Topic:		 		ICAP/4Windows
Description: 		CAE Software; New Native Mixed Mode Circuit Simulation Program
Price:	 			$2595, Update $295
Contact:			Charles Hymowitz - Vice President intusoft   (310) 833-0710, Fax (310) 833-9658
					E-mail 74774.2023@compuserve.com


New SPICE Simulates Sampled Data Filters

The new version of IsSpice4 has been enhanced with a powerful Native
Mixed Mode simulation capability.  Unlike SPICE 3, which is designed
mainly for analog simulation and based exclusively on matrix solution
techniques, IsSpice4 includes BOTH analog (SPICE 3F) and event driven
simulation algorithms in the same executable.  Thus, designs that
contain significant portions of digital circuitry can be efficiently
simulated together with the analog components.  The event driven
algorithm in IsSpice4 is unique.  It not only supports 12 state digital
data, but also other types including real, integer, and a user
definable data type.  This capability is very useful for simulating DSP
functions and sampled data filters in an analog environment.  IsSpice4
is the only interactive Windows based SPICE 3 simulator to offer this
feature.

As an example of this "multi" mixed mode feature a MIDI (Musical
Instrument Digital Interface) synthesizer circuit was simulated by
IsSpice4.  MIDI is used as a gateway between the analog world of music
and the digital world of computers.  The results are presented in
November issue of Intusoft's free SPICE Newsletter.

Simulation of the system involves three types of data; digital, which
has 12 states, real which has continuous values, and analog voltages
and currents.  The circuit includes a digital oscillator, a frequency
divider, a sampled-data filter, and a low-pass filter.  The MIDI VCO
(numerically controlled oscillator model) produces a digital square
wave based on the input bits (MIDI note).  The sampled data filter uses
real values and is composed of gain and Z-1 transform models. 
Translational bridges are used to convert between the different signal
types.  The input is translated from a digital state to a real value
using the D-to-R node bridge.  The enable on the D-to-R bridge is
driven by the MIDI note on/off bit.  The output is converted to an
analog signal through a real-to-analog bridge and a low pass filter. 
The data types are signified by the letters D, R, and A on the
schematic.

A key aspect of IsSpice4 is that the real data is handled by the event
driven simulator.  Thus, the sampled-data filter is simulated much more
quickly than if analog models are used.  It should also be noted that
models in IsSpice4 are not restricted to one type of data.  As in the
case of the sampled data filter both digital and real are used.  The
circuit simulates in under 10s on a Pentium/90.