Reference: https://docs.myhdl.org/en/stable/manual/reference.html#myhdl.ResetSignal

--- pyfda/hdl_generation/filter_iir.py.orig	2017-01-10 06:40:25 UTC
+++ pyfda/hdl_generation/filter_iir.py
@@ -3,9 +3,6 @@
 # Copyright (c) 2011, 2015 Christopher L. Felton
 #
 
-from __future__ import absolute_import
-from __future__ import print_function
-from __future__ import division
 
 """
 IIR Hadward Filter Generation
@@ -243,7 +240,7 @@ class FilterIIR(object):
             return iir
 
         clock = Signal(False)
-        reset = ResetSignal(0, active=1, async=False)
+        reset = ResetSignal(0, active=1, isasync=False)
         x = Signal(intbv(0, min=-imax, max=imax))
         y = Signal(intbv(0, min=-imax, max=imax))
         xdv, ydv = Signal(bool(0)), Signal(bool(0))
@@ -268,7 +265,7 @@ class FilterIIR(object):
         self.Nfft = Nfft
         w = self.word_format[0]
         clock = Signal(bool(0))
-        reset = ResetSignal(0, active=1, async=False)
+        reset = ResetSignal(0, active=1, isasync=False)
         sigin = FilterInterface(word_format=self.word_format)
         sigout = FilterInterface(word_format=self.word_format)
         xf = Signal(0.0)    # floating point version