Datasheet

AD9125
Rev. 0 | Page 33 of 56
.
Figure 52 shows the pass-band filter response for HB1. In most
applications, the usable bandwidth of the filter is limited by the
image suppression provided by the stop-band rejection, not by
the pass-band flatness. Table 17 shows the pass-band flatness
and stop-band rejection that the HB1 filter supports at different
bandwidths.
0.02
–0.10
–0.08
–0.06
–0.04
–0.02
0
000.360.320.280.240.200.160.120.080.04
GAIN (dB)
NORMALIZED FREQUENCY (× f
IN1
)
40
09016-022
Figure 52. Pass-Band Detail of HB1
Table 17. HB1 Pass-Band Flatness and Stop-Band Rejection
Bandwidth (% of f
IN1
)
Pass-Band
Flatness (dB)
Stop-Band
Rejection (dB)
80 0.001 85
80.4 0.0012 80
81.2 0.0033 70
82.0 0.0076 60
83.6 0.0271 50
85.6 0.1096 40
Half-Band Filter 2 (HB2)
HB2 has eight modes of operation, as shown in Figure 53 and
Figure 54. The shape of the filter response is identical in each of
the eight modes. The eight modes are distinguished by two factors:
the filter center frequency and whether the input signal is
modulated by the filter.
0
–20
–40
–60
–80
–100
021.81.61.41.21.00.80.60.40.2
GAIN (dB)
NORMALIZED FREQUENCY (× f
IN2
)
.0
MODE 0
MODE 2 MODE 6
MODE 4
09016-023
Figure 53. HB2, Even Filter Modes
0
–20
–40
–60
–80
–100
021.81.61.41.21.00.80.60.40.2
GAIN (dB)
NORMALIZED FREQUENCY (× f
IN2
)
.0
MODE 1
MODE 3
MODE 7
MODE 5
09016-024
Figure 54. HB2, Odd Filter Modes
As shown in Figure 53 and Figure 54, the center frequency in
each mode is offset by ¼ of the input data rate (f
IN2
) of the filter.
Mode 0 through Mode 3 do not modulate the input signal.
Mode 4 through Mode 7 modulate the input signal by f
IN2
.
When HB2 operates in Mode 0 and Mode 4, the I and Q paths
operate independently and no mixing of the data between
channels occurs. When HB2 operates in the other six modes,
mixing of the data between the I and Q paths occurs; therefore,
the data input to the filter is assumed complex.