BONDW1 to BONDW50 (Philips-TU Delft Bondwires Model)
Symbol
Available in ADS and RFDE
Parameters
Name | Description | Units | Default |
---|---|---|---|
Radw | Radius of the bondwires | um | 12.5 |
Cond | Conductivity of the bondwires | S | 1.3e7 |
View | (ADS Layout option) Determines top or side view, with the option to make segments visible or not | None | side |
Layer | (for Layout option) Layer to which the bondwire is drawn | None | cond |
SepX | Separation, incrementally added to each X offset | um | 0 |
SepY | Separation, incrementally added to each Y offset | um | 0 |
Zoffset | Base offset to add to all Z offsets | um | 0 |
W#_Shape | Shape reference (quoted string) for wire 1 | um | Shape1 |
W#_Xoffset | X offset for wire 1 | um | 0 |
W#_Yoffset | Y offset for wire 1 | um | 0 |
W#_Zoffset | Z offset for wire 1 | um | 0 |
W#_Angle | Rotation angle of wire 1 with respect to odd-numbered connections | deg | 0 |
Note: The block W#_Shape...W#_Angle is repeated for each individual wire. |
Notes
- The model is based on Koen Mouthaans model WIRECURVEDARRAY, which includes skin effects as well. The model calculates the effective inductance matrix of a set of mutually coupled bondwires as a function of the geometrical shape in space of the wires. The wire shapes must be linearized into 5 segments. To define the shape you should refer to a shape wire (like a BONDW_Shape or a BONDW_Usershape instance).
- Important: Some examples of symbols are provided in ADS in the Passive-RF Circuit component library palette (N=1,2,3,4,5,6,7,8,9,10, 20). Other BONDWxx components up to N=50 are also available in this ADS library but BONDW11 through BONDW19 and BONDW21 through BONDW50 are not presented in the component palette or library browser. These components can be accessed by typing their name in the component history field.
To use these components in a Schematic window, type the exact name (such as BONDW12) in the Component History field above the design area; press Enter; move the cursor to the design area and place the component.
Since the model inside the simulator works with any number of bondwires, ADS also gives users the capability to create larger bondwire components with their symbols. The component definitions and symbols from 1 to any N can be generated using the ADS Command Line by choosing Tools > Command Line from the ADS Main window. Type create_bondwires_symbol(N) where N is the maximum number of bondwires you need. A file called bondwires.ael with the component definitions and all the required symbol files will be created in the networks directory of your current project. Reopening the project will automatically load the bondwires.ael file, and the library nmglib_bondwires_new will be available in your library browser. - Introduction to Bondwire Components
The bondwire model is a physics-based model, calculating the self inductances and mutual inductances (the inductance matrix) of coupled bondwires. For the calculation of these inductances, Neumann's inductance equation is used in combination with the concept of partial inductances [1], [2]. The method of images is used to account for a perfectly conducting groundplane [6]. The DC- and AC-resistance of each wire are included in the model using a zero order approximation. - Bondwire Features and Restrictions
- Calculation of the self- and mutual inductance of coupled bondwires using Neumann's inductance equation.
- Each bondwire is represented by five straight segments.
- Cartesian ( x,y,z) coordinates for begin- and end-points of the segments are entered.
- Wires may not touch or intersect.
- A perfectly conducting groundplane is assumed at z=0.
- Capacitive coupling between bondwires is not accounted for.
- Capacitive coupling to ground is not accounted for.
- Loss, due to radiation is not considered.
- A change in the current distribution due to the proximity of other wires ( proximity effect ) is not included.
- DC losses, due to the finite conductivity of the wires is included.
- AC losses, due to the skin effect, are accounted for in a zero-th order approximation.
- Input Parameters of the Model
In modelling the bondwires, each bondwire is represented by five straight segments. This is illustrated in Piecewise Approximation of Bondwires on the right, wire is approximated by straight segments, where the SEM photo of a bondwire is shown: on the left two coupled bondwires are shown; on the right, five segments representing the bondwire are shown.
The bondwire model requires the following input parameters:- radius of the wires (meters)
- conductivity of the wires (Siemens/meter)
- view top, side, top (full), side (full)
- layer (cond, cond2, resi, diel, diel2. bond, symbol, text, leads, packages)
- begin point, intermediate points and endpoint of the segments in Cartesian coordinates (meters).
A perfectly conducting groundplane at z=0 is assumed. The presence of this groundplane normally reduces the inductance compared to the case of wires without such a groundplane.
Piecewise Approximation of Bondwires on the right, wire is approximated by straight segments
- Example Instance
The instance for three wires is shown in Instance of Bondwire Model for 3 Wires (BONDW3). The symbol BONDW3 defines the number of bondwires and their relative positions.
Instance of Bondwire Model for 3 Wires (BONDW3)
In this example, the input parameters are as follows.- RW, radius of the wires (meters). If the diameter of a wire is 25 um, the value of RW should be set to 12.5 um.
- COND, conductivity of the wire (Siemens/meter). If the wires have a conductivity of 1.3 10E+7 S/m the value of COND must be set to 1.3E7.
- VIEW set to default side
- LAYER set to default cond
- SepX = 0 is a constant separation in the x direction that is added incrementally to each wire.
- SepY = 200 um is a constant separation in the y direction, which is added incrementally to each wire. In the common case of parallel wires, this is the distance between wires.
- Zoffset = 0 is an offset added to each bondwire coordinates in the z-direction.
- Wi_Shape = "Shape1" defines the shape instance. It can be BONDW_Shape or BONDW_Usershape (as shown in Instance of Bondwire Model for 3 Wires (BONDW3)).
- Wi_Xoffset represents an offset added to each x coordinate of wire i (meters).
- Wi_Yoffset represents an offset added to each x coordinate of wire i (meters).
- Wi_Zoffset represents an offset added to each x coordinate of wire i (meters).
- Wi_Angle represents the rotation around a z axis through the bondwires i reference point (x1,y1,z1), away from the x direction (degrees).
A perfectly conducting groundplane is assumed at the plane z=0.
By choosing the BONDW_Usershape (Shape1 symbol), each wire is divided into 5 segments and the Cartesian coordinates of the begin and endpoints must be entered.
- What the Model Calculates
The model calculates the self and mutual inductances of wires. Capacitive coupling between wires or capacitive coupling to ground is not included, nor is radiation loss included. DC losses, due to the finite conductivity of the wires, is included. AC losses are included using zero-th order approximations for skin effect losses. The effect of proximity effects, when wires are located closely together, on the inductance and resistance is not included in the model. The model assumes a perfectly conducting ground plane at z=0. The presence of this groundplane normally reduces the inductance as compared to the case of wires without such a plane. Possible electromagnetic couplings between wires and other circuit elements are not accounted for. In conclusion, the model calculates the self- and mutual inductance of wires. DC losses are included and AC losses are approximately incorporated. - Restrictions on Input
The following illustrations demonstrate forbidden situations.- Wire segments must be fully located above the groundplane at z=0, as illustrated in Incorrect Application (on the left) Correct Application (on the right). To guarantee that the wire is fully located above the ground plane, add the wire radius in the BONDW_Shape component.
Incorrect Application (on the left)Correct Application (on the right)
- As shown in 90-degree Angle Not Sufficient, the angle between segments always must be greater than 90 degrees.
90-degree Angle Not Sufficient
- As shown in Non-adjacent Segments Touching, non-adjacent segments may not touch or intersect.
Non-adjacent Segments Touching
- Wire segments must be fully located above the groundplane at z=0, as illustrated in Incorrect Application (on the left) Correct Application (on the right). To guarantee that the wire is fully located above the ground plane, add the wire radius in the BONDW_Shape component.
- Example With a Single Bondwire
Example of a Bondwire Interconnecting a Substrate and a MMIC
For convenience, a grid with a major grid spacing of 100 um is also plotted. Using this grid, starting point, four intermediate points and end point are found as: (400,0,600), (500,0,700), (600,0,730), (800,0,650), (1000,0,420) and (1100,0,200) respectively (all in um). The radius of the wire is 20 um.
The representation of this wire in ADS is shown in Example of Single Bondwire. One wire in ADS uses the points (0,400,600), (0,500,700), (0,600,730), (0,800,650), (0,1000,420) and (0,1100,200) (in um) As a result of the simulation, the inductance is calculated as 0.730 nH.
Example of Single Bondwire
- Example With a Double Bondwire
Four bondwires are placed in parallel separated by 200 um as shown in Example of Four Wires in ADS; each bondwire has the shape used in Example of Single Bondwire. The inductance of the four parallel wires is calculated to be 278 pH. For simplicity, the four wires in this example are connected in parallel; with the model, it is easy to calculate mutual inductances in more complicated situations.
Example of Four Wires in ADS
- Neumann's Inductance Equation
The bondwire model calculates the inductance matrix of coupled bondwires using Neumann's inductance equation. The principle of this equation for closed loops is illustrated in Definition of Mutual Inductance. The mutual inductance Li,j between a closed loop Ci and a closed loop Cj is defined as the ratio between the flux through Cj, due to a current in Ci, and the current in Ci. The figure shows the definition of the mutual inductance between two current carrying loops as the ratio of the magnetic flux in contour Cj and the current in loop i.
In practice, however, bondwires are only part of a loop. To account for this effect, the concept of partial inductances is used [2]. This concept is illustrated in Definition of Mutual Inductance. This figure illustrates that the model calculates the partial inductance between the bondwires, ignoring possible couplings between the wires and other circuit elements.
Definition of Mutual Inductance
Loops Formed with Network Elements shows Current carrying loops formed with network elements. On the left, closed loops are shown using elements such as a capacitor, a resistor and a voltage source. Each loop also has a bondwire. If only the mutual inductance between the wires is of interest, the concept of partial inductance is used [2] where for reasons of simplicity the mutual coupling between the wires and the remaining network elements is assumed negligible. In this case Neumann's inductance equation is not applied to the closed contours, but to the wires only.
Loops Formed with Network Elements
Modelling of Bondwires in ADS shows modelling of bondwires in ADS. Inductive coupling is modelled by the inductance matrix L and resistive losses are modelled by a resistance matrix R.
Modelling of Bondwires in ADS
- Specification Coordinate Segments for Bondwire Components
This model calculates the real coordinate points xj(i),yj(i),zj(i) (j from 1 to 6) for the five wire segments of each bondwire i by using the corresponding reference coordinates Xj,Yj,Zj of the associated bondwire shape (e. g. the shape corresponding to the W i Shape parameter of wire _i ) and applying a rotation to it and two translations to them.
An Illustration of the Process of Rotation and Translation for the Top View of the Wire Above
The bondwire i reference shape is rotated over an angle of Wi_Angle degrees around a z axis through the "reference point" X1,Y1,Z1.
The first translation is over a distance ( (i-1) SepX, (i-1) SepY, Zoffset) associated with the general step for multiple wires and general height setting defined for the entire BONDW# component.
The second translation is an individual perturbation of the x,y,z positions of each wires with respect to the general stepping above and is defined by the individual Wi_Xoffset,Wi_Xoffset,Wi_Zoffset parameters.
This is expressed by the following equations that are valid for all BONDWx components:
xj(i) = SepX*(i-1) + Wi_Xoffset + X1 + (Xj - X1)*cos(Wi_angle) - (Yj-Y1)*sin(Wi_angle)
yj(i) = SepY*(i-1) + Wi_Yoffset + Y1 + (Xj - X1)*sin(Wi_angle) + (Yj-Y1)*cos(Wi_angle)
zj(i) = Zoffset + Wi_Zoffset + Zj - Generating Layout
A layout representation can be generated through the ADS Schematic window. After setting up wire shapes and bondwire components, choose Layout > Generate/Update Layout to generate a 2D visualization of the bondwires.
You can select a top or side view of the wires, with or without detail of the wire segments. The default representation is a side view in simple line art. When you select the View options side(full) or top(full), a representation showing the 5 segments per bondwire which are used inside the simulator is shown. You can use these two full views in case of setup problems with the bondwire shape components.
A bondwire simulation typically fails with errors when unexpected forms are shown, or overlap occurs, in these detail views. - Background
The bondwire model calculates self and mutual inductances of coupled bondwires and puts the values into an inductance matrix L. In addition the model calculates the DC and AC resistances assuming uncoupled bondwires. Changes in the current distribution within a wire due to a nearby located current carrying wire (proximity effect) are not accounted for. The DC and AC resistances are put into a resistance matrix R. The bondwire model is formed by placing the inductance matrix and the resistance matrix in series (Modelling of Bondwires in ADS). - Further Information
In the Ph.D. thesis of K. Mouthaan [5], the model and a comparison of the model with rigorous simulations and measurements, are described in detail. To obtain a copy of the dissertation, visit the internet site: www.DevilsFoot.com .
References
- F. W. Grover, Inductance Calculations Working Formulas and Tables. Dover Publications, Inc., New York, 1946.
- A.E. Ruehli, "Inductance calculations in a complex integrated circuit environment," IBM J. Res. Develop, pp. 470-481, September 1972.
- K. Mouthaan and R. Tinti and M. de Kok and H.C. de Graaff and J.L. Tauritz and J. Slotboom, "Microwave modelling and measurement of the self- and mutual inductance of coupled bondwires," Proceedings of the 1997 Bipolar/BiCMOS Circuits and Technology Meeting, pp.166-169, September 1997.
- A.O. Harm and K. Mouthaan and E. Aziz and M. Versleijen, "Modelling and Simulation of Hybrid RF Circuits Using a Versatile Compact Bondwire Model," Proceedings of the European Microwave Conference, pp. 529-534, Oct. 1998. Amsterdam.
- K. Mouthaan, Modelling of RF High Power Bipolar Transistors. Ph.D. dissertation, ISBN 90-407-2145-9, Delft University of Technology, 2001. To obtain a copy, visit the internet site: http://www.DevilsFoot.com.
- L.V. Bewly, Two dimensional fields in Electrical Engineering. Dover publication, Inc., New York, 1963.