Datasheet

AD9122
Rev. B | Page 37 of 60
.
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 and not
by the pass-band flatness. Table 16 shows the pass-band flatness
and stop-band rejection supported by the HB1 filter 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
MAGNITUDE (dB)
FREQUENCY (× f
IN1
) (Hz)
40
08281-022
Figure 52. Pass-Band Detail of HB1
Table 16. HB1 Pass-Band and Stop-Band Performance by
Bandwidth
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 0.0076 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
MAGNITUDE (dB)
FREQUENCY (× f
IN2
) (Hz)
.0
MODE 0
MODE 2 MODE 6
MODE 4
08281-023
Figure 53. HB2, Even Filter Modes
0
–20
–40
–60
–80
–100
021.81.61.41.21.00.80.60.40.2
MAGNITUDE (dB)
FREQUENCY (× f
IN2
) (Hz)
.0
MODE 1
MODE 3
MODE 7
MODE 5
08281-024
Figure 54. HB2, Odd Filter Modes
As shown in Figure 53 and Figure 54, the center frequency in
each mode is offset by one-fourth 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 operating in Mode 0 and Mode 4, the I and Q paths
operate independently and no mixing of the data between chan-
nels occurs. When operating 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 to be complex.