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Why offset voltage of mos transistor is smaller than bipolar

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hr_rezaee

hr_rezaee

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hi
Why offset voltage of mos transistors is smaller than offset voltage of bipolar transistors?
please, answer and if you can introduce references.
regards
 

Re: Why offset voltage of mos transistor is smaller than bip

hr_rezaee said:
hi
Why offset voltage of mos transistors is smaller than offset voltage of bipolar transistors?
please, answer and if you can introduce references.
regards
Click to expand...
You can calculate, but shortly bipolars have exponential, and mos ()^2 characteristics (lower gm). This means that same ΔI mismatch of differential pair (for example caused by resistor mismatch) would produce smalled input voltage mismatch in the case of bipolars...
 

    hr_rezaee

    hr_rezaee

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The mismatch is depends on the circuit design and process matching. But not depends on MOS or bipolar.

Btw, ususally bipolar transistor have lower Vbe matching than MOS Vt
 

Re: Why offset voltage of mos transistor is smaller than bip

pixel said:
You can calculate, but shortly bipolars have exponential, and mos ()^2 characteristics (lower gm). This means that same ΔI mismatch of differential pair (for example caused by resistor mismatch) would produce smalled input voltage mismatch in the case of bipolars...
Click to expand...

hi
thanks
it is logical.
regards
 

Re: Why offset voltage of mos transistor is smaller than bip

But some text book says bip has little offset voltage ?
 

Re: Why offset voltage of mos transistor is smaller than bip

tandr said:
But some text book says bip has little offset voltage ?
Click to expand...
hi
it is true.
reards
 

bipolar are ALWAYS better matched than mosfet. probably 10x better (1mV vs 10mV) with careful layout. it's due to the fact that junction diffusions are easier to control than oxide characteristics.
 

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