Positive-phase AC amplifier circuit that can increase input impedance 10 times

Since the OP amplifier requires the inverting input terminal and the non-inverting input terminal to be at the same
potential when working, the output voltage of the voltage divider circuit at this time is e. Reduce Rz/one (Chou soil + BI) times t
and then the following formula can be listed:
    ·__ Rl
    _' =B t
    e- said z + Ra
    according to the definition of amplification coefficient; A ce. /e. , this is a familiar formula.
    Because the AC amplifier circuit uses a capacitor, the low-condensation characteristic is
    I J...a
,. , = Lord Eph. , Er_ and, mouth z = 2; rCl. Month: Synthesis, but usually connected to jf loss summer ", ¨
1殳 meter mouth cut-off frequency by G. Fourth, decide. In the AC amplification circuit , the OP amplifier is selected based on
the highest rated string number and the required gain
. To use it
as a negative feedback amplifier,
a loop gain of at least 20dB is required. If A
= 20dB, = iookHz, RJ must choose an OP amplifier
with an open-loop gain of 40dB (
at 100 kHz) or above .