What is lead-lag filter used for?

[virus]

   +---||---+
   |        |
0--+--VVVV--+--VVVV--0

0--------------------0 GND

Hello all,
Is this a kind of filter?

Could anyone please explain it? Any web reference would be highly appreciated.

Thanks.

 

[eda4you]

lead-lag filter

   +---||---+
   |        |
0--+--VVVV--+--VVVV--0

0--------------------0 GND

Hello all,
Is this a kind of filter?

Could anyone please explain it? Any web reference would be highly appreciated.

Thanks.

Hi Virus!

something is wrong with your description! The second resistor in series makes no sense! If the circuit is as you described, the Transfercharacteristic is (for Rload= ∞ Ω) T=1!! However, it will vary with Rload.

 

[virus]

lag lead filter circuit

Thanks very much for your reply.

Yes. You're correct.
I missed the the RL. Anyway I have no idea it should be on left side or right side. Let assume there is a RL there...either at left side or right side.
Yes I know it would be different in both cases. But could someone please explain?

Thanks.

 

[usernam]

lead-lag filters

Thanks very much for your reply.

Yes. You're correct.
I missed the the RL. Anyway I have no idea it should be on left side or right side. Let assume there is a RL there...either at left side or right side.
Yes I know it would be different in both cases. But could someone please explain?

Thanks.

Maybe this link will help.
**broken link removed**

I still casn't make out what you mean by RL. Are you talking abt RLC or just RL??

 

[virus]

lead lag filter

Hi usernam,
Thanks for the reference.

It seems like a bit hard...
Give me some time to understand it before I come back.

 

[eda4you]

lead or lag filter

This is a lead-lag filter!

for very high frequ. and very low frequ. you have a phase shift of 0°. At high f you have a gain of 1, while at low R2/(R1+R2).

The tranferfunction is:

T(s) = A0 (1+j*ω1)/(1+j*ω2)

A0 = R2/(R1+R2)
ω1 = C1*R1
ω2 = ω1 * A0

 

[markty]

purpose of lead lag filter

Hi eda4you,

Can u explain what is leag-lag filter? what application need this circuit?

thanks,
mark

 

[eda4you]

lead/lag filter

There are many application. F.e. in PLLs. Look at

**broken link removed**

 

[zmliu]

lead lag filters

If R_C, lead-lag filter.If L-C, ladder filter.

 

[Vamsi Mocherla]

lead lag filter design

Well, Lead Lag filter can be used in many applications where you need a phase shift after certain frequencies.

 

[flushrat]

+lead lag filter

lead lag filters are used in plls, this book Phase-Locded Loops Deisign Simulation and Application (5th Edition) analysis lead lag filters, although the structure in this book is a little different from abrove picture.