Zeropoles plots for filters
zplane(Hq)
zplane(Hq,plotoption
)
zplane(Hq,plotoption
,plotoption2
)
zplane(Hq,Name,Value)
[zq,pq,kq]
= zplane(Hq)
[zq,pq,kq,zr,pr,kr]
= zplane(Hq)
zplane(
plots
the zeros and poles of a quantized filter Hq
)Hq
in
the current figure window. The poles and zeros of the quantized and
unquantized filters are plotted by default. The symbol o
represents
a zero of the unquantized reference filter, and the symbol x
represents
a pole of that filter. The symbols
and +
are used
to plot the zeros and poles of the quantized filter Hq
.
The plot includes the unit circle for reference.
zplane(
plots
the poles and zeros associated with the quantized filter Hq
,plotoption
)Hq
according
to one specified plot option. The string plotoption
can
be either of the following reference filter display options:
'on'
to display the
poles and zeros of both the quantized filter and the associated reference
filter (default)
'off'
to display the
poles and zeros of only the quantized filter
zplane(
plots
the poles and zeros associated with the quantized filter Hq
,plotoption
,plotoption2
)Hq
according
to two specified plot options. The string plotoption
can
be selected from the reference filter display options listed in the
previous syntax. The string plotoption2
can
be selected from the sectionbysection plotting style options described
in the following list:
'individual'
to display
the poles and zeros of each section of the filter in a separate figure
window
'overlay'
to display
the poles and zeros of all sections of the filter on the same plot
'tile'
to display the
poles and zeros of each section of the filter in a separate plot in
the same figure window
zplane(
returns
a phase response with additional options specified by one or more Hq
,Name,Value
)Name,Value
pair
arguments. Namevalue pair arguments are only available if Hq
is
a filter System object™.
[
returns the vectors of
zeros zq
,pq
,kq
]
= zplane(Hq
)zq
, poles pq
, and gains kq
.
If Hq
has n sections, zq
, pq
,
and kq
are returned as 1byn cell
arrays. If there are no zeros (or no poles), zq
(or pq
)
is set to the empty matrix []
.
[
returns the vectors of zeros zq
,pq
,kq
,zr
,pr
,kr
]
= zplane(Hq)zr
,
poles pr
, and gains kr
of the
reference filter associated with the quantized filter Hq
.
It also returns the vectors of zeros zq
, poles pq
,
and gains kq
for the quantized filter Hq
.

Zeros of quantized filter. 

Poles of quantized filter. 

Gains of quantized filter. 

Zeros of reference filter. 

Poles of reference filter. 

Gains of reference filter. 
Create a quantized filter Hq
from a fourthorder
digital filter with cutoff frequency of 0.6. Plot the quantized and
unquantized poles and zeros associated with this quantized filter.
[b,a] = ellip(4,.5,20,.6);
Hq = dfilt.df2(b, a);
Hq.arithmetic = 'fixed';
zplane(Hq);