BTGRP

Model

Note: The zigzag line represents the resistive element between the bidirectional ports.

Description

The BTGRP primitive is a non-ideal switch element with configurable ON-resistance. The resistance is specified by assigning a SERIES-DEPTH (SDEPTH) value upon instantiating the switch in a SNL PART statement.

BTGRP: Enabled when its control input, C, is a logical-0 (negative enabled)

The SDEPTH value can range from 1 to 32766, where:

• 1 = minimum resistance of the switch
• 32766 = maximum resistance of the switch
• If unspecified, the SDEPTH value defaults to 1

Charge Storage Considerations

It is important that charge-storage be modeled reasonably in switch networks (i.e. decays are larger than delays), otherwise the simulation could produce transient X pulses, slowing down the simulation throughput and possibly generating oscillations during network value convergence.

Compiler Optimization

SIMIC optimizes switch level networks during compilation:

• Merging paralleled gates
• Converting bidirectional BTGRPs to unidirectional UTGRPs where possible

This optimization improves simulation throughput by reducing bidirectional signal propagation to unidirectional flow where the circuit topology allows it.

Equivalent Type Statement

Type=BTGRP i=C b=B[1],B[2] sdepth=1

Example Usage

PART=sw1 TYPE=btgrp I=enable B=node_a,node_b SDEPTH=5

Notes

• BTGRP is a resistive switch with configurable ON-resistance
• This switch is bidirectional—signal flow can occur in either direction
• The SDEPTH parameter controls the switch's ON-resistance (1=minimum, 32766=maximum)
• SIMIC automatically converts BTGRPs to unidirectional UTGRPs where possible for better performance
• For ideal switches with zero resistance, see BTGP primitive
• For positive enabled resistive switch, see BTGRN primitive
• Proper charge storage modeling (decays > delays) is essential to avoid transient X pulses