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Coplanar Bridgetype Data Definition C_AIRTYP

Symbol :

Illustration :

Parameters :

TYPE = identifies the metal level of bridge (TYPE=0 ® no bridge )
BW = bridge width
BG = bridge gap
BS = bridge spacing (BS= -1 ® BS = S of connected Linetype )
DIE_IDX = index to the dielectric layer definition for bridges in selected foundry
L = length of feed line connected to the bridge

Range of Usage :

TYPE = 0, 1, 2, -1 (see illustration)
BW = 0.5.n.DL* n=1,2,3,...
BG = 0.5.n.DL* n=0,1,2,3,...
BS = 0.5.n.DL* n=1,2,3,... (or –1)
DIE_IDX = (0, 1 or 2 in DEFAULT foundry)
* ) see C_GRID for information on DL

Notes/Equations/References :

  1. The C_AIRTYP data item describes the construction of air bridges used in junctions and spiral inductors.

  2. The value of TYPE defines the metal level of the bridge (the connection of the two ground planes). Two different options (TYPE=1 and TYPE=2) are available for the air bridge element (C_AIR) and all other structures which contain bridges (C_BEND, C-TEE, C_CROSS and C_RIND). In addition, for the junction elements C_BNED, C_TEE and C_CROSS a special bridge type TYPE= –1 is also available (see illustration). TYPE=0 switches off the bridge definition. TYPE=0 is not allowed for C_AIR and C_RIND.
  3. The correct chose of TYPE depends on value of CEN_MET in C_LINTYP of the connected lines. TYPE and CEN_MET can not have the same value.
  4. If TYPE=0 is selected, the parameter BW and BG are not set automatically to zero! In this case, the bridge removed but a piece of coplanar line with the length of (BW+2BG+2L) will remain. This ensure that the reference planes of the element are not changed if the air bridge is switched off.
  5. If TYPE=0 or BS = -1 or BS>S, BS will be set automatically equal to S (S is the slot of the line type C_LINTYP connected to the bridge). In case of C-RIND, BS is always set equal to the slot between the turns of inductor (ST in C_RIND).
  6. The dielectric used under the bridge is defined in the foundry data item C-TECH (parameter die_ern, die_hn, and die_tdn with n=0,1,2). DIE_IDX indicates the corresponding index n of dielectric parameter in C_TECH data item. In case of DEFAULT fondry DIE_IDX can have the values 0,1 or 2. For example, if DIE_IDX=0, die_h0 will be the bridge height, die_er0 the dielectric constant of the dielectric under the bridge and die_td0 the tangent loss of this dielectric. See C_TECH for more information on dielectric layer parameters.
  7. L is the length of the coplanar line connected to the bridge at ports of related element (see illustration for TYPE= –1). The configuration of the feed line connected to the bridge is given in the C_LINTYP data item of the corresponding element. For example, in the above illustration bridges are used in C_BEND element, each air bridge is connected with a piece of coplanar line of length L at ports of C_BEND. In case of C_AIR, the same line length L is connected to the both ports (as shown in the illustration). L is ignored in case of C_RIND.
  8. A zero or negative value for L can be meaningful during the simulation. For L<0, the automated layout generation works incorrectly and the generated layout has to be edited manually.


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