AD9761
DIGITAL FILTER SPECIFICATIONS
Parameter
MAXIMUM INPUT CLOCK RATE (f
CLOCK
)
DIGITAL FILTER CHARACTERISTICS
Passband Width
1
: 0.005 dB
Passband Width: 0.01 dB
Passband Width: 0.1 dB
Passband Width: –3 dB
Linear Phase (FIR Implementation)
Stopband Rejection: 0.3 f
CLOCK
to 0.7 f
CLOCK
Group Delay
2
Impulse Response Duration
3
–40 dB
–60 dB
(T
MIN
to T
MAX
, AVDD = +2.7 V to 5.5 V, DVDD = +2.7 V to 5.5 V, I
OUTFS
= 10 mA unless
otherwise noted)
Min
40
0.2010
0.2025
0.2105
0.239
–62.5
32
28
40
Typ
Max
Units
MSPS
f
OUT
/f
CLOCK
f
OUT
/f
CLOCK
f
OUT
/f
CLOCK
f
OUT
/f
CLOCK
dB
Input Clock Cycles
Input Clock Cycles
Input Clock Cycles
NOTES
1
Excludes SINX/X characteristic of DAC.
2
Defined as the number of data clock cycles between impulse input and peak of output response.
3
55 input clock periods from input to I DAC, 56 to Q DAC. Propagation delay is delay from data input to DAC update.
0
Table I. Integer Filter Coefficients for 43-Tap Halfband
FIR Filter
–20
Lower Coefficient
OUTPUT – dBFS
–40
Upper Coefficient
H(43)
H(42)
H(41)
H(40)
H(39)
H(38)
H(37)
H(36)
H(35)
H(34)
H(33)
H(32)
H(31)
H(30)
H(29)
H(28)
H(27)
H(26)
H(25)
H(24)
H(23)
Integer Value
1
0
–3
0
8
0
–16
0
29
0
–50
0
81
0
–131
0
216
0
–400
0
1264
1998
–60
–80
–100
–120
0
0.1
0.2
0.3
0.4
FREQUENCY RESPONSE – DC to f
CLOCK
/2
0.5
Figure 2a. FIR Filter Frequency Response
1
0.9
0.8
0.7
NORMALIZED OUTPUT
0.6
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
0
5
10
15
20
25
TIME – Samples
30
35
40
H(1)
H(2)
H(3)
H(4)
H(5)
H(6)
H(7)
H(8)
H(9)
H(10)
H(11)
H(12)
H(13)
H(14)
H(15)
H(16)
H(17)
H(18)
H(19)
H(20)
H(21)
H(22)
Figure 2b. FIR Filter Impulse Response
–4–
REV. A
AD [ ANALOG DEVICES ]
