Consider the following transfer functions:

1. 

2.  

3.  

The transfer functions which have a linear phase are:

Concept:

Linear phase

FIR filters can satisfy a linear phase response if the impulse response is symmetric or anti-symmetric.

• For symmetric impulse response phase will be θ(ω) = - α ω

• For anti-symmetric impulse response will be θ(ω) = - α × ω + β

Calculation:

Given system 1 is

The phase of this system is

θ₁(ω) = - α ω

So this is the linear phase.

Given system 2 is

The phase of this system is

θ₂(ω) = - α ω

So this is the linear phase.

Given system 3 is

The phase of this system is

θ₃(ω) = - α ω

So this is the linear phase.

All are linear phase systems