AD823ARZ-RL Analog Devices Inc, AD823ARZ-RL Datasheet - Page 14

• Manufacturer Part Number: AD823ARZ-RL
• Description: IC,Operational Amplifier,DUAL,BIPOLAR/JFET,SOP,8PIN,PLASTIC
• Manufacturer: Analog Devices Inc
• Type: General Purpose Amplifierr

Specifications of AD823ARZ-RL

• Amplifier Type: J-FET
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Slew Rate: 25 V/µs
• -3db Bandwidth: 16MHz
• Current - Input Bias: 5pA
• Voltage - Input Offset: 700µV
• Current - Supply: 7mA
• Current - Output / Channel: 17mA
• Voltage - Supply, Single/dual (±): 3 V ~ 36 V, ±1.5 V ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Rail/rail I/o Type: Rail to Rail Output
• Number Of Elements: 2
• Common Mode Rejection Ratio: 60dB
• Input Offset Voltage: 800uV
• Input Bias Current: 25pA
• Single Supply Voltage (typ): 5/9/12/15/18/24/28V
• Dual Supply Voltage (typ): ±3/±5/±9/±12/±15V
• Power Dissipation: 900mW
• Voltage Gain In Db: 93.06dB
• Power Supply Rejection Ratio: 70dB
• Power Supply Requirement: Single/Dual
• Shut Down Feature: No
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 36V
• Dual Supply Voltage (min): ±1.5V
• Dual Supply Voltage (max): ±18V
• Technology: BiFET
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Gain Bandwidth Product: -
• Lead Free Status / Rohs Status: Compliant

AD823
OUTPUT IMPEDANCE
The low frequency open-loop output impedance of the common-
emitter output stage used in this design is approximately 30 kΩ.
Although this is significantly higher than a typical emitter
follower output stage, when it is connected with feedback, the
output impedance is reduced by the open-loop gain of the op
amp. With 109 dB of open-loop gain, the output impedance is
reduced to <0.2 Ω. At higher frequencies, the output impedance
rises as the open-loop gain of the op amp drops; however, the
output also becomes capacitive due to the integrator capacitors
C1 and C2. This prevents the output impedance from ever
becoming excessively high (see Figure 18), which can cause
stability problems when driving capacitive loads. In fact, the AD823
has excellent cap-load drive capability for a high frequency op
amp. Figure 34 shows the AD823 connected as a follower while
driving 470 pF direct capacitive load. Under these conditions,
the phase margin is approximately 20°. If greater phase margin
is desired, a small resistor can be used in series with the output
to decouple the effect of the load capacitance from the op amp
(see Figure 26). In addition, running the part at higher gains
also improves the capacitive load drive capability of the op amp.
Rev. D | Page 14 of 20
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Figure 37. Small Signal Schematic
R1
R1
S1N
S1P
C5
C1
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m2
R2
C2
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OUT