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# Coplanar Gap C_GAP

### Symbol :

### Illustration :

### Parameters :

> L1 = Length of transmission line connected to the port 1.
> L2 = Length of transmission line connected to the port 2.
> GAP = Gap spacing
> C_LTYP1 = ID of coplanar transmission line applied at port 1
> C_LTYP2 = ID of coplanar transmission line applied at port 2
> C_SUB = ID of coplanar substrate definition
> C_GRID = ID of simulation control data
> TEMP = ID of element temperature definition used for noise computation

### Range of Usage :

> GAP = 0.5.n.DL* n=1,2,3,...
> * ) see C_GRID for information on DL

### Notes/Equations/References :

> 1. The C_GAP module represents a gap between the center conductors of two coplanar lines. The dimensions of lines connected to the gap are defined using data items addressed by C_ LTYP1 and C_TYP2. GAP is the spacing between the lines. L1 and L2 are the lengths of connected coplanar lines at ports.
> 2. A negative value for L1 or L2 can be meaningful during the simulation. In such cases, the automated layout generation works incorrectly and the generated layout has to be edited manually.
> 3. C_LTYP1 and C_LTYP2 must have the same CEN_MET.
> 4. The difference between the center line widths (W2-W1) has to be an integer multiple of DL. Otherwise the simulator will shift the line at port 1 by a half of grid size (DL/2). In this case the gap will become asymmetrical and the user get the message: “(W2-W1)/DL no integer ® asymmetrical gap”. Please not that this change is not considered by layout generation. The layout of a gap is always symmetrical.
> 5. If W1+2S1+2GW1 ¹ W2+2S2+2GW2, there could be an step in the outer contour of the ground strips. In this case, the ground width of the line with smaller value of W+2S+2GW is increased (see layout), so that there is no step in the outer contour of ground planes. This change is considered by the simulation and layout generation.
> 6. If W1<W2 and W1+2S1>W2+2S2 (or W2>W1 and W1+2S1<W2+2S2), the step in the inner contour of ground planes is shifted by GAP (see layout). This change is considered by the simulation and layout generation.
> 7. If L1 and L2 in selected C_GRID are not set to –1 or –2 (auto sizing), the minimum values for L1 and L2 are:
>    L1min=max( W1+2*S1+2*GW1, W2+2*S2+2*GW2)
>    L2min=8*DL{C_GRID}+GAP
> 8. See notations in chapter 4 (Important Note!) for the correct selection of the C_LTYP1, C_LTYP2.

### Equivalent Circuit :

> For the modeling of the C_GAP element, a p-network of equivalent capacitances is used. The value of these capacitances is derived from electric charge calculations. The connected line at ports are modeled as C_LIN elements and are represented by their characteristic impedance ZL and phase constant b. There is no limitation due to the length of connected line (L)

### Layout :

> 1. If W1+2S1+2GW1 ¹ W2+2S2+2GW2, the ground width of the line with smaller value of W+2S+2GW is changed (no step in the outer contour of ground planes).
> 2. If W1+2S1 > W2+2S2, the step in the ground planes is shifted by GAP.
> 3. For L1=L2=0 only the ground planes in the gap section are drawn as layout.
> 4. If the parameter GW_DEF in C_PROCES is set to a positive non-zero value, this value is used as ground width for layout generation.

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