sunking said:you must have a trimming circuit
please can anyone tell ?Chethan said:what is this trimming circuit??
ramy_maia said:please can anyone tell ?Chethan said:what is this trimming circuit??
tekno1 said:Now trimming circuit: Because there will be variations process to process and also simulation is not %100 fits tp reality there normaly a provision as trimming of resistors so that if a very precise ref voltage is needed these trims are used.
Since trimming incurs extra test costs and chip area, implementation of it needs an optimization i.e. how many bits of trim is good enough and overal trimming strategy to cover as much trimming range needed with as small area.
ramy_maia said:please can anyone tell ?Chethan said:what is this trimming circuit??
tekno1,
Do you have any idea about how accurate a CMOS bandgap can really achieve?
I have designed tens of Bandgap circuits for different processes. But the testing result is not cheerful. By trimming, I can control the output voltage in ±20mV. It usually met the customer's requirment. But I think it's not accurate enough and want to find a way to improve it.
just to insure that i correctly understood you
you mean the trimmer circuit is a combination of resistors that i control them by a certain digital word to give me the required equivalent resistance,which lets the circuit operates after manufacturing nearly as the simulated values
am i right?
I have a question about trimming circuit.
Is the trimming circuit a kind of automatic feedback circuit that can sense output error and tune the reference circuit by itself? Or just some bits to control resistance ratio, but you have to switch on/off manully(I mean trimming chip by chip)
Thanks,
Design some switch circuit to change resistance to correct bandgap out voltage.
But it will change circuit's temp. curve.
johnq_hu said:tekno1,
Do you have any idea about how accurate a CMOS bandgap can really achieve?
I have designed tens of Bandgap circuits for different processes. But the testing result is not cheerful. By trimming, I can control the output voltage in ±20mV. It usually met the customer's requirment. But I think it's not accurate enough and want to find a way to improve it.
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