Appeal No. 2000-0142 Page 3
Application No. 08/705,569
current to the reference resistor. A current amplifier
generates a second current. The input of the current
amplifier is connected to the output of the differential
amplifier. The differential amplifier is provided with a low-
pass filter. The components of the current amplifier, on one
hand, and the current generator and reference resistor, on the
other hand, are mutually exclusive. The ballast circuit is
also provided with a current control circuit coupled to the
current amplifier and to the current generator for influencing
the first current dependent upon the second current. The
mutual exclusivity and the current control circuit ensure that
an interference signal present at the second input causes no
appreciable interference in the second current.
Claim 18, which is representative for present purposes,
follows:
18. A voltage-to-current converter comprising:
a reference resistor,
first means for supplying a first current to the
reference resistor,
a differential amplifier having a first input
terminal for connection to a source of reference
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