Transimpedance Networks
3-10
Figure 3-10. Simplified EVM Schematic for Noninverting Gain
-
+
U1
THS4601
2
3
6
7
4
R3
J3
Vout
R4
VS-
J2
Vin+
Z6
VS+
Z4
3.5
Transimpedance Networks
The components R4, and Z4 through Z6 can be used to form several
transimpedance networks. Transimpedance networks are used to implement
custom filter responses based on the location of poles and zeros. Pole / zero
filter design is beyond the scope of this EVM manual. There are many excellent
textbooks on the subject that the reader should consult. Figures 3-11 through
3-15 show some of the networks that can be implemented. Location of poles,
as an X on an imaginary/real axis, and location of zeros as O are shown.
The output of the THS4601 is modeled as a ground because the ideal op amp
model has zero-
Ω
output impedance.
Figure 3-11. Single Real Pole
Vin
Iout
R4
X
Z6
Imag
Real
Z4
Figure 3-12. Single Real Zero
R4+Z4
Vin
Z5
Imag
O
Real
Iout