
286 Analog Electronics
open loop gain of the opamps, rather than bot-
toming out at R2 as in the case of the Figure 11.7
circuit; that is, the Q of the inductor holds up much
better at low frequencies. Furthermore, the
opamp performance requirements by way of
CMRR and input bias current are relaxed. The
left-hand opamp is an integrator and the other two
are current sources, defined by the resistors. The
resistors should all be 1% types, and the resistors
shown dashed may be needed to guarantee stab-
ility of the synthetic inductor in the event of an
unfortunate worst case spread of resistor values:
they can be say 100 times the value of the othe ...