Doubts on SMT and Lumped Components in ADS

[pusparaga]

Dear Sir,
I have following doubts on SMT and Lumped Components in Advanced Design System

(1) As we know, lf we use lumped components ,while generating layout, it is not able to generate length and width of the component. In contrary, SMT components , they will generate length and width according to their series , example such as 0603 series different length and width, 0805 series different length and width, 1206 series different length and width. What is the difference between SMT and lumped component, if we use same value like 1pf lumped and 1pf SMT component value with different series such as 603,1206, etc.. , other than tolerance and width and length generating.

(2) Is there any value difference between Lumped and SMT components, suppose we use same 1KOhm lumped and 1Kohm SMT component value, other than layout generation purpose and tolerance value.

(3) What is the use of choosing different series such as 603, 805,1206,201 series for capacitor, inductor, and resistors of SMT components.

 

[RealAEL]

The SMT components are not ideal lumped elements but have models, extracted by the manufacturers, which simulate with realistic performance and not idealised performance of each device. You cannot see the models behind each of the SMT devices as these are encoded by the manufacturers but they are based on measurements of real devices. If you simply simulated ideal lumped components and compared them to the SMT components you would see the difference yourself.

 

[pusparaga]

Sir,
What is the importance in choosing series of each components, series such as 603,805,1206.
What is the main difference between model and ideal one.

 

[volker@muehlhaus]

What is the importance in choosing series of each components, series such as 603,805,1206.

The size of the component is different. See examples here:
https://en.wikipedia.org/wiki/Surface-mount_technology#Packages

What is the main difference between model and ideal one.

You can simulate an ideal component, but it does not exist in the real world. There are no ideal SMT elements.

Real world components are not ideal, and have additional effects: they have series inductance from their physical size, series inductance from losses etc. The model for SMT deviced includes these effects, so they describe the reality.

 

[pusparaga]

You can simulate an ideal component, but it does not exist in the real world.

Sir,
As you said , I agree with you. Even though what ever the SMT component values with their tolerance value are available in the ADS SMT library, Some values are not available in the real world. What ever real world existing values we used for the our design, it may give good results, but that component may not available in the SMT library. For example, 5.1PF with 0603 series is available in the real world, but the same 5.1 PF with 0603 series may not be available in the SMT library, nearer 5.6PF with 0603 may be available. In that case , mismatching of the real world value and the SMT library value, what decision we have to take. Either we have to choose the nearer value 5.6PF with 0603 series or we have to drop that value, whatever existing in the SMT library value, those values we have to search in the real world.

 

[volker@muehlhaus]

Even though what ever the SMT component values with their tolerance value are available in the ADS SMT library, Some values are not available in the real world. What ever real world existing values we used for the our design, it may give good results, but that component may not available in the SMT library. For example, 5.1PF with 0603 series is available in the real world, but the same 5.1 PF with 0603 series may not be available in the SMT library, nearer 5.6PF with 0603 may be available.

Tolerances are only one aspect. Also, the real capacitor has some series inductance, and some losses. The electrical behaviour is not exactly the same as the ideal capacitor with the same value.

In that case , mismatching of the real world value and the SMT library value, what decision we have to take. Either we have to choose the nearer value 5.6PF with 0603 series or we have to drop that value, whatever existing in the SMT library value, those values we have to search in the real world.

This is your engineering decision. You can change your design to work with existing component values that include the parasitic effects. That is where models make sense that describe the real component behaviour (and not just an ideal capacitor that doesn't exist in reality).

 

[RealAEL]

What is the main difference between model and ideal one.

For an overview of the model differences:-

SMT Capacitors
SMT Inductors
SMT Resistors

What value to choose is definitely a design decision that only you as the designer can make. You have to decide what trade-offs to make in the circuit performance to select from the available discrete component values. The SMT components are configured to support Discrete Optimization to assist in evaluating these different value combinations if desired.

 

[raju_kambar]

Dear Sir,
I have noticed one thing in the SMT Capacitors and SMT Resistors. For example you take AVX company 805 case style 1PF and kmt company 805 case style 1PF. The following doubts I have

(1) Is there any value difference in these two companies
(2) Is there any quality difference in these companies
(3) Price difference I have noticed in these companies
(4) For the same case style and same capacitor values and same resistance values ,why they have given so companies capacitors and resistors
(5) Are there any difference in these companies apart from price, tolerance values, and value of the capacitor.
Can you clarify these doubts.
kmt 1206 case style 1.5 PF value capacitor and Philips 1206 case style 1.5 PF value capacitor I have following doubts
(1) What is difference in these two values capacitor other than price , tolerance, and capacitor values
(2) Why they have given separately these transistor companies same case style and same value of the capacitors
Can you anybody clarify these doubts
I have attached the AVX and KEMET company 805 case style 1PF value capacitors . KEMET and PHILIPS company 1.5 PF 1206 case style capacitors have shown in the following attachment

 

[BigBoss]

Sir,
As you said , I agree with you. Even though what ever the SMT component values with their tolerance value are available in the ADS SMT library, Some values are not available in the real world. What ever real world existing values we used for the our design, it may give good results, but that component may not available in the SMT library. For example, 5.1PF with 0603 series is available in the real world, but the same 5.1 PF with 0603 series may not be available in the SMT library, nearer 5.6PF with 0603 may be available. In that case , mismatching of the real world value and the SMT library value, what decision we have to take. Either we have to choose the nearer value 5.6PF with 0603 series or we have to drop that value, whatever existing in the SMT library value, those values we have to search in the real world.

Download Design Kit of a manufacturer-for instance Murata- than install this DK in ADS.
You will see many capacitor and inductor values that are very close to your simulation values especially low cap and inductor values.
https://www.murata.com/products/design_support/lib/index.html#tab

 

[pusparaga]

Dear Sir,
I have shown in the following figures of JOHNSON market available capacitors, where these same JOHNSON part numbers, case style available for download and installation in the ADS SMT library. I have searched it,couldn't get the same part number with different tolerances and same style. If anybody knows, can show link for these market available JOHNSON capacitors.