Buffer

The Inverter/Buffer models a generic inverter and buffer. Perfectly complementary outputs are provided with both outputs changing state after the Propagation Delay.

In this topic:

  • Editing the Inverter/Buffer
  • Truth Table
  • Examples
  • Waveforms
  • Subcircuit Parameters

    • Model Name: Inverter/Buffer
    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 Library: SIMPLIS_DIGI1.LB
    Subcircuit Names:
    • SIMPLIS_DIGI1_BUF_N : Without Ground Reference
    • SIMPLIS_DIGI1_XBUF_Y : With Ground Reference
    Symbol:
    Without ground reference.
    Multiple Selections: Only one device at a time can be edited.

    Editing the Inverter/Buffer

    To configure the Inverter/Buffer, 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
    Propagation Delay Delay from when any input pin changes state until the outputs change state
    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.
    Initial Condition Initial condition of the Inverter/Buffer output at time=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:

    1. From the Edit Inverter/Buffer dialog box, 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 Inverter/Buffer input pin
    Hysteresis, Threshold Hysteresis and Threshold of the inputs. The hysteretic-window width, HYSTWD is centered around Threshold (TH) voltage. To determine the actual threshold ( TL , THI ), substitute Threshold (TH) and Hysteresis (HYSTWD) in each of the following formulas:
    Input Logic Level Actual Threshold
    1 Threshold + 0.5 * Hysteresis
    0 Threshold - 0.5 * Hysteresis
    Output Resistance Output resistance of each Inverter/Buffer output pin
    Output High Voltage Output high voltage for each Inverter/Buffer output pin
    Output Low Voltage Output low voltage for each Inverter/Buffer output pin

    Truth Table

    Input Outputs
    Buffer Inverter
    0 0 1
    1 1 0

    Examples

    The test circuit used to generate the waveform examples in the next section can be downloaded here: simplis_059_inverter_example.sxsch.

    Waveforms

    The waveforms below were taken from a simple inverter test circuit where the input is connected to a digital pulse source.

    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 an Inverter/Buffer with active-high inputs and without ground reference would be as follows: 
    X$U1 3 4 2 SIMPLIS_DIGI1_BUF_N vars: 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
    DELAY Propagation Delay Number 1f to 1024 s Delay from when any input pin changes state until the outputs change state
    GNDREF Ground Ref String
    • 'Y'
    • 'N'
    		 none 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.
    HYSTWD,
    TH    		 Hysteresis,
    Threshold    		 Number min: 1f V Hysteresis and Threshold of the inputs. The hysteretic-window width, HYSTWD is centered around Threshold (TH) voltage. To determine the actual threshold ( TL , THI ), substitute Threshold (TH) and Hysteresis (HYSTWD) in each of the following formulas:
    Input Logic Level Actual Threshold
    1 Threshold + 0.5 * Hysteresis
    0 Threshold - 0.5 * Hysteresis
    IC Initial Condition Number
    • 0
    • 1
    		 none Initial condition of the Inverter/Buffer output at time=0
    RIN Input Resistance Number min: 100 Ω Input resistance of each Inverter/Buffer input pin
    ROUT Output Resistance Number min: 1m Ω Output resistance of each Inverter/Buffer output pin
    VOH Output High Voltage Number any V Output high voltage for each Inverter/Buffer output pin
    VOL Output Low Voltage Number any V Output low voltage for each Inverter/Buffer output pin