C_TFG

	C_TFG Coplanar Thin-Film Resistor to Ground Parameters Notes Equivalent Circuit
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Coplanar Thin-Film Resistor to Ground

The C_TFG module represents a resistive connection between the inner line and the ground planes of a coplanar line. The distance between the innerline and the ground planes in resistive section (resistor length) is given in a line type addressed by C_LTYPR. The total width of the resistor is given by L. The dimensions of connected lines at ports are defined using data items addressed by C_ LTYP1 and C_LTYP2.

Parameters

Parameter	Description	Range of Usage
L	Total width of the resistor
C_LTYPC	ID of coplanar transmission line applied at resistive section
C_LTYP1	ID of coplanar transmission line applied at ports 1
C_LTYP2	ID of coplanar transmission line applied at ports 2
RES_IDX	Index to sheet resistivity definition in currently selected foundry
C_SUB	ID of coplanar substrate definition
C_GRID	ID of simulation control data
TEMP	ID of element temperature definition used for noise computation

Notes

Presently, the C_TRG module is not able to calculate the steps which are made if different line types are used for C_LTYP1, C_LTYP1 and C_LTYPR. Therefore, if a step configuration is used for layout reasons, the effect of such discontinuities are not taken into account during the simulation.
L is the total width of the resistor. Note that the effective width of the resistive section is given by L- 2.res_l. Therefor L has to be greater than 2.res_l.
CEN_MET and GND_MET in C_LTYP1 and C_LTYP2 must have the same value. These values are also used for the resistive section. The Parameter CEN_MET and GND_MET in C_LTYPR are ignored.
The index RES_IDX is used for the selection of the desired resistive layer in selected foundry. In case of DEFAULT foundry, one resistive layers is available, so that only DIE_IDX=1 is valid.
If L1 in selected C_GRID is not set to –1 or –2 (auto sizing), the minimum values for L1 is:

L1_min= max( W1+2S1+2GW1, W2+2S2+2GW2, WR+2SR+2GWR)

Equivalent Circuit

For the modeling of the C_TFG element, a distributive equivalent circuit is used. Since the traveling wave effects along the resistor is taken into account, , there is no limitation due to the length L. The model parameter are derived from quasi-static FD-calculations. The DC and RF losses (represented by R´) due to the skin effect are calculated using the surface current distribution on the conductors.