diff --git a/lib/radio/nco/src/tb_nco_cordic.vhd b/lib/radio/nco/src/tb_nco_cordic.vhd
index 2d1401e..2cac587 100644
--- a/lib/radio/nco/src/tb_nco_cordic.vhd
+++ b/lib/radio/nco/src/tb_nco_cordic.vhd
@@ -37,6 +37,7 @@ ARCHITECTURE behavior OF tb_nco IS
 	GENERIC 
 	(
 		nbits_wave		: integer;
+		nbits_wave_frac	: integer;
 		nbits_phase		: integer
 		);
 	PORT(
@@ -61,7 +62,7 @@ ARCHITECTURE behavior OF tb_nco IS
 	constant df : REAL := 10.0E3;
 	constant fa : REAL := 100.0E6;
 	constant PERIOD : time := 10 ns;
-	constant nbits_wave_frac : integer := nbits_wave;
+	constant nbits_wave_frac : integer := nbits_wave-2;
 	
 	SIGNAL freq_word : integer := integer(f/fa*2.0**nbits_phase);
 	SIGNAL dfreq_word : integer := integer(df/fa*2.0**nbits_phase);
@@ -92,6 +93,7 @@ BEGIN
 	GENERIC MAP
 	(
 		nbits_wave		=> nbits_wave,
+		nbits_wave_frac	=> nbits_wave_frac,
 		nbits_phase		=> nbits_phase
 	)
 	PORT MAP