@Christopher2222 I know this,I do this in Maple,not in Mathematica.

@Christopher2222 I know this,I do this in Maple,not in Mathematica.

The workaround you propose is only applied to some special case,how can I smooth the following curves?

with(DynamicSystems):

sys:=TransferFunction([1],[1,1]):

PhasePlot(sys)

The workaround you propose is only applied to some special case,how can I smooth the following curves?

with(DynamicSystems):

sys:=TransferFunction([1],[1,1]):

PhasePlot(sys)

When antialiasing is set to false,the curve is like the first one,

When antialiasing is set to true,the curve is like the second one,

but both of them cannot get the effect of Mathematica.

When antialiasing is set to false,the curve is like the first one,

When antialiasing is set to true,the curve is like the second one,

but both of them cannot get the effect of Mathematica.

@Carl Love 

I don't know the default number of points used in Mathematica,but it seems that it doesn't work to increase the number of points in Maple.