TFR (Thin Film Resistor) SmartComponent

Symbol

Parameters

Name	Description	Unit	Default
Subst	Microstrip substrate name	None	MSub1
F	Center frequency	GHz	1
R	Resistance	Ohm	50
W	Conductor width (set to 0 if Zo specified)	mil	0
Zo	Characteristic impedance of line assuming Rs; set to 0 if W specified	Ohm	50
Rs	Sheet resistivity (Ohms/square)	Ohm	50
Freq	Frequency for scaling sheet resistivity	Hz	0
CO	Conductor overlap	mil	0
Delta	Length added to conductor for tuning resistance	mil	0

Notes

1. TFR designs a thin film resistor. The underlying design uses the TFR component contained in the Tlines-Microstrip palette.
2. The design is accomplished by determining the length required to achieve the desired resistance using the sheet resistivity Rs in conjunction with the strip width W. The parameters Freq and CO are not used in the design process but are passed on to the underlying TFR component and are therefore included in any simulations or optimizations.
3. Since this resistor is often fed with a microstrip line, either the physical width or the characteristic impedance of a microstrip line on the substrate can be specified.
4. The tuning parameter Delta represents incremental length required to achieve the desired resistance.
5. The Optimization Assistant tunes the conductor length to achieve the desired resistance.
6. A SmartComponent subnetwork is empty until the Design Assistant is used to generate the design. Refer to Design Assistant.

Example

A TFR component was used to design a 50 Ohm resistor at a center frequency of 5 GHz using a conductor with a sheet resistance of 50 Ohm/square. The conductor width was chosen to correspond to that of a 50 Ohm microstrip line on the substrate. Optimization yielded a value of Delta = -3.549 mil.

Passive Circuit DG - Couplers