Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

IIR Filter could be causal or always non causal

Status
Not open for further replies.

bhq

Member level 5
Joined
Jun 11, 2008
Messages
80
Helped
9
Reputation
18
Reaction score
2
Trophy points
1,288
Activity points
1,711
I want to know that Is IIR filter is always non causal. if not than please send me an example of IIR Filter in difference equation that is causal.

Please think about

y(n) = y(n-1) + x(n-1) + 2*x(n)

Is the above system is causal or non causal?
Is the system is IIR or not ?
 

nalino

Full Member level 3
Joined
Dec 11, 2003
Messages
170
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,298
Activity points
650
this is a causal system as y(n) only relies on it's past values y(n-1) and x's present and past values...transfer function is

y(n) = y(n-1) +2*x(n) + x(n-1)
Y(z) = Y(z)*z^-1 + 2*X(z) + X(z)*z^-1
H(z) = Y(z)/X(z) = (2+z^-1)/(1-z^-1)

=> 1st order low-pass filter..
 

xulfee

Advanced Member level 1
Joined
May 27, 2008
Messages
401
Helped
45
Reputation
100
Reaction score
14
Trophy points
1,298
Location
Pakistan
Activity points
2,904
this system is causal the example u given
 

    bhq

    Points: 2
    Helpful Answer Positive Rating

premkiran

Newbie level 5
Joined
Mar 16, 2007
Messages
9
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Activity points
1,337
The filter equation , written by you, is a causal iir filter.

Only the required specifications in designing a filter , can drive you either to causal/non causal filer equations.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top