Re: Need high mega ohm of resistor , please help me , thank
amazonite,
Depending on your amplifier application, this might help. If the resistor is used as the input resistor or feedback resistor in an inverting amplifier, consider using a "Tee" network. Let R1, R2 be the series resistors, R3 the shunt resistor in the "Tee". The equivalent resistance is given by the equation
~ Req = R1 + R2 + R1R2/R3
By setting R3<<R1, R2, you can get a high value equivalent resistance without using high value resistors. The equation works for any application where both ends of the "Tee" are at ground or virtual ground. It does not work for a non-inverting OP Amp amplifier application.
~
One caveat; High humidity, as well as contaminants, can drastically affect the resistance value of a resistor with this high value of resistance.
Regards,
Kral