tidy3d.LinearLumpedElement#

class LinearLumpedElement[source]#

Bases: RectangularLumpedElement

Lumped element representing a network consisting of resistors, capacitors, and inductors.

Parameters:
  • attrs (dict = {}) – Dictionary storing arbitrary metadata for a Tidy3D object. This dictionary can be freely used by the user for storing data without affecting the operation of Tidy3D as it is not used internally. Note that, unlike regular Tidy3D fields, attrs are mutable. For example, the following is allowed for setting an attr obj.attrs['foo'] = bar. Also note that Tidy3D` will raise a TypeError if attrs contain objects that can not be serialized. One can check if attrs are serializable by calling obj.json().

  • center (Union[tuple[Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box]], Box] = (0.0, 0.0, 0.0)) – [units = um]. Center of object in x, y, and z.

  • size (Union[tuple[Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box]], Box]) – [units = um]. Size in x, y, and z directions.

  • name (ConstrainedStrValue) – Unique name for the lumped element.

  • num_grid_cells (Optional[PositiveInt] = 1) – Number of mesh grid cells associated with the lumped element along each direction. Used in generating the suggested list of MeshOverrideStructure objects. A value of None will turn off mesh refinement suggestions.

  • enable_snapping_points (bool = True) – When enabled, snapping points are automatically generated to snap grids to key geometric features of the lumped element for more accurate modelling.

  • voltage_axis (Literal[0, 1, 2]) – Specifies the axis along which the component is oriented and along which the associated voltage drop will occur. Must be in the plane of the element.

  • snap_perimeter_to_grid (bool = True) – When enabled, the perimeter of the lumped element is snapped to the simulation grid, which improves accuracy when the number of grid cells is low within the element. Sides of the element perpendicular to the voltage_axis are snapped to grid boundaries, while the sides parallel to the voltage_axis are snapped to grid centers. Lumped elements are always snapped to the nearest grid boundary along their normal_axis, regardless of this option.

  • network (Union[RLCNetwork, AdmittanceNetwork]) – The linear element produces an equivalent medium that emulates the voltage-current relationship described by the network field.

  • dist_type (Literal['off', 'laterally_only', 'on'] = on) – Switches between the different methods for distributing the lumped element over the grid.

Notes

Implementation is based on the equivalent medium introduced by [1].

References

Example

>>> RL_series = RLCNetwork(resistance=75,
...                        inductance=1e-9,
...                        network_topology="series"
...             )
>>> linear_element = LinearLumpedElement(
...                         center=[0, 0, 0],
...                         size=[2, 0, 3],
...                         voltage_axis=0,
...                         network=RL_series,
...                         name="LumpedRL"
...                   )

Attributes

Methods

admittance(freqs)

Returns the admittance of this lumped element at the frequencies specified by freqs.

estimate_parasitic_elements(grid)

Provides an estimate for the parasitic inductance and capacitance associated with the connections.

impedance(freqs)

Returns the impedance of this lumped element at the frequencies specified by freqs.

to_PEC_connection(grid)

Converts the LinearLumpedElement object to a Structure, representing any PEC connections.

to_structure(grid)

Converts the LinearLumpedElement object to a Structure, which enforces the desired voltage-current relationship across one or more grid cells.

to_structures(grid)

Converts the LinearLumpedElement object to a list of Structure which are ready to be added to the Simulation

Inherited Common Usage

network#
dist_type#

An advanced feature for LinearLumpedElement is the ability to choose different methods for distributing the network portion over the the Yee grid. When set to on, the network portion of the lumped element is distributed across the entirety of the lumped element’s bounding box. When set to off, the network portion of the lumped element is restricted to one cell and PEC connections are used to connect the network cell to the edges of the lumped element. A third option exists laterally_only, where the network portion is only distributed along the lateral axis of the lumped element.

When using a dist_type other than on additional parasitic network elements are introduced, see below. Thin connections lead to a higher inductance, while wide connections lead to a higher parasitic capacitance. Follow the link to the associated notebook for an example of using this field.

../../_images/lumped_dist_type.png
to_structure(grid)[source]#

Converts the LinearLumpedElement object to a Structure, which enforces the desired voltage-current relationship across one or more grid cells.

to_PEC_connection(grid)[source]#

Converts the LinearLumpedElement object to a Structure, representing any PEC connections.

to_structures(grid)[source]#

Converts the LinearLumpedElement object to a list of Structure which are ready to be added to the Simulation

estimate_parasitic_elements(grid)[source]#

Provides an estimate for the parasitic inductance and capacitance associated with the connections. These wire or sheet connections are used when the lumped element is not distributed over the voltage axis.

Notes

These estimates for parasitic inductance and capacitance are approximate and may be inaccurate in some cases. However, the formulas used should be accurate in the important regime where the true values for inductance and capacitance are large. For example, the estimate for capacitance will be more accurate for wide elements discretized with a high resolution grid.

Returns:

A tuple containing the parasitic series inductance and parasitic shunt capacitance, respectively.

Return type:

tuple[float, float]

admittance(freqs)[source]#

Returns the admittance of this lumped element at the frequencies specified by freqs.

Note

Admittance is returned using the physics convention for time-harmonic fields \(\exp{-j \omega t}\), so the imaginary part of the admittance will have an opposite sign compared to the expected value when using the engineering convention.

impedance(freqs)[source]#

Returns the impedance of this lumped element at the frequencies specified by freqs.

Note

Impedance is returned using the physics convention for time-harmonic fields \(\exp{-j \omega t}\), so the imaginary part of the impedance will have an opposite sign compared to the expected value when using the engineering convention.

__hash__()#

Hash method.