AD9148 Analog Devices, AD9148 Datasheet - Page 51

• Manufacturer Part Number: AD9148
• Manufacturer: Analog Devices

Specifications of AD9148

• Resolution (bits): 16bit
• Dac Update Rate: 1GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: LVDS,Par

Data Sheet
Table 18. Programmable Inverse Sinc Filter Coefficient Widths and Ranges
Coefficient
c
c
c
c
c
c
c
c
c
c
The real and imaginary filters are implemented using the
structure described in Figure 62 and Figure 63.
The
processing of the filter coefficients based on the DAC sampling
frequency, the amount of interpolation used (combination of
HB1, HB2, and HB3), and the desired center frequency. This
center frequency is limited to
The bandwidth of the inverse sinc filter equals the maximum
allowable signal bandwidth of the interpolation filters (0.8 × f
INPUT
INPUT
0
0
1
1
2
2
3
3
4
4
in-phase (real)
quadrature (imaginary)
in-phase (real)
quadrature (imaginary)
in-phase (real)
quadrature (imaginary)
in-phase (real)
quadrature (imaginary)
in-phase (real)
quadrature (imaginary)
AD9148
n
+
+
n
+
–
[−0.4 × f
c
c
0REAL
0IMG
z
z
z
z
–1
–1
–1
–1
+
+
+
–
evaluation tools provide software that allows for the
DAC
Figure 63. Imaginary Filter implementation
c
c
1REAL
z
z
z
1IMG
z
Figure 62. Real Filter implementation
+ 0.5 × signalBW, 0.4 × f
+
+
–1
–1
–1
–1
+
+
+
+
+
–
c
c
2REAL
z
z
z
2IMG
z
–1
+
–1
–1
+
–1
+
+
+
+
+
–
c
c
z
3REAL
z
z
z
3IMG
–1
+
–1
–1
+
–1
+
+
+
+
+
–
c
z
z
c
4REAL
–1
–1
4IMG
+
+
+
+
DAC
Width
3
3
4
4
5
5
7
7
10
10
− 0.5 × signalBW]
c
5REAL
c
5IMG
+
+
+
+
OUTPUT
OUTPUT
DATA
Rev. B | Page 51 of 72
n
n
).
Minimum
100b
−4
0100b
−4
1000b
−8
1000b
−8
10000b
−16
10000b
−16
1000000b
−64
1000000b
−64
1000000000b
−1024
1000000000b
−1024
When there is no interpolation used, the real filter coefficients
can be fixed at (no imaginary coefficients)
C
C
C
C
C
INTERPOLATION FILTERS
The transmit path contains three interpolation filters. Each of
the three interpolation filters provides a 2× increase in output
data rate. The filters can be cascaded to provide 2×, 4×, or 8×
interpolation ratios. Each of the half-band filter stages offers a
different combination of bandwidths and operating modes.
The bandwidth of the three half-band filters with respect to the
data rate at the filter input is as follows:
•
•
•
The usable bandwidth is defined as the frequency over which
the filters have a pass-band ripple of less than ±0.001 dB and an
image rejection of greater than +85 dB. As is discussed in the
Half-Band Filter 1 (HB1) section, the image rejection usually sets
the usable bandwidth of the filter, not the pass-band flatness.
The half-band filters operate in several modes, providing
programmable pass-band center frequencies as well as signal
modulation. The HB1 filter has four modes of operation, and
the HB2 and HB3 filters each have eight modes of operation.
0
1
2
3
4
= 2
= −4
= 10
= −35
= 401
Bandwidth of HB1 = 0.8 × f
Bandwidth of HB2 = 0.5 × f
Bandwidth of HB3 = 0.4 × f
Maximum
011b
3
011b
3
0111b
7
0111b
7
01111b
15
01111b
15
0111111b
63
0111111b
63
0111111111b
1023
0111111111b
1023
;
;
;
;
IN1
IN2
IN3
C
C
C
C
8
7
6
5
= 2
= −4
= 10
= −35
AD9148