Bandgap refernce design

[sherlock176]

Hello all!

I am using gpdk180nm CMOS lib for designing BGR circuit. I have designed the circuit using current mirror. But to improve this circuit I am using op-amp. I need to know what type of op-amp should I use for getting 1.12 V const ref voltage for temp range -40 to 125?

What should be the gain, BW, PSRR, CMRR of the oPamp? Should i use PMOS inputs or NMOS input opamp. Please help me designing the opamp for this library or send me the design screenshot.

Please guide me!

 

[KlausST]

Hi,

All this depends on your circuit. You should give at least your example circuit.
* Supply voltage?
* output current? source only? or sink too?

gain: How much gain do you need? What is the input voltage? I estimate it should be a unity gain buffer, am I right?
BW: For me a reference voltage could be considered to be DC. Now it depends on the load current frequency, specified load capacitance .. and how much output voltage error is allowed?
PSRR: What powersupply fluctuation do you expect?.. and how much output voltage error is allowed?
CMRR: Does the common mode voltage fluctuate? I don´t think so.
PMOS/NMOS: I´m no expert, but i think this depends on common mode input voltage.

Klaus

 

[sherlock176]

Supply voltage i am taking is 1.8V and ICMR for nmos inputs is 0.8V to 1.6V and for PMOS inputs 0.1V to 0.9V

 

[KlausST]

Hi,

still don´t know what your input voltage is..

and for PMOS inputs 0.1V to 0.9V

I assume it is 1.12V, then it is not in the range for PMOS. So use NMOS.

Klaus