CMOS AND
CMOS logic circuits.
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Description
The CMOS blocks are CMOS logic gates. The truth table shows the dependence of the output logic level of CMOS blocks on their input level.
Block |
Input logic level of the block |
Output logic level of the block |
CMOS AND |
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|
all other values |
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CMOS BUFFER |
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|
all other values |
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CMOS NAND |
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|
all other values |
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CMOS NOR |
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|
all other values |
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CMOS NOT |
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all other values |
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CMOS OR |
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all other values |
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CMOS XOR |
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all other values |
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The block defines the logic levels of the valve inputs as follows:
-
If the voltage at the valve is greater than the threshold voltage, the block interprets the input as logic
1
. -
Otherwise the block interprets the input as logic
0
.
The Threshold Voltage is the voltage value at the midpoint between the value of the High level input voltage parameter and the value of the Low level input voltage parameter.
To increase the speed of the simulation, the block does not model all the internal individual MOSFET devices that make up the valve. Assumptions and limitations. |
Unit models the valve as follows:
-
The inputs of the valve have infinite resistance and finite or zero capacitance.
-
The output of the valve offers a choice of two models:
Linear
andQuadratic
. Use the Output current-voltage relationship parameters to specify the output model. -
You can specify the propagation delay for both valve models. For the
Linear
output, the block sets the value of the output capacitor of the valve so that the resistor-capacitor time constant is equal to the value of the Propagation delay parameters. For the `Quadratic' output, the input demand of the valve is delayed to approximate the value of the Propagation delay parameters.
The initial block conditions depend on the selected output model:
-
For the
Linear
model, a high initial condition corresponds to the value of the High level output voltage parameter,V_OH
, and a low initial condition corresponds to the value of the Low level output voltage parameter,V_OL
. -
For the `Quadratic' model, the high initial state is the value close to the value of the Supply voltage parameter, `Vcc', and the low initial state is the value of `0'.
The output voltage of the unit depends on the selected output model:
-
For the
Linear
model, a high output value is the value of the High level output voltage parameter and a low value is the value of the Low level output voltage parameter. -
For the
Quadratic
model, the output voltage for theHigh
andLow
states is a function of the output current. At zero load current, the high level output voltage isVcc
(the value of the Supply voltage parameters) and the low level output voltage is0
.
Constructing the waveform of the input and output signals
You can plot the input and output waveforms of the CMOS NOT block without building a complete model. Use these graphs to study the effect of your selected parameters on the performance of the unit.
-
If you set the block parameters based on a data table, you can compare your graphs to the data table to make sure you set the block parameters correctly.
-
If you have a complete working model but are unsure which manufactured part to use, you can compare your graphs to the datasheets to help you decide.
Assumptions and limitations
This block does not model the internal individual MOSFET devices that make up the valve (except for the last pair of MOSFETs if you have selected Quadratic
for the Output current-voltage relationship parameters). This limitation has the following implications:
-
The block does not accurately model the valve response to input noise and inputs near the logic threshold voltage.
-
The block does not accurately model the dynamic response.
In circuits with feedback around a set of logic gates, it may be necessary to set a non-zero propagation delay on one or more gates.
Ports
Conserving
#
J
—
output J
electricity
Details
Non-directional port associated with the J block output.
Program usage name |
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#
A
—
input A (for AND, NAND, NOR, OR or XOR)
electricity
Details
A non-directional port associated with the A input of the unit.
Dependencies
To use this port, set Type to AND, NAND, NOR, OR or XOR.
Program usage name |
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#
B
—
input B
electricity
Details
Non-directional port associated with the B input of the unit.
Dependencies
To use this port, set Type to AND, NAND, NOR, OR or XOR.
Program usage name |
|
#
A
—
input A (for BUFFER or NOT)
electricity
Details
A non-directional port associated with the A input of the unit.
Dependencies
To use this port, set Type to BUFFER or NOT.
Program usage name |
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Parameters
Main
#
Type —
CMOS type
AND
| BUFFER
| NAND
| NOR
| NOT
| OR
| XOR
Details
The Type parameter makes it possible to change the CMOS type without recreating a new component. The following values are possible:
-
Components with two input ports:
-
AND
-
NAND
-
NOR
-
OR
-
* XOR
-
-
Components with one input port:
-
BUFFER
-
NOT
-
Dependencies
You need to rebuild the circuit when switching a dual-port component to a single-port component or vice versa.
Values |
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Default value |
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Program usage name |
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Evaluatable |
No |
Inputs
#
Low level input voltage —
lower threshold voltage at the input
V
| MV
| kV
| mV
Details
The voltage value below which the block interprets the input voltage as a logical `LOW'.
Values |
|
Default value |
|
Program usage name |
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Evaluatable |
Yes |
#
High level input voltage —
upper threshold voltage at the input
V
| MV
| kV
| mV
Details
The voltage value above which the unit interprets the input voltage as logic `HIGH'.
Values |
|
Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Average input capacitance —
average input capacitance
F
| mF
| nF
| pF
| uF
Details
A fixed capacitance that approximates the input capacitance for the gate of a transistor. The capacitance of a MOSFET depends on the applied voltage.
If you control this block with another valve, the Average input capacitance sets the voltage rise time, similar to the transistor voltage rise time. You can usually find the value of this capacitance in the manufacturer’s data sheet.
Setting this parameter to 0 may result in faster simulation times.
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Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
Outputs
#
Output current-voltage relationship —
relationship between output current and voltage
Linear
| Quadratic
Details
Output signal model. The following values are possible:
-
Linear
. -
Quadratic
Values |
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Default value |
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Program usage name |
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Evaluatable |
No |
#
Low level output voltage —
lower output threshold voltage
V
| MV
| kV
| mV
Details
The value of the output voltage below which the unit sets the output voltage as logic `LOW'.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Linear
.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
High level output voltage —
upper threshold output voltage
V
| MV
| kV
| mV
Details
The value of the output voltage above which the unit sets the output voltage as logic `HIGH'.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Linear
.
Values |
|
Default value |
|
Program usage name |
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Evaluatable |
Yes |
#
Output resistance —
output impedance
Ohm
| GOhm
| MOhm
| kOhm
| mOhm
Details
The resistance value of the series output resistor, which is used to simulate the output voltage drop caused by the output current. You can obtain this value from the product data sheet or technical specification catalogue by dividing the high level output voltage by the maximum low level output current.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Linear
.
Values |
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Default value |
|
Program usage name |
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Evaluatable |
Yes |
#
Supply voltage —
power supply voltage
V
| MV
| kV
| mV
Details
The value of the power supply voltage applied to the valve in your circuit.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to `Quadratic'.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Measurement voltage —
signal voltage
V
| MV
| kV
| mV
Details
Valve supply voltage for which the output resistances and currents of the reference data are determined.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to `Quadratic'.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Logic HIGH output resistance at zero current and at I_OH —
output resistance at the HIGH
state on the valve at zero current and at current
Ohm
| GOhm
| MOhm
| kOhm
| mOhm
Details
Vector [ ] containing two resistance values.
-
- is the gradient of the output voltage/current dependence when the valve is in the logic
HIGH
state and there is no output current. -
- is the gradient of the current dependence of the output voltage when the valve is in the logic
HIGH
state and the output current is .
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Quadratic
.
Values |
|
Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Logic HIGH output current I_OH when shorted to ground —
output current for earth faults
A
| MA
| kA
| mA
| nA
| pA
| uA
Details
The magnitude of current when the valve is in the logic HIGH
state and the load causes the output voltage to tend to zero.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to `Quadratic'.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Logic LOW output resistance at zero current and at I_OL —
output resistance at the LOW
state on the valve at zero current and at current
Ohm
| GOhm
| MOhm
| kOhm
| mOhm
Details
Vector [ ] containing two resistance values.
-
- is the gradient of the output voltage/current dependence when the valve is in the logical
LOW
state and there is no output current. -
- is the gradient of the current dependence of the output voltage when the valve is in the logical
LOW
state and the output current is .
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Quadratic
.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Logic LOW output current I_OL when shorted to Vcc —
output current at LOW
state on the valve when is shorted on the valve
A
| MA
| kA
| mA
| nA
| pA
| uA
Details
The magnitude of current when the valve is in the logic LOW
state but the load forces the output voltage to reach the supply voltage .
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to Quadratic
.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Propagation delay —
signal propagation delay
d
| s
| hr
| ms
| ns
| us
| min
Details
The time for a signal to go from LOW
to HIGH
or from HIGH
to LOW
after a change in input logic levels.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Protection diode on resistance —
resistance of the open protective diode
Ohm
| GOhm
| MOhm
| kOhm
| mOhm
Details
Voltage-current gradient for protection diodes at direct bias.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to `Quadratic'.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
#
Protection diode forward voltage —
protection diode forward voltage
V
| MV
| kV
| mV
Details
Voltage above which the protection diode opens.
Dependencies
To use this parameter, set the Output current-voltage relationship parameter to `Quadratic'.
Values |
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Default value |
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Program usage name |
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Evaluatable |
Yes |
Initial Conditions
#
Output initial state —
initial output state
Low
| High
Details
Specify the initial output state of the block as High
or Low
.
This parameter is used for both linear and quadratic output models, provided that the Propagation delay parameter is greater than zero and the Start simulation from steady state parameter is turned off in the block Solver Configuration.
Values |
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Default value |
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Program usage name |
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Evaluatable |
No |