New CMOS Voltage Reference Based on Different VTH Value
Qingchun Wang · Modern Electronics Technique · 2011
The traditional reference circuits mainly employ the bandgap reference scheme,which obtains a zero temperature coefficient based on forward voltage with negative temperature coefficient of diode p-n junction and ΔVBE voltage with positive temperature coefficient.To overcome the compatibility defect of BJT and CMOS technology,a new CMOS reference based on different VTH values was designed by using the temperature coefficient of NMOS and PMOS threshold voltages(VTHN and VTHP) which are same in direction but different in magnitude.There is no amplifier and BJT in the circuit,whose structure is simple,and suitable for standard CMOS process integration.The circuit passed the Hspice validation.Its output reference voltage is 1.22 V,temperature coefficient is merely 30 ppm/℃ at ―40~+85 ℃ and supply voltage regulation factoris 1.996 mV/V when supply voltages is 2.6~5.5 V at 25 ℃.