A Design Of Bandgap Reference Voltage On 65nm Technology And Optimization Of Low Power Dissipation And Low Temperature Coefficient For It

The function of bandgap reference voltage is to offer a reference voltage or current which is independent of supply voltage,process and temperature.It's widely used in phase locked loop(PLL),analog to digital/digital to analog converter(ADC/DAC),low dropout regulator(LDO)and other integrated circuits.With the rapid development of integrated circuits and the wide application of more portable electronic products in current days,the design of bandgap reference voltage not only need high precision,that is low temperature coefficient,high PSRR and so on,but also need the design for a lower power dissipation to be used for a long time.First of all,this paper introduces the overseas and domestic research status of bandgap reference voltage and explains the generating theory of the bandgap reference,then it analyses several bandgap reference structures with their advantages and disadvantages according to the design requirements in recent years.On the basis of the theory analysis,this paper designs a traditional bandgap reference structure,and it has good application.For instance,it is well used in FT-SerDes which is designed by our research group in this paper.This design takes the goals,the difficultly,the resource demands and so on factors comprehensively into account,and selects appropriate structure to design bias circuit,operational amplifier,low temperature coefficient module and so on.After the circuit design,I complete the layout design and have simulated this circuit under the 65 nm CMOS process.In this simulation,the value of the temperature coefficient is 53.7ppm/ ? during the FT-SerDes application temperature range from-55? to 125?,and the other value is about 46.8 ppm/? during the general civil use temperature range from-40? to 85?.In addition,the value of PSRR is-86 dB.So these performances of this design satisfy the application requirements of FT-SerDes system.Because the previous bandgap reference design in FT-SerDes is not suit for lower power dissipation application for big power dissipation(It's efficient value of current is 182uA),and higher precision circuits need lower temperature coefficient.We need improve the previous bandgap reference structure to not only introduce low power dissipation methods but also research lower temperature coefficient circuit structure.Because the main resource of power dissipation is from the proportional to absolute temperature(PTAT)circuit module and operational amplifier,and reducing the temperature coefficient is also related to the PTAT module.Improving the traditional proportional to absolute temperature circuit structure is very necessary.The new structure of the PTAT is composed of diode-connected and positive/reverse-biased MOS devices which work in subthreshold region.On the one hand,this structure reduces the power dissipation in a great extent,and on the other hand it has a better compensation to complementary to absolute temperature(CTAT)voltage than traditional structure.Besides that,the structure of bandgap reference uses operational amplifier which works in subthreshold and big resistors to decrease much power dissipation.Moreover,adding a sample and hold circuit structure reduces power further.After satisfying the low power dissipation and low temperature coefficient desires I add a positive feedback to this bandgap structure to increase the PSRR of the reference voltage.At last,this design is still simulated in 65 nm CMOS process,and we get the value of temperature coefficient is 15.5ppm/? which is better than last design.At the same time,the current dissipation of the design is 213.7nA which reduces almost 1000 times comparing to previous circuit.As for the PSRR,the value of PSRR is-65 dB and this structure also has a good rejection to supply's noise.In the end,comparing this two structure and their simulating results presents optimizing goals to make the results better.