AD8039ARZ Analog Devices Inc, AD8039ARZ Datasheet - Page 14

• Manufacturer Part Number: AD8039ARZ
• Description: IC OPAMP VF DUAL LP LN 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD8039ARZ

• Slew Rate: 425 V/µs
• Amplifier Type: Voltage Feedback
• Number Of Circuits: 2
• -3db Bandwidth: 350MHz
• Current - Input Bias: 400pA
• Voltage - Input Offset: 500µV
• Current - Supply: 1mA
• Voltage - Supply, Single/dual (±): 3 V ~ 12 V, ±1.5 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Op Amp Type: Low Power
• No. Of Amplifiers: 2
• Bandwidth: 350MHz
• Supply Voltage Range: 3V To 12V
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

AD8038/AD8039
APPLICATIONS INFORMATION
LOW POWER ADC DRIVER
The AD9203 is a low power (125 mW on a 5 V supply), 40 MSPS
10-bit converter. As such, the low power, high performance
AD8039 is an appropriate amplifier choice to drive it.
In low supply voltage applications, differential analog inputs
are needed to increase the dynamic range of the ADC inputs.
Differential driving can also reduce second and other even-order
distortion products. The AD8039 can be used to make a dc-
coupled, single-ended-to-differential driver for driving these
ADCs. Figure 43 is a schematic of such a circuit for driving the
AD9203, 10-bit, 40 MSPS ADC.
The AD9203 works best when the common-mode voltage at the
input is at the midsupply or 2.5 V. The output stage design of
the AD8039 makes it ideal for driving these types of ADCs.
In this circuit, one of the op amps is configured in the inverting
mode, and the other is in the noninverting mode. However, to
provide better bandwidth matching, each op amp is configured
for a noise gain of +2. The inverting op amp is configured for a
gain of −1, and the noninverting op amp is configured for a gain
of +2. Each has a very similar ac response. The input signal to
the noninverting op amp is divided by 2 to normalize its voltage
level and make it equal to the inverting output.
The outputs of the op amps are centered at 2.5 V, which is the
midsupply level of the ADC. This is accomplished by first taking
the 2.5 V reference output of the ADC and dividing it by 2 with
a pair of 1 kΩ resistors. The resulting 1.25 V is applied to the
positive input of each op amp. This voltage is then multiplied by
the gain of the op amps to provide a 2.5 V level at each output.
0V
V
IN
Figure 43. Schematic to Drive AD9203 with the AD8039
1kΩ
1kΩ
1kΩ
1kΩ
3
2
6
5
+5V
–5V
8
4
1kΩ
1kΩ
1
7
0.1µF
0.1µF
1kΩ
1kΩ
AD8039
10µF
10µF
50Ω
50Ω
0.1µF
10µF
2.5V
VINP
VINN
AD9203
REF
3V
Rev. G | Page 14 of 16
LOW POWER ACTIVE VIDEO FILTER
Some composite video signals derived from a digital source
contain clock feedthrough that can limit picture quality. Active
filters made from op amps can be used in this application, but
they consume 25 mW to 30 mW for each channel. In power-
sensitive applications, this can be too much, requiring the use
of passive filters that can create impedance matching problems
when driving any significant load.
The AD8038 can be used to make an effective low-pass active
filter that consumes one-fifth of the power consumed by an
active filter made from an op amp. Figure 44 shows a circuit
that uses a AD8038 with ±2.5 V supplies to create a three-pole
Sallen-Key filter. This circuit uses a single RC pole in front of a
standard 2-pole active section.
Figure 45 shows the frequency response of this filter. The
response is down 3 dB at 6 MHz; therefore, it passes the video
band with little attenuation. The rejection at 27 MHz is 45 dB,
which provides more than a factor of 100 in suppression of the
clock components at this frequency.
V
IN
R4
49.9Ω
–10
–20
–30
–40
–50
–60
10
200Ω
0
R1
0.1
C1
100pF
499Ω
R2
Figure 44. Low-Pass Filter for Video
Figure 45. Video Filter Response
49.9Ω
R3
680pF
1
FREQUENCY (MHz)
C3
33pF
AD8038
+2.5V
–2.5V
0.1µF
1Ω
10
R
0.1µF
F
10µF
10µF
R5
75Ω
100
V
OUT