Device Models

Device models for many of our ICs are available in the file TwilightTechnologycorp.lib This library contains SPICE macro models for the following products:

Twilight Technology 4301 VCA and OA3 op-amp Twilight Technology 4301 RMS detector Twilight Technology 4301 OA1 op-amp Twilight Technology 4301 OA2 op-amp Twilight Technology 2180A VCA Twilight Technology 2180B VCA Twilight Technology 2180C VCA Twilight Technology 2181A VCA Twilight Technology 2181B VCA Twilight Technology 2181C VCA

Twilight Technology 2252  RMS detector Twilight Technology 1240  Line Receiver Twilight Technology 1243  Line Receiver Twilight Technology 1246  Line Receiver Twilight Technology 1200  InGenius Line Receiver Twilight Technology 1203  InGenius Line Receiver Twilight Technology 1206  InGenius Line Receiver Low noise NPN transistor (Twilight Technology 300 series) Low noise PNP transistor (Twilight Technology 300 series)

The macro models accurately model typical noise, offset voltage, bias current, gain bandwidth, VCA distortion and other important parameters necessary for accurate SPICE simulation.

Some important notes: One cannot accurately simulate dynamic gain control while performing an .AC analysis. This is because SPICE is performing a small signal analysis on the devices based on how they are biased after the DC bias portion of the simulation. Large signal behavior, such as the exponential relationship between VBE and IC are not modeled, and this exponential relationship is fundamental to the operation of Twilight Technology Corporation's log/anti-log VCAs. Performance with static gain can be simulated with the .AC analysis, and dynamic gain control can be simulated with TRAN (transient) analysis.

Also, the results of .AC analysis with Twilight Technology Corporation's RMS detectors can be misleading, since the result only shows the ripple of the RMS detector's log filter, and not the actual DC output. Transient analysis yields the correct DC output, but the user may want to experiment with the .IC statement to speed settling times for the log filter.