How to model a SAW Filter

[Rayengine]

Hi,

For system simulation, it is easy to place a filter in the simulation. However, in circuit level or component level, how can we put a SAW filter in simulation? Any suggest good model for the simulation (the equv. L, C, R) circuit?

Thanks in advance!
Rayengine


Sorry: Double Post because of Network error, please delete one!

 

[yuhohang]

How about save the s-parameter of the SAW Filter and input to the simulator? All simulator could be input the s-parameter(Touch stone format) data for simulation

 

[Rayengine]

How about save the s-parameter of the SAW Filter and input to the simulator? All simulator could be input the s-parameter(Touch stone format) data for simulation

Thanks for your answer. Yes, S-parameter is good tool to perform simulator. But it is not a good tools to understand the behaviour model of the SAW filter. I want to go deeply into the SAW filter.

 

[MonkeyBusiness]

SAW filter can be modeled as multiple coupled resonators. In reality the resonators are mechanical, but you can model with electrical resonators.

Check http://www.tfrtech.com/pds/SU2002-3D-5.pdf for some further insight about how SAW devices work.

 

[dd22]

Saw filter modeling.

It puzzled me all the time.
For example, most of IF saw impedance are not 50 ohm. How would you like to measure the s-parameters? If you use balan, then how to convert?
If not, it is very difficult indeed, just think about a typical impedance of IF SAW 500-1000 and the standard 50 ohm for the network analyzer.
Can any one help this?
Thanks.

 

[flatulent]

conversions of S parameter base impedances

You can convert the 50 ohm S parameter measurements to any other basis impedance with some standard algebraic methods.

Since the SAW filters usually operate at lower frequencies, you can design discrete transistor amplifiers before and after them, optimized for the source and load they work between. The high impedance levels at these low frequencies will not cause much problems over the relative narrow filter bandwidth frequency range even if the amplifier gains drop way off out of band.

 

[u_f_o]

hi!
as i can remember there are 2 types of saw filters:
resonator filters and transversal filters.
all of you tell about are the resonator filters (imho).
it is right for these filters: the more bandwidth the less insertion loss.
these filters are possible to present in the manner of L-C-R-schemes.
another type is transversal filters.
these filters aren't possible to present in the manner of L-C-R-schemes.
it is right for these filters: the more bandwidth the more insertion loss.
best regards.
u_f_o

 

[ajar2dtn]

The following might be worth a look;

Understanding Surface Acoustic Wave (SAW) Devices for Mobile and Wireless Applications and Design Techniques
by Colin K. Campbell

**broken link removed**

 

[chiara]

Re: Saw filter modeling.

normally SAW provider supply the s-parameter of SAW filter with
matching ckt (LC) parameter...

for balance scheme they measure the s-parameter with
3-port or 4 -port VNA and match the filter with LC.
However, If you request the test sample....
they send test sample soldered on PCB with 1:1 or 4:1 balun
and balun loss data sheet...

As some guy said already... you can convert some s-parameter
with different reference impedance with easy math to which you want.

have a nice day

It puzzled me all the time.
For example, most of IF saw impedance are not 50 ohm. How would you like to measure the s-parameters? If you use balan, then how to convert?
If not, it is very difficult indeed, just think about a typical impedance of IF SAW 500-1000 and the standard 50 ohm for the network analyzer.
Can any one help this?
Thanks.