ADA4062-2ARZ-R7 Analog Devices Inc, ADA4062-2ARZ-R7 Datasheet - Page 14

• Manufacturer Part Number: ADA4062-2ARZ-R7
• Description: Dual36vLowPwrLowCostJFETInputAmp
• Manufacturer: Analog Devices Inc

Specifications of ADA4062-2ARZ-R7

• Design Resources: 8-Pole Active Low-Pass Filter Optimized for Precision, Low Noise, and High Gain Using AD8622 and ADA4062-2 (CN0127)
• Amplifier Type: J-FET
• Number Of Circuits: 2
• Slew Rate: 3.3 V/µs
• Gain Bandwidth Product: 1.4MHz
• Current - Input Bias: 2pA
• Voltage - Input Offset: 750µV
• Current - Supply: 165µA
• Current - Output / Channel: 20mA
• Voltage - Supply, Single/dual (±): 8 V ~ 36 V, ±4 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADA4062-2
APPLICATIONS INFORMATION
NOTCH FILTER
A notch filter rejects a specific interfering frequency and can
be implemented using a single op amp. Figure 53 shows a 60 Hz
notch filter that uses the twin T network with the ADA4062-2
configured as a voltage follower. The ADA4062-2 works as a buffer
that provides high input resistance and low output impedance.
The low bias current (2 pA typical) and high input resistance
(10 TΩ typical) of the ADA4062-2 enable large resistors and
small capacitors to be used.
Alternatively, different combinations of resistors and capacitors
values can be used to achieve the desired notch frequency.
However, the major drawback to this circuit topology is the
need to ensure that all the resistors and capacitors be closely
matched. If they are not closely matched, the notch frequency
offset and drift cause the circuit to attenuate at a frequency
other than the ideal notch frequency.
Therefore, to achieve the desired performance, 1% or better com-
ponent tolerances are usually required. In addition, a notch filter
requires an op amp with a bandwidth of at least 100 to 200 times
the center frequency. Hence, using the ADA4062-2 with a
bandwidth of 1.4 MHz is excellent for a 60 Hz notch filter.
Figure 54 shows the gain of the notch filter with respect to
frequency. At 60 Hz, the notch filter has about 50 dB atten-
uation of signal.
–10
–20
–30
–40
–50
–60
–70
–80
20
10
0
10
f
R1 = R2 = 2R3
C1 = C2 =
O
IN
=
2π R
Figure 54. Notch Filter: Gain vs. Frequency
804kΩ
1
R1
1
3.3nF
C3
C1
C
2
1
Figure 53. Notch Filter Circuit
R3
402kΩ
C3
6.6nF
3.3nF
FREQUENCY (Hz)
C2
804kΩ
R2
100
+V
–V
1/2
SY
SY
ADA4062-2
V
O
1k
Rev. 0 | Page 14 of 20
HIGH-SIDE SIGNAL CONDITIONING
There are many applications that require the sensing of signals
near the positive rail. The ADA4062-2 can be used in high-side
current sensing applications. Figure 55 shows a high-side signal
conditioning circuit using the ADA4062-2. The ADA4062-2 has
an input common-mode range that includes the positive supply
(−11.5 V ≤ V
a low value resistor, such as the 0.1 Ω shown in Figure 55, is
amplified by a factor of 5 using the ADA4062-2.
MICROPOWER INSTRUMENTATION AMPLIFIER
The ADA4062-2 is a dual amplifier and is perfectly suited for
applications that require lower supply currents. For supply voltages
of ±15 V, the supply current per amplifier is 165 μA typical. The
ADA4062-2 also offers a typical low offset voltage drift of 4 μV/°C
and a very low bias current of 2 pA, which makes it well suited for
instrumentation amplifiers.
Figure 56 shows the classic 2-op-amp instrumentation amplifier
with four resistors using the ADA4062-2. The key to high CMRR
for this instrumentation amplifier are resistors that are well
matched to both the resistive ratio and relative drift. For true
difference amplification, matching of the resistor ratio is very
important, where R3/R4 = R1/R2. Assuming perfectly matched
resistors, the gain of the circuit is 1 + R2/R1, which is approxi-
mately 100. Tighter matching of two op amps in one package,
as is the case with the ADA4062-2, offers a significant boost in
performance over the 3-op-amp configuration. Overall, the circuit
only requires about 330 μA of supply current.
PHASE REVERSAL
Phase reversal occurs in some amplifiers when the input common-
mode voltage range is exceeded. When the voltage driving the
input to these amplifiers exceeds the maximum input common-
mode voltage range, the output of the amplifiers changes polarity.
V
TYPICAL: 0.5mV < │V2 – V1│< 135mV
TYPICAL: –13.8V < V
USE MATCHED RESISTORS
V1
V2
O
1MΩ
Figure 56. Micropower Instrumentation Amplifier
R4
= 100(V2 – V1)
+15V
CM
Figure 55. High-Side Signal Conditioning
100kΩ
500kΩ
≤ +15 V). In the circuit, the voltage drop across
+15V
–15V
1/2
10.1kΩ
R3
ADA4062-2
100kΩ
0.1Ω
O
< +13.5V
10.1kΩ
R1
500kΩ
1/2
–15V
+15V
ADA4062-2
+15V
–15V
1/2
1MΩ
R2
ADA4062-2
R
V
L
O
V
O