Environmental Engineering Reference
In-Depth Information
To calculate the closed-loop input and output resistances we can derive
and
directly from (6.48). Thus we have
and the input and output resistances are
6.4 SERIES-SERIES AMPLIFIER
Fig. 6.24 depicts the AC schematic of the series-series feedback
amplifier. Three transistors, T1, T2, and T3, are embedded in the open loop
amplifier and the feedback subcircuit is provided by resistor combined
with local feedback resistors and The feedback network samples the
output current, and compares it with the input voltage. Therefore, both
the driving point input and output resistance are very high, and, accordingly,
the circuit operates best as a transconductance amplifier in that its closed
loop transresistance, is nominally invariant with source
resistance, load resistance and transistor parameters.
