MAX2101 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX2101 Datasheet PDF : 24 Pages
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6-Bit Quadrature Digitizer
BASEBAND
CHANNEL I
REFERENCE
AMPLIFIER
FULL-SCALE/2
–
COMMON
+ MODE
VREF
ADC 6
VREF
(PIN 88)
BANDGAP
REFERENCE
VPTAT
(PIN 97)
BASEBAND
CHANNEL Q
ADC 6
COMMON VREF
MODE
FULL-SCALE/2
REFERENCE
AMPLIFIER
S0-S2
3
SAMPLE-RATE
ADJUST
DIV 6
DATA
BUFFER 6
B/2
DATA
BUFFER 6
B/2
D0I-D5I
DCLK
(PIN 42)
DCLKB
(PIN 41)
MCLK
(PIN 65)
RCLK
(PIN 39)
BINEN
(PIN 56)
D0Q-D5Q
Figure 4. Functional Diagram—MAX2101 ADCs and Supporting Sections
Filter Tuning
The MAX2101 integrates two 5th-order Butterworth low-
pass filters for anti-alias filtering of the baseband sig-
nal. One filter exists for each of the I and Q channels.
The filters’ cutoff frequency is set by driving the FTUNE
pins, pin 77 (I channel) and pin 4 (Q channel). The user
sets the I/Q channel filters independently. Figure 6
shows a typical transfer curve of a filter’s cutoff fre-
quency versus FTUNE voltage.
The MAX2101’s anti-aliasing filtering function provides
superior channel-to-channel matching compared to a
discrete implementation. The filters are realized using a
gyrator topology, which inherently has a strong temper-
ature dependency. The temperature dependency of the
filters must be compensated to achieve a consistent fil-
ter response over ambient temperature. This compen-
sation is easily summed with the user-supplied filter
tune signal, with the techniques discussed for both cur-
rent-drive and voltage-drive implementations later in
this section. Figure 7 shows a typical characteristic of
the FTUNE signal required to provide a constant filter
cutoff frequency over temperature.
V+
CVAR
2pF to 10pF
FROM
PLL
RBUF
FILTER 10k
RBUF
10k
CFLTR
0.1µF
RCHOKE
1k
CVAR
2pF to 10pF
CC
470pF
CSH
3pF to 12pF
CC
470pF
14 TNKB
LRES MAX2101
8nH
17 TNKA
Figure 5. Typical Parallel Resonant Network
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