SIMPLIS Parts

OR/NOR Gate

The OR/NOR Gate models a generic OR or NOR gate with up to nine inputs. The number of active-low inputs can be set to one less than the total number of inputs. Both OR and NOR outputs are provided. The outputs change state at the same time, making the outputs perfectly complementary.

To implement a logic gate with more than nine inputs, see SIMPLIS Digital Lookup Table and SIMPLIS Lookup Table with Don't Care Input Definitions

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Model Name:

OR/NOR Gate

Simulator:

This device is compatible with the SIMPLIS simulator.

Parts Selector
Menu Location:

Digital Functions | Gates

Symbol Library:

None - the symbol is automatically generated when placed or edited.

Model File:

SIMPLIS_DIGI1.lb

Subcircuit Name:

  • SIMPLIS_DIGI1_ORX_N: Without Ground Reference
  • SIMPLIS_DIGI1_ORX_Y: With Ground Reference
The "X" in each subcircuit name is an integer from 2 to 9 representing the total number of inputs. For example, SIMPLIS_DIGI1_OR3_N is a 3-input OR/NOR gate.

Symbol:

Multiple Selections:

Multiple OR gates can be selected and edited at the same time.

Editing the OR/NOR Gate

To configure the OR/NOR gate, follow these steps:

  1. Double click the symbol on the schematic to open the editing dialog to the Parameters tab.
  2. Make the appropriate changes to the fields described in the table below the image.
Label Parameter Description

Delay

Delay from when any input pin changes state until the outputs change state

# of Logic Inputs

Number of active-high logic inputs

# of Inverted Logic Inputs

Number of active-low logic inputs. Any device can have active-low inputs up to the # of Logic Inputs minus 1.

Ground Ref

Determines whether or not a device has a ground reference pin.

Any digital component that has an input or output pin connected to an analog circuit node must have its Ground Ref pin connected to an analog node. This is usually the ground on the schematic. Click on the Help button for more information.

Initial Condition

Initial condition of the OR output at t=0

To define the parameters for the interface between this digital component and each analog component connected directly to an input or output pin, follow these steps from the Edit OR/NOR Gate dialog box:

  1. Click on the   Interface   tab.
  2. Make the appropriate changes to the fields described in the table below the image.
Label Parameter Description

Input Resistance

Input resistance of each input pin

Threshold

Hysteresis

The Threshold (T) and Hysteresis (H) of the Schmitt trigger input buffer on each OR / NOR Gate input. To determine the low-to-high threshold (TH) and the high-to-low threshold (TL), substitute Threshold (T) and Hysteresis (H) in each of the following formulas :
Input Logic Transition Actual Threshold
0 ➞ 1 TH = Threshold + 0.5 * Hysteresis
1 ➞ 0 TL = Threshold - 0.5 * Hysteresis
 

Output Resistance

Output resistance of each output pin

Output High Voltage

Output high voltage for each output pin

Output Low Voltage

Output low voltage for each output pin

Truth Table

The following truth table is for a two-input OR/NOR gate with active-high inputs.

Inputs

Outputs

A

B

OR

 NOR

0

0

0

 1

0

1

1

 0

1

0

1

 0

1

1

1

 0

Examples

The test circuit used to generate the waveform examples in the next section can be downloaded here: simplis_057_orgate_example.sxsch.

Waveforms

The waveforms below were taken from a 3-input OR/NOR gate with two active-high inputs and one active-low input. The two active-high inputs are labelled A and B, and the active-low input is labelled C. With this configuration, the OR output will be high when either of the A and B inputs are high or the C input is low.

Subcircuit Parameters

The subcircuit parameters, parameter names, data types, ranges, units, and descriptions are in the following table. The parameter names can be used to directly generate netlist entries for the device. For example, the netlist entry for a 3-input OR/NOR Gate with 1 inverted input and without ground reference would be as follows:
X$U1 6 9 2 3 4 SIMPLIS_DIGI1_OR3_N vars: NumInv=1 IC=0 RIN=10Meg ROUT=10 HYSTWD=1 VOL=0 VOH=5 DELAY=2p TH=2.5


Parameter Name Label Data Type Range Units Parameter Description

NumInv

# of Inverted Logic Inputs

  

0 to # of Logic Inputs

  

Number of active-low logic inputs. Any device can have active-low inputs up to the # of Logic Inputs minus 1.

DELAY

Delay

  

1f to 1024

s

Delay from when any input pin changes state until the outputs change state

HYSTWD

Hysteresis

    

V

The Threshold (T) and Hysteresis (H) of the Schmitt trigger input buffer on each OR / NOR Gate input. To determine the low-to-high threshold (TH) and the high-to-low threshold (TL), substitute Threshold (T) and Hysteresis (H) in each of the following formulas :

Input Logic Transition Actual Threshold
0 ➞ 1 TH = Threshold + 0.5 * Hysteresis
1 ➞ 0 TL = Threshold - 0.5 * Hysteresis
 

IC

Initial Condition

LIST

0,
1

  

Initial condition of the OR output at t=0

RIN

Input Resistance

  

min: 100

Ω

Input resistance of each input pin

VOH

Output High Voltage

    

V

Output high voltage for each output pin

VOL

Output Low Voltage

    

V

Output low voltage for each output pin

ROUT

Output Resistance

  

min: 1m

Ω

Output resistance of each output pin

TH

Threshold

    

V

The Threshold (T) and Hysteresis (H) of the Schmitt trigger input buffer on each OR / NOR Gate input. To determine the low-to-high threshold (TH) and the high-to-low threshold (TL), substitute Threshold (T) and Hysteresis (H) in each of the following formulas :

Input Logic Transition Actual Threshold
0 ➞ 1 TH = Threshold + 0.5 * Hysteresis
1 ➞ 0 TL = Threshold - 0.5 * Hysteresis