Re: Regarding op-amp configs
ashugtiwari,
Lower resistance values provide a circuit that is less susceptible to capacitively coupled noise. Also, high values of resistance result in larger errors due to input bias current. But, if you connect the non inverting input to common through a resistor that is equal to the resistance that the inverting input "sees", then the bias current error is eliminated.
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The resistor, along with the input capacitor, forms a high pass filter, which attenuates input frequencies below a value determined by the capacitor and resistor values, The frequency at which the attenuation is 3db is fc = 1/(2*pi*R*C) Hz. The attenuation increases at a rate equal to 6db/octave, or 20db/decade.
Regards,
Kral