Is the input impedance your only specification? Don't you also have to meet a frequency response spec?Zin = (Vin-Va)/R1?
(Vin-Va)/R1 isn't we wil obtain current? by the way, Va is same as Vc1 right?
Actually, the problem is to fulfill the specification which our
Zin >= 10kOhm
So if i put the R1 = 10kohm is also satisfy the specification right?
Zin = 1/jwC1 + R2||(R2+1/jwC2) is wrong?