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Coplanar Thinfilm Resistor C_TFR

Symbol :

Illustration :

Parameters :

L = Total length of the resistor
C_LTYPR = ID of coplanar transmission line applied at resistive section
C_LTYP1 = ID of coplanar transmission line applied at port 1
C_LTYP2 = ID of coplanar transmission line applied at port 2
RES_IDX = Index to sheet resistivity (ohm/square) definition in currently selected foundry (res_rs)
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/Equations/References :

  1. The C_TFR module represents a series thin film resistor between two coplanar lines. The dimensions of lines are defined using data items addressed by C_ LTYP1 and C_LTYP2 (see C_LINTYP in chapter 4).
  2. The width of resistor and its distance to the ground are given in a line type addressed by C_LTYPR. L is the length of resistor including the resistive region res_l (see Illustration).
  3. Note that the effective length of the resistive section is given by L-2*res_l. L has to be greater than 2*res_l.
  4. Presently, the C_TFR 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.
  5. The parameter RES_IDX indicates the index of used resistive layer in the selected foundry. In case of DEFAULT foundry, RES_IDX is always 1.
  6. If L1 in selected C_GRID are not set to –1 or –2 (auto sizing), the minimum value for L1 is:
    L1min=max( W1+2*S1+2*GW1, W2+2*S2+2*GW2, WR+2*SR+2*GWR)
  7. See notations in chapter 4 (Important Note!) for the correct selection of the C_LTYP1, C_LTYP2 and C_LTYPR.

Equivalent Circuit :

For the modeling of the C_TFR element, a distributive equivalent circuit is used and the model parameter are derived from quasi-static FD-calculations. since traveling wave effects are considered, there is no limitation due to the length of resistor. The connected lines at ports are modeled as C_LIN elements and are represented by their characteristic impedance ZL and phase constant b.

Layout :

  1. 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. In this case the length of connected lines have to be greater than zero.



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