ad6437 Analog Devices, Inc., ad6437 Datasheet - Page 6

• Manufacturer Part Number: ad6437
• Description: Analog Front End For Adsl
• Manufacturer: Analog Devices, Inc.

This Material Copyrighted By Its Respective Manufacturer
AD6437
RECEIVE CHANNEL
The receive channel consists of the programmable gain ampli-
fier, antialias filter and ADC.
Programmable Gain Amplifier
The input from hybrid and filters is required to drive the PGA
input. This is centered at 2.5 V and has a maximum input
voltage range of 5 V ppd. The input impedance is low, 500
(differential)
to drive a low impedance with low THD up to 1.1 MHz. Addi-
tionally, the multiple feedback topology requires that the ampli-
fier be voltage feedback. Also, the input referred noise should be
as low as possible to preserve the SNR of the channel.
Receive Filters
The antialias filter is set to a 3 dB corner at 4 MHz. If desired,
the filter can be bypassed and an external one used instead.
Analog-to-Digital Converter
The analog-to-digital converter operates to 12-bit resolution
(11-bit linearity), and is clocked at up to 10 MHz.
The filter capacitors shown in Figure 2 are used to decouple the
internal reference voltages of the ADC.
A buffer is required after the filters, at the input to the ADC.
This must be able to drive the 30 pF input capacitance of the
ADC, with the desired bandwidth and distortion properties. A
typical part is the AD8042.
0.1 F
0 LSB
Figure 2. Typical Configuration: Receive Path
ADDR
0.1 F
10 F
30%. This means that the amplifier must be able
Figure 3. Serial Data Format
2
10 F
0.1 F
3
AD6437
REG SELECT
TRANSMITTED LSB FIRST
0.1 F
0.1 F
0.1 F
4
5
15k
2.5V
15k
0.1 F
DATA
15k
AD8042
15k
10
12 MSB
10
–6–
Pg 5
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Table I. Programmable Gain Amplifier Control
Pg 4
0
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Pg 3
x
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Pg 2
x
x
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Pg 1
x
x
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Pg 0
x
x
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Relative
Gain
(dB)
0
0
0
1
2
3
4
5
6
6
6
7
8
9
10
11
12
12
12
13
14
15
16
17
18
18
18
19
20
21
22
23
24
24
24
25
26
27
28
29
30
30
REV. 0