When 1 mega Ohm resistors are used?

[angelspikes]

When and "for what purpose"/why are 1 mega ohm (1 MΩ) resistors used in filters, such as high pass filters? Is it with regards to electrostatic discharge or impedance matching?

What difference does it make, if I only use a 10 K ohm resistor, when the high pass frequency will be the same (by changing the value of the capacitor)?

 

[analogdesign]

They are used, for example, as a feedback device in charge-sensitive amplifiers. If you use a 10 k Ohm resistor you can have more current that a 1 M Ohm resistor. Sometimes that matters.