TFC (Thin Film Capacitor) SmartComponent

Symbol

Parameters

Name	Description	Unit	Default
F	Center frequency	GHz	1
C	Capacitance	pF	1
W	Conductor width	mil	25
T	Thickness of capacitor dielectric	mil	0.2
Er	Relative dielectric constant	None	9.6
Rho	Resistivity of conductor (relative to gold)	None	1
TanD	Dielectric loss tangent	None	0
CO	Conductor overlap	mil	0
DO	Dielectric overlap	mil	0
Delta	Length added to conductor for tuning capacitance	mil	0

Notes

1. TFC designs a thin film capacitor. The underlying design uses the TFC component contained in the Tlines-Microstrip palette.
2. The design is accomplished by determining the length required to achieve the desired capacitance using the simple parallel plate capacitor model C = Er*W*L/T. The parameters from Rho through DO inclusive are not used in the design process but are passed on to the underlying TFC component and are therefore included in any simulations or optimizations.
3. The tuning parameter Delta represents incremental length required to achieve the desired capacitance. It is typically relatively small, as the initial design tends to be accurate.
4. The Optimization Assistant tunes the conductor length to achieve the desired capacitance.
5. A SmartComponent subnetwork is empty until the Design Assistant is used to generate the design. Refer to Design Assistant.

Example

A TFC component was used to design a 1 pF capacitor at a center frequency of 5 GHz using a dielectric with a 0.2 mil thickness and dielectric constant of 9.6. Optimization yielded a value of Delta = -0.000178 mil.