simulation of bandgap circuit

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sys_eng

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I got a bandgap circuit for constant output of vref=550mV .

but i simulated , I don't get that, too much difference, I got 4.362 V output for vref and its not independent of supply voltage
what's wrong. It's nowhere near the ball park.



my actual circuit.



the current should be around 1.2uA
but my actual circuit is 100uA+, or near 200uA.



should I scale the transistor much smaller? I didnt' scale my transistor size in circuit so probably default to 100u.
 
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First thing I modified is the sizing of transistors to reduce the current, I have changed W=100u to 10u, on M21 but the current still remains strong at 192.9uA. I want to bring it down to 1.2uA. How do I do that?

 

Match M21 and M22. Mismatch M29 and M30 rather
than making them both 1 square but different W=L.
The 10K load on VB is a bad idea, jacks the diff amp
badly. There is not enough available drive or gain
for that loading.
 

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