bachevelle52
Active member
- Joined
- May 23, 2009
- Messages
- 43
Preface: I'm an idiot.
How on earth do you calculate in/out impedance? If there are caps in the signal path at the input of a micamp (DC blocking) and i'm sure i've read that the impedance of a cap is dependant on frequency, is a stated input impedance referenced at a certain frequency?
....and, per the datasheet p.3 of the ina217, the input impedance is 60M||2pF. (in series with?) Why o why didn't i take the blue pill?
Based on the circuit recomendation in the DS, p.7: the two 47uF dc blockers, the two 6k8 phantom Rs, and the two 2k2 input Rs, oh and throw in the four in4148 Ds, how does this effect the input impedance? If someone could give me a straight answer as to how to calculate the impedances (in and out) i would forever be in your debt.
oh, i see no stated output impedance in the datasheet for this IC. Is this an "assumed" value? I'm lost. How is 60M||2pF useful?
Thanks, Ben.
Post script: I'm sure as with most things i've found a way to over complicate this.
How on earth do you calculate in/out impedance? If there are caps in the signal path at the input of a micamp (DC blocking) and i'm sure i've read that the impedance of a cap is dependant on frequency, is a stated input impedance referenced at a certain frequency?
....and, per the datasheet p.3 of the ina217, the input impedance is 60M||2pF. (in series with?) Why o why didn't i take the blue pill?
Based on the circuit recomendation in the DS, p.7: the two 47uF dc blockers, the two 6k8 phantom Rs, and the two 2k2 input Rs, oh and throw in the four in4148 Ds, how does this effect the input impedance? If someone could give me a straight answer as to how to calculate the impedances (in and out) i would forever be in your debt.
oh, i see no stated output impedance in the datasheet for this IC. Is this an "assumed" value? I'm lost. How is 60M||2pF useful?
Thanks, Ben.
Post script: I'm sure as with most things i've found a way to over complicate this.