AD648JR Analog Devices Inc, AD648JR Datasheet - Page 10

• Manufacturer Part Number: AD648JR
• Description: IC OPAMP BIFET 1MHZ DUAL 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD648JR

• Mounting Type: Surface Mount
• Rohs Status: RoHS non-compliant
• Amplifier Type: J-FET
• Number Of Circuits: 2
• Slew Rate: 1.8 V/µs
• Gain Bandwidth Product: 1MHz
• Current - Input Bias: 5pA
• Voltage - Input Offset: 750µV
• Current - Supply: 340µA
• Current - Output / Channel: 15mA
• Voltage - Supply, Single/dual (±): ±4.5 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-SOIC (3.9mm Width)
• No. Of Amplifiers: 2
• Bandwidth: 1MHz
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Input Bias Current: 20pA
• Input Offset Voltage Max: 2mV
• Common Mode Ratio: 76
• Output Type: -
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD648
INSTRUMENTATION AMPLIFIER
The AD648J’s maximum input current of 20 pA per amplifier
makes it an excellent building block for the high input impedance
instrumentation amplifier shown in Figure 29. Total current
drain for this circuit is under 600 µA. This configuration is
optimal for conditioning differential voltages from high imped-
ance sources.
The overall gain of the circuit is controlled by R
the following transfer function:
Gains of 1 to 100 can be accommodated with gain nonlinearities
of less than 0.01%. The maximum input current is 30 pA over
V
V
OUT
IN
= 1 +
(R3 + R4)
R
G
Figure 29. Low Power Instrumentation Amplifier
G
, resulting in
–10–
the common-mode range, with a common-mode impedance of
over 1 × 10
for peaking in the gain over frequency which is caused by input
capacitance.
To calibrate this circuit, first adjust trimmer R1 for common-
mode rejection with 10 V dc applied to the input pins. Next,
adjust R2 for zero offset at V
Trim the circuit a second time for optimal
performance.
The –3 dB small signal bandwidth for this low power instru-
mentation amplifier is 700 kHz for a gain of 1 and 10 kHz for a
gain of 100. The typical output slew rate is 1.8 V/µs.
12
Ω. The capacitors C1, C2, C3 and C4 compensate
OUT
with both inputs grounded.
REV. E