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Generating the bias voltage of an op-amp

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Bandgap Reference

how can he use 1.4v for reference to generator higher reference voltage.
 

Re: Bandgap Reference

u can refer the below paper
 

Re: Bandgap Reference

What you could do is to use 1.4 V as a supply to a Nakagome charge-pump, and feed the same 1.4 V as input to the charge-pump. For instance, in the second figure, in the link
**broken link removed**
Vout is twice the supply. What say?
 

Re: Bandgap Reference

Raghav's reply seems helpful. In fact, Nakagome charge pump is used to boost voltages in DRAM cells too. So, it should raise the band-gap voltage to any required value.
 

Re: Bandgap Reference

qutang said:
why u are using a bandgap bias the opamp?
Click to expand...
i have the same doubt,especially, voltage bias
 

Re: Bandgap Reference

lijianheng said:
Try this one
Click to expand...

for the figure "bg.jpg" how to choose the characteristics of Opamp used ? or how to test the opamp to be used for this purpose ?
 

Re: Bandgap Reference

hi
i m designing second order curvature corrected band gap reference circuit will anybody help me how to design that
my moses are in cutoff
i m sending one paper on this pz help me


regards
aadi
 

Re: Bandgap Reference

to bias a opam, a Iref from BG or orther reference is enough. When you need Vref, just dump Iref to a diode-connected MOS.
 

Bandgap Reference

Hi
I had designed a bandgap reference... The circuit is doing absolutely fine in simulations... even the post-layouts are also fine. But the silicon shows oscillations at the output and the RMS value is also not 1.2v its way away to 1.9 volts...
any clue to debug.
thanx
 

Bandgap Reference

to ashish_chauhan
maybe you can add a cap. at vdd and output.
 

Bandgap Reference

1.4v?
 

Bandgap Reference

using a charge pump would be the easiest but you would have to take care of the ripple by using a filter
 

Re: Bandgap Reference

qutang said:
to ashish_chauhan
maybe you can add a cap. at vdd and output.
Click to expand...

I tried that but how much can you cut down through that... the ripples are full fledged oscillations of 1v peak to peak!!!
 

Re: Bandgap Reference

why not you use the resistor to divide the supply if you don't need a precise voltage.
but if you want to get a precise voltage, you can use a negtive feedback with a opamp.

But usually we don't need a very precise voltage bias. because it is differential pair as the input.
 

Bandgap Reference

I think the problem is the accuracy of the voltage bias. Do you really need the 0.1% accuracy ? If that ,you can use a kind of bandgap which can generate all values of voltage, in theory, not boter to use LDO,that is pretty a big wast.
 

Bandgap Reference

you can use a opamp as a voltage follower, and a DAC which tuning up the 1.4V and VDD
 

Re: Bandgap Reference

If u got a supply >2V & a bias current then couple of diode connected mosfet in series is good enough to generate 1.4V .I am assuming bias current is available and not a good idea to build regulator to bias .
 

Bandgap Reference

could somebody tell me what the beta-multiplier is ?
LDO and charge pump is not a well way
OPA add Resister booster the voltage!
 

Bandgap Reference

There are lots of bandap configuration which can generate any voltage value.
 

Bandgap Reference

i f only need a bias voltage ,why ont choose constant gm? u can find in razavi's book.
 

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