AD8132ARM Analog Devices Inc, AD8132ARM Datasheet - Page 27

• Manufacturer Part Number: AD8132ARM
• Description: Amplifier IC
• Manufacturer: Analog Devices Inc

Specifications of AD8132ARM

• Bandwidth: 350MHz
• Slew Rate: 1200V/µs
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Mounting Type: Surface Mount
• Package / Case: 8-uSOIC
• Rohs Status: RoHS non-compliant
• Amplifier Type: Differential
• Number Of Circuits: 1
• Output Type: Differential
• -3db Bandwidth: 360MHz
• Current - Input Bias: 3µA
• Voltage - Input Offset: 1000µV
• Current - Supply: 12mA
• Current - Output / Channel: 70mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 11 V, ±1.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Any imbalance in the differential drive signal appears as a
common-mode signal on the cable. This is the equivalent of
a single wire that is driven with the common-mode signal. In
this case, the wire acts as an antenna and radiates. Therefore, to
minimize radiation when driving differential twisted pair cables,
make sure the differential drive signal is well balanced.
The common-mode feedback loop in the AD8132 helps to
minimize the amount of common-mode voltage at the output
and can, therefore, be used to create a well-balanced differential
line driver. Figure 74 shows an application that uses an AD8132
as a balanced line driver and an
configured for unity gain. This circuit was operated with 10 meters
of Category 5 cable.
TRANSMIT EQUALIZER
Any length of transmission line attenuates the signals it carries.
This effect is worse at higher frequencies than at lower frequencies.
One way to compensate for this is to provide an equalizer circuit
that boosts the higher frequencies in the transmitter circuit, so
that at the receive end of the cable, the attenuation effects are
diminished.
By lowering the impedance of the R
network at a higher frequency, the gain can be increased at a
high frequency. Figure 75 shows the gain of a two-line driver
that has its R
of this is shown in the frequency response plot of Figure 76.
V
IN
G
resistors shunted by 10 pF capacitors. The effect
24.9Ω
49.9Ω
Figure 75. Frequency Boost Circuit
249Ω
249Ω
10pF
10pF
SOURCE
50Ω
499Ω
499Ω
AD830
G
component of the feedback
49.9Ω
49.9Ω
49.9Ω
10µF
Figure 74. Balanced Line Driver and Receiver Using AD8132 and AD830
as a differential receiver
100Ω
0.1µF
+
499Ω
523Ω
0.1µF
V
OUT
–5V
+5V
AD8132
1kΩ
1kΩ
0.1µF
49.9Ω
Rev. I | Page 27 of 32
49.9Ω
+
10µF
TWISTED
PAIR
LOW-PASS DIFFERENTIAL FILTER
Similar to an op amp, various types of active filters can be
created with the AD8132. These can have single-ended inputs
and differential outputs that can provide an antialias function
when driving a differential ADC.
Figure 77 is a schematic of a low-pass, multiple feedback filter.
The active section contains two poles, and an additional pole
is added at the output. The filter was designed to have a −3 dB
frequency of 1 MHz.
V
IN
10µF
–10
–20
–30
–40
–50
–60
–70
–80
20
10
0
24.9Ω
100Ω
Figure 76. Frequency Response for Transmit Boost Circuit
+
1
49.9Ω
1
2
3
4
Figure 77. 1 MHz, 3-Pole Differential Output,
2kΩ
2kΩ
0.1µF
AD830
100pF
100pF
Low-Pass, Multiple Feedback Filter
+5V
–5V
5
0.1µF
10
FREQUENCY (MHz)
7
2.15kΩ
2.15kΩ
953Ω
953Ω
+
10µF
V
OUT
33pF
33pF
100
549Ω
549Ω
200pF
200pF
AD8132
1000
V
OUT