Environmental Engineering Reference
In-Depth Information
thus, as clearly indicated by the approximated relation (6.44) we globally get
the expected increase in the output resistance
6.3 SHUNT-SHUNT AMPLIFIER
The AC schematic diagram of the third type of single loop feedback
amplifier, the shunt-shunt amplifier, is drawn in Fig. 6.19. A cascade
interconnection of three transistors, T1, T2 and T3, forms the open loop,
while the feedback subcircuit comprises a single resistance, The output
voltage, is sampled by and converted into a current which is fed back
to the input port. Therefore, both the driving point input and output
resistance are very small. Accordingly, the circuit operates best as a
transresistance amplifier in that its closed loop transresistance,
is nominally invariant with source resistance, load resistance and
transistor parameters.
Considering the equivalent small-signal model of shunt-shunt circuit
shown in Fig. 6.20, we can arbitrarily choose transconductance
as
