How to generate voltage reference signal higher than 1.2V

[bhl777]

Hi All, when we use normal bandgap reference, we have around 1.12V reference signal, and can use a buffer and voltage divider to get the signal less than 1.12V. However, for example, we need 2V reference signal, how can I use this 1.12V output from bandgap circuit to generate it?Thank you!

 

[andre_luis]

You can shift ground reference to obtain desired voltage.


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[bhl777]

Hi andre_teprom, could you use a schematic to teach me about this idea? I don't quite follow it. Thank you!

You can shift ground reference to obtain desired voltage.


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[kam1787]

What is your V from the power supply?

 

[bhl777]

Hi kam1787, could you teach me the following two cases?

(1) If supply is 1.2V, what will the circuit look like? That means Vcc< the target signal we want.
(2) If supply is 2.5V, what will it look like? That is a normal case.

Thank you veyr much!

What is your V from the power supply?

 

[kam1787]

how tight is the tolerance on the Vref?

does it have to be temperature independent?

How much current does it have to supply?

 

[bhl777]

Actually I am asking a general question, not for a specific design. If we do not care about the current, and treat the reference as a ideal temperature insensitive value, how can we get 2V from 1.12V, both in 1.2V design and 2.5V design? Thank you very much!

how tight is the tolerance on the Vref?

does it have to be temperature independent?

How much current does it have to supply?

 

[xingkongwu]

1>you can combinate voltage of two Vbe and PTAT to get 2.24V
2>you can get a constant current of temp and then get voltage by using res

 

[bhl777]

Hi xingkongwu, regarding your answer "2>you can get a constant current of temp and then get voltage by using res",
How can we convert this reference signal to a reference current? Does that mean introducing an temperature insensitive OTA? Or there is any simpler way to do it? Thank you very much!

1>you can combinate voltage of two Vbe and PTAT to get 2.24V
2>you can get a constant current of temp and then get voltage by using res

 

[kam1787]

1>you can combinate voltage of two Vbe and PTAT to get 2.24V
2>you can get a constant current of temp and then get voltage by using res

How would you arrange 1>?

I do not understand 2>

I think the OP wants to know....................."how can we get 2V from 1.12V, both in 1.2V design and 2.5V design"

 

[xingkongwu]

hi bhl3302 , you can do it like this

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Hi xingkongwu, regarding your answer "2>you can get a constant current of temp and then get voltage by using res",
How can we convert this reference signal to a reference current? Does that mean introducing an temperature insensitive OTA? Or there is any simpler way to do it? Thank you very much!

hi ,if you have got a Vref ,you can get a reference current by using OPA and res

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hi ,it's difficult to get a Vref higher than power voltage unless using boost circuit . in 2.5v design ,you can get a current insensitive with temp through OPA and res .then get a voltage from 2 to 1.12v through res