Pin-compatible, lower- speed/resolution versions, Pin configuration, Noise-power ratio (npr) – Rainbow Electronics MAX1215 User Manual
Page 18
MAX1215
1.8V, 12-Bit, 250Msps ADC for
Broadband Applications
18
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Noise-Power Ratio (NPR)
NPR is commonly used to characterize the return path of
cable systems where the signals are typically individual
quadrature amplitude-modulated (QAM) carriers with a
frequency spectrum similar to noise. Numerous such
carriers are operated in a continuous spectrum, generat-
ing a noise-like signal, which covers a relatively broad
bandwidth. To test the MAX1215 for NPR, a “noise-like”
signal is passed through a high-order bandpass filter to
produce an approximately square spectral pedestal of
noise with about the same bandwidth as the signals
being simulated. Following the bandpass filter, the signal
is passed through a narrow band-reject filter to produce
a deep notch at the center of the noise pedestal. Finally,
this signal is applied to the MAX1215 and its digitized
results analyzed. The RMS noise power of the signal
inside the notch is compared with the RMS noise level
outside the notch using an FFT. Note that the NPR test
requires sufficiently long data records to guarantee a
suitable number of samples inside the notch. NPR for the
MAX1215 was determined for 50MHz noise bandwidth
signals, simulating a typical cable signal environment
(see the Typical Operating Characteristics for test details
and results), and with a notch frequency of 28.8MHz.
Pin-Compatible, Lower-
Speed/Resolution Versions
Applications that require lower resolution and/or higher
speed can refer to other family members of the MAX1215.
Adjusting an application to a lower resolution has been
simplified by maintaining an identical pinout for all mem-
bers of this high-speed family. See the Pin-Compatible
Versions table on the first page of this data sheet for a
selection of different resolution and speed grades.
Pin Configuration
58
59
60
61
62
54
55
56
57
63
38
39
40
41
42
43
44
45
46
47
AV
CC
AGND
AV
CC
TOP VIEW
AV
CC
OGND
OV
CC
ORP
ORN
D11P
D11N
D10P
D10N
52
53
D9P
D9N
AGND
AGND
AV
CC
CLKN
CLKP
AV
CC
AGND
OV
CC
OGND
D0N
OV
CC
D1N
D0P
D1P
D6P
D6N
OGND
OV
CC
DCLKP
DCLKN
OV
CC
D5P
D5N
D4P
35
36
37
D4N
D3P
D3N
AGND
INN
INP
AGND
AV
CC
AGND
AGND
AV
CC
AV
CC
AV
CC
AGND
REFADJ
REFIO
AGND
48
D7N
AV
CC
64
AGND
65
66
67
AGND
AGND
AV
CC
68
T/B
23
22
21
20
19
27
26
25
24
18
29
28
32
31
30
D2N
D2P
34
33
49
50
D8N
D7P
EP
51
D8P
11
10
9
8
7
6
5
4
3
2
16
15
14
13
12
1
CLKDIV
17
MAX1215
QFN