User Guide

PSpice-equivalent parts
177
In controlled sources, EXPR may contain constants and
parameters as well as voltages, currents, or time. Voltages
may be either the voltage at a net, such as V(5), or the
voltage across two nets, such as V(4,5). Currents must be
the current through a voltage source (V device), for
example, I(VSENSE). Voltage sources with a value of 0 are
handy for sensing current for use in these expressions.
Functions may be used in expressions, along with
arithmetic operators (+, -, *, and /) and parentheses.
Available built-in functions are summarized in Table 10
on page 3-71.
The EVALUE and GVALUE parts are defined, in part, by
the following properties (default values are shown):
EVALUE
EXPR V(%IN+, %IN-)
GVALUE
EXPR V(%IN+, %IN-)
Sources are controlled by expressions which may contain
voltages, currents, or both. The following examples
illustrate customized EVALUE and GVALUE parts.
Example 1
In the example of an EVALUE device shown in Figure 49,
the output voltage is set to 5 volts times the square root of
the voltage between pins %IN+ and %IN-.
The property settings for this device are as follows:
EXPR = 5v * SQRT(V(%IN+,%IN-))
Example 2
Consider the device in Figure 50. This device could be
used as an oscillator for a PSK (Phase Shift Keyed)
modulator.
A current through a source is a sine wave with an
amplitude of 15 mA and a frequency of 10 kHz. The
voltage at the input pin can shift the phase by 1
radian/volt. Note the use of the TIME parameter in this
Figure 49 EVALUE part example.
Figure 50 GVALUE part example.
Pspug.book Page 177 Wednesday, November 11, 1998 1:14 PM