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4.2 Netlist Elements 457
For infinite gain, value gm must be Infinity. Note that, functionally, an OTAmp is the same as a
voltage-controlled current source. The difference to a VCCSource is that during circuit equation
setup another matrix fill-in pattern is used which makes limit calculations for large OTAmp gains
easier.
4.2.17 Nullator
type name
syntax
Nullator {NULname, {node1, node2}, 0}
denotes a nullator
Circuit element type Nullator.
node1
I=0
V=0
node2
A nullator is an ideal two-terminal circuit element which enforces both a zero voltage and a zero
current between its terminals. It is thus neither a voltage nor a current source but rather both at
the same time. The value specification in the netlist entry of a nullator is irrelevant and should be
set to 0 (zero). Note that an element with a arbitrary but fixed branch current and branch voltage
is also known as a fixator. With a zero current and voltage, a nullator is a special case of a fixator.
A nullator usually appears paired with a norator, thus forming a nullor. A nullor represents a
controlled source of arbitrary type with infinite gain, such as an ideal operational amplifier.
4.2.18 Norator
type name
syntax
Norator {NORname, {node1, node2}, 0}
denotes a norator
Circuit element type Norator.