What is mismatch?, and what is tolerance?

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sina25

Joined: 12 Sep 2005
Posts: 33

27 Mar 2006 0:48 what is mismatch

What is mismatch?, What is tolerance?
what is the difference between mismatch and tolerance?

thanks

MSSN

Joined: 08 Mar 2006
Posts: 232
Helped: 26

27 Mar 2006 1:15 what is mismatch

An example of mismatch is when u r designing a differential amplifier u assume that both sides are perfectly matched,i.e. transistors have the same c/cs and resistors have exactly the same values but in reality when this amplifier is fabricated there is mismatch between the two transistors and the 2 resistors doesn't have the same value so u have to take care in ur design that in real word u can't get identical transistors or resistors even if they r on the same chip.

tolerance is the deviation of any parameter from its nominal value
for example u get a 100 ohm resistance with 1% tolerance that means that the value of the resistance may be anything from 99 to 101 ohm

Miguel Gaspar

Joined: 06 Mar 2006
Posts: 391
Helped: 36
Location: Culiacán, Sinaloa, Mexico

27 Mar 2006 2:22 resistor mismatch tolerance

I'm agree with MSSN Mismatch is relative of one device with another when they are supposed to be equal.

However for a tolerance it refears to the frabrication process that result in a nominal value an a range betwen this value could be. It is not refered to another device.

sina25

Joined: 12 Sep 2005
Posts: 33

27 Mar 2006 3:35 Re: What is mismatch?, and what is tolerance?

Is the difference between the tolerance values of two devices (resistors) in the same chip THE MISMATCH?

(Tolerance of R1) - (Tolerance of R2) = Mismatch between R1 y R2

thanks

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MSSN

Joined: 08 Mar 2006
Posts: 232
Helped: 26

27 Mar 2006 8:48 Re: What is mismatch?, and what is tolerance?

No the difference between the tolerance values of two devices (resistors) in the same chip is not the mismatch simply because if u have two resistors ,both have the same tolerance that doesn't mean that both have the same value
for example:if u have 2 100 ohm resistance with 1% tolerance that means that the value of each resistance may be anything from 99 to 101 ohm that means that one of them can be 99 ohm while the other is 101 ohm leading to mismatch of 2 ohm

sina25

Joined: 12 Sep 2005
Posts: 33

27 Mar 2006 12:38 Re: What is mismatch?, and what is tolerance?

thanks MSSN and Miguel Gaspar. I already understand ........

do you have papers, books or some document, where i can get the information that we discussed?,
i need bibliographic references of this information............
please upload them

thanks in advance