A Question about an Op Amp

[isaacnewton]

The attached picture is the simplified equivalent of TLC274 op amp.
**broken link removed**

Can somebody explain why they put R1 and R2 at the input (the Gates of P1 and P2)? Thx.

 

[sunking]

for ESD protected

 

[isaacnewton]

Could you please give some more explanation? How can resistors be used for ESD protection? Thank you.

for ESD protected

 

[tamerakshar]

well, since its connected to the transistor gates ; i bet its a current limiting resistors.

 

[the_risk_master]

Yeah, agreed to Tamirakshar,

It is also to limit the sharp transients that we unknowingly existed in out environment.

Chiao

 

[beckchm]

esd

but let gate do not float

 

[vlsiattitude]

its to limit the esd current that passes through reversed biased diodes.

 

[Miguel Gaspar]

Well, no matter how well designed the transistors are, they are always different
and the resistors R1 and R2 are used to activate the transistors. If you put the same source to both inputs only one transistor will activate. But with the resistances both will be activated.

 

[omsi]

the resistors at the inputs of transistors are kept for two functions.
1. to avoid floating gate when the inputs are left open.
2.to protect gate from any spikes in transient level.

 

[jiaming_lee]

if the opa used in feedback mode, with proper set resistance of R1 and R2, which are compared to output resistor, R1 and R2 can help balance the input and output resistance