving power supplyrejection ratio of PTAT current source and don’t cause excessive power consumption. For thedesigning of the voltage mode reference voltage source, a voltage with positive TC isgenerated by a source-coupling pairs with subthreshold and adds the gate-source voltage withsubthreshold CMOS to obtain a output voltage with a zero TC, it discussed the designprinciple of temperature compensation circuit. To improve power supply rejection ratio ofoutput reference voltage，the current source subcircuit is a modified β multiplier self-biasingcircuit with micro power operation amplifier. Resistor was instead of the MOSFET workingin the linear region to reduce the layout area.Finally, the circuits were simulated based on Chat0.18um standard CMOS process bySpectre of Cadence. The simulation results demonstrated that the minimum working voltageof two circuits are1.1V, the output voltage are364.45mV and797.9mV, the temperaturecoefficient respectively in the temperature range-40C～140oCand-40C～125oC are10ppm/°C and12ppm/°C, the power supply rejection ratio respectively for84dB and80dB.