AD8652ARZ Analog Devices Inc, AD8652ARZ Datasheet - Page 14

• Manufacturer Part Number: AD8652ARZ
• Description: IC OPAMP VF CMOS 50MHZ LN 8SOIC
• Manufacturer: Analog Devices Inc
• Series: DigiTrim®r

Specifications of AD8652ARZ

• Slew Rate: 41 V/µs
• Amplifier Type: Voltage Feedback
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Gain Bandwidth Product: 50MHz
• Current - Input Bias: 1pA
• Voltage - Input Offset: 90µV
• Current - Supply: 17.5mA
• Current - Output / Channel: 40mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Op Amp Type: Precision
• No. Of Amplifiers: 2
• Bandwidth: 50MHz
• Supply Voltage Range: 2.7V To 5.5V
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

AD8651/AD8652
APPLICATIONS
THEORY OF OPERATION
The AD865x family consists of voltage feedback, rail-to-rail
input and output precision CMOS amplifiers that operate from
2.7 V to 5.5 V of power supply voltage. These amplifiers use
Analog Devices, Inc. DigiTrim technology to achieve a higher
degree of precision than is available from most CMOS
amplifiers. DigiTrim technology, used in a number of Analog
Devices amplifiers, is a method of trimming the offset voltage of
the amplifier after it has been assembled. The advantage of
post-package trimming is that it corrects any offset voltages
caused by the mechanical stresses of assembly.
The AD865x family is available in standard op amp pinouts,
making DigiTrim completely transparent to the user. The input
stage of the amplifiers is a true rail-to-rail architecture, allowing
the input common-mode voltage range of the op amp to extend
to both positive and negative supply rails. The open-loop gain
of the AD865x with a load of 1 kΩ is typically 115 dB.
The AD865x can be used in any precision op amp application.
The amplifiers do not exhibit phase reversal for common-mode
voltages within the power supply. With voltage noise of
4.5 nV/√Hz and –105 dB distortion for 10 kHz, 2 V p-p signals,
the AD865x is a great choice for high resolution data
acquisition systems. Their low noise, sub-pA input bias current,
precision offset, and high speed make them superb preamps for
fast photodiode applications. The speed and output drive
capabilities of the AD865x also make the amplifiers useful in
video applications.
Rail-to-Rail Output Stage
The voltage swing of the output stage is rail-to-rail and is
achieved by using an NMOS and PMOS transistor pair con-
nected in a common source configuration. The maximum
output voltage swing is proportional to the output current, and
larger currents will limit how close the output voltage can get to
the proximity of the output voltage to the supply rail. This is a
characteristic of all rail-to-rail output amplifiers. With 40 mA of
output current, the output voltage can reach within 5 mV of the
positive and negative rails. At light loads of >100 kΩ, the output
swings within ~1 mV of the supplies.
Rail-to-Rail Input Stage
The input common-mode voltage range of the AD865x extends
to both positive and negative supply voltages. This maximizes
the usable voltage range of the amplifier, an important feature
for single-supply and low voltage applications. This rail-to-rail
input range is achieved by using two input differential pairs, one
NMOS and one PMOS, placed in parallel. The NMOS pair is active
at the upper end of the common-mode voltage range, and the
PMOS pair is active at the lower end of the common-mode range.
Rev. C | Page 14 of 20
The NMOS and PMOS input stages are separately trimmed
using DigiTrim to minimize the offset voltage in both differen-
tial pairs. Both NMOS and PMOS input differential pairs are
active in a 500 mV transition region when the input common-
mode voltage is approximately 1.5 V below the positive supply
voltage. A special design technique improves the input offset
voltage in the transition region that traditionally exhibits a
slight V
ratio is improved within this transition band. Compared to the
Burr Brown OPA350 amplifier, shown in Figure 53, the
AD865x, shown in Figure 54, exhibits much lower offset voltage
shift across the entire input common-mode range, including the
transition region.
–200
–400
–600
–200
–400
–600
600
400
200
600
400
200
OS
Figure 53. Input Offset Distribution over Common-Mode
0
Figure 54. Input Offset Distribution over Common-Mode
0
0
0
variation. As a result, the common-mode rejection
1
1
Input Protection for the AD865x
COMMON-MODE VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
Voltage for the OPA350
2
2
3
3
4
4
5
5
6
6