- 10 0meg Zout In Ohms 6 00meg 2 00meg 2 00meg 10k Os 1 100k 1 Meg 10meg 100meg Frequency In Hz Fig 8 The Output I 1 (115.43 KiB) Viewed 21 times
10.0Meg Zout in ohms 6.00Meg 2.00Meg -2.00Meg 10k OS -1 + + 100k 1 Meg 10Meg 100Meg frequency in Hz Fig. 8. The output impedance of the circuit of Fig. 2 simulated, using the original circuit and the ones derived from the application of Miller's Theorem and FDT. Based on the equivalent circuit of Fig. 6, we calculated the output impedance as follows: Zou = You? = (y2, +y_)', with y = g.V/V. =, V But V, =sC, R ' +R'+s(C, +C)I'V, and Zour finally yields: R+R+SRRC, +C) (23), SC (R+R + RR)+s’RRCC, which we cross-checked it as identical to the Zour calculated directly from the original circuit of Fig. 2. Comparing the two approaches, it is apparent that (19) and (21) give the same dc input impedances, equal to Rs+Ri, but somewhat different frequency response. Their percentage dif- ference depends on the actual values of the original circuit [8]. From (21) and (23) we can conclude that the output impedance Z our