Generating the bias voltage of an op-amp

[jsaenz]

Bandgap Reference

it's also possible use an voltage reference with transistors CMOS in weak inversion...the output voltage can be controlled by resistors too.

 

[northeast1]

Re: Bandgap Reference

So I am trying generate the bias voltage of an op-amp. So far the only circuit I know that can be used to generate the bias voltage is bandgap reference. But bandgap reference can only generate a voltage that is around 1.4V. I need a bias voltage that is higher than 1.4V...What circuit should I use?

add a buffer to generate 1.4v

 

[rillyxue]

Re: Bandgap Reference

use ldo is not a good way, you can use a bandgap to generate a bandgap current source , and then use this current source to generate a bias voltgae.

 

[chibijia]

Bandgap Reference

how to simulation its psrr

 

[ppcicy]

Bandgap Reference

you can use a close loop buffer .

 

[jsaenz]

Re: Bandgap Reference

About the way to simulate the PSRR on the Bandgap , I commonly insert a sinusodal voltage source on the Vdd or GND pin (depends on PSSR+ or PSSR-), and then i measure with a .ac statement at the Vref pin the gain of this source. Normally, the worst case of this measure is when the circuitś gain is 1, therefore a unitary gain loop must be to add.

 

[engronger]

Re: Bandgap Reference

i think you can still use bandgap,
the bandgap that base on current independent can get a voltage high than 1.2V
by the way, LDO is not a good idea, LDO is designed to drive large current not here.

So I am trying generate the bias voltage of an op-amp. So far the only circuit I know that can be used to generate the bias voltage is bandgap reference. But bandgap reference can only generate a voltage that is around 1.4V. I need a bias voltage that is higher than 1.4V...What circuit should I use?

Added after 1 minutes:

you can do it as a AC sweep.
the difference only is that the input is changed to VDD or GND.

how to simulation its psrr