DUAL RAIL-TO-RAIL CMOS OPERATIONAL AMPLIFIER
ADVANCED
LINEAR
DEVICES, INC.
ALD2704A/ALD2704B
ALD2704
GENERAL DESCRIPTION
The ALD2704 is a dual monolithic operational amplifier with MOSFET
input that has rail-to-rail input and output voltage ranges. The input
voltage range and output voltage range are very close to the positive and
negative power supply voltages. Typically the input voltage can be
beyond positive power supply voltage V + or the negative power supply
voltage V- by up to 300mV. The output voltage swings to within 60mV of
either positive or negative power supply voltages at rated load.
With high impedance load, the output voltage of the ALD2704 ap-
proaches within 1mV of the power supply rails. This device is designed
as an alternative to the popular J-FET input operational amplifier in
applications where lower operating voltages, such as 9V battery or ±3.25V
to ±6V power supplies are being used. The ALD2704 offers high slew rate
of 5V/µs. It is designed and manufactured with Advanced Linear Devices'
standard enhanced ACMOS silicon gate CMOS process, and it offers low
unit cost and exceptional reliability.
The rail-to-rail input and output feature of the ALD2704 expands signal
voltage range for a given operating supply voltage and allows numerous
analog serial stages to be implemented without losing operating voltage
margin. The output stage is designed to drive up to 10mA into 400pF
capacitive and 1.5KΩ resistive loads at unity gain and up to 4000pF at a
gain of 5. Short circuit protection to either ground or the power supply rails
is at approximately 15mA clamp current. Due to complementary output
stage design, the output can source and sink 10mA into a load with
symmetrical drive and is ideally suited for applications where push-pull
voltage drive is desired.
For each of the operational amplifier, the offset voltage is trimmed on-chip
to eliminate the need for external nulling in many applications. For
precision applications, the output is designed to settle to 0.1% in 2µs. In
large signal buffer applications, the operational amplifier can function as
an ultrahigh input impedance voltage follower /buffer that allows input and
output voltage swings from positive to negative supply voltages. This
feature is intended to greatly simplify systems design and eliminate higher
voltage power supplies in many applications.
FEATURES
• Rail-to-rail input and output voltage ranges
• Symmetrical push-pull output drives
• Output settles to 2mV of supply rails
• 5.0V/µs slew rate
• High capacitive load capability -- up to 4000pF
• No frequency compensation required -- unity
gain stable
• Extremely low input bias currents -- <1.0pA
typical (20pA max.)
• Ideal for high source impedance applications
• High voltage gain -- typically 100V/mV
• Output short circuit protected
• Unity gain bandwidth of 2.1MHz
APPLICATIONS
• Voltage amplifier
• Voltage follower/buffer
• Charge integrator
• Photodiode amplifier
• Data acquisition systems
• High performance portable instruments
• Signal conditioning circuits
• Low leakage amplifiers
• Active filters
• Sample/Hold amplifier
• Picoammeter
• Current to voltage converter
• Coaxial cable driver
• Capacitive sensor amplifier
• Piezoelectric transducer amplifier
PIN CONFIGURATION
1
2
3
4
8
7
6
5
TOP VIEW
DA, PA, SA PACKAGE
OUT
A
-IN
A
+IN
A
V+
-IN
B
+IN
B
V-
OUT
B
Operating Temperature Range*
-55°C to +125°C0°C to +70°C0°C to +70°C
8-Pin 8-Pin 8-Pin
CERDIP Small Outline Plastic Dip
Package Package (SOIC) Package
ALD2704A DA ALD2704A SA ALD2704A PA
ALD2704B DA ALD2704B SA ALD2704B PA
ALD2704 DA ALD2704 SA ALD2704 PA
ORDERING INFORMATION
* Contact factory for industrial temperature range
© 1998 Advanced Linear Devices, Inc. 415 T asman Drive, Sunnyvale, California 94089 -1706 Tel: (408) 747-1 155 Fax: (408) 747-1286 http://www .aldinc.com
ALD2704A/ALD2704B Advanced Linear Devices 2
ALD2704
ABSOLUTE MAXIMUM RATINGS
Supply voltage, V+ referenced to V--0.3V to V++13.2V
Supply voltage, VS referenced to V-±6.6V
Differential input voltage range -0.3V to V+ +0.3V
Power dissipation 600 mW
Operating temperature range PA, SA package 0°C to +70°C
DA package -55°C to +125°C
Storage temperature range -65°C to +150°C
Lead temperature, 10 seconds +260°C
Supply VS±3.25 ±6.0 ±3.25 ±6.0 ±3.25 ±6.0 V Dual Supply
Voltage V+6.5 12.0 6.5 12.0 6.5 12.0 V Single Supply
Input Offset VOS 1.0 2.0 5.0 mV RS ≤ 100KΩ
Voltage 1.5 3.0 6.0 mV 0°C ≤ TA ≤ +70 °C
Input Offset IOS 1.0 15 1.0 15 1.0 15 pA TA = 25°C
Current 240 240 240 pA 0°C ≤ TA ≤ +70°C
Input Bias IB1.0 20 1.0 20 1.0 20 pA TA = 25°C
Current 300 300 300 pA 0°C ≤ TA ≤ +70°C
Input Voltage VIR -5.3 5.3 -5.3 5.3 -5.3 5.3 V
Range
Input RIN 1012 1012 1012 Ω
Resistance
Input Offset TCVOS 555µV/°CR
S ≤ 100KΩ
Voltage Drift
Power Supply PSRR 65 80 65 80 60 80 dB RS ≤ 100KΩ
Rejection Ratio 0°C ≤ TA ≤ +70°C
Common Mode CMRR 65 83 65 83 60 83 dB RS ≤ 100KΩ
Rejection Ratio 0°C ≤ TA ≤ +70°C
Large Signal AV15 28 15 28 10 28 V/mV RL = 100KΩ
Voltage Gain 100 100 100 V/mV RL ≥ 1MΩ
Output VO low -4.96 -4.90 -4.96 -4.90 -4.96 -4.90 RL ≥ 10KΩ
Voltage VO high 4.90 4.95 4.90 4.95 4.90 4.95 V 0°C ≤ TA ≤ +70°C
Range VO low -4.998 -4.99 -4.998 -4.99 -4.998 -4.99 RL = 1MΩ
VO high 4.99 4.998 4.99 4.998 4.99 4.998 V 0°C ≤ TA ≤ +70°C
Output Short ISC 15 15 15 mA
Circuit Current
Supply IS5.0 6.5 5.0 6.5 5.0 6.5 mA VIN = -5V
Current No Load
Power PD65 65 65 mW Both amplifiers, No Load
Dissipation VS = ±5.0V
Input CIN 111pF
Capacitance
Bandwidth BW2.1 2.1 2.1 MHz
Slew Rate SR5.0 5.0 5.0 V/µsA
V
= +1 RL = 2.0KΩ
Rise time tr0.1 0.1 0.1 µsR
L
= 2.0KΩ
Overshoot 15 15 15 % RL = 2.0KΩ
Factor CL = 100pF
OPERATING ELECTRICAL CHARACTERISTICS
TA = 25°C VS = ±5.0V unless otherwise specified
2704A 2704B 2704 Test
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Conditions
ALD2704A/ALD2704B Advanced Linear Devices 3
ALD2704
Maximum Load CL400 400 400 pF Gain = 1
Capacitance 4000 4000 4000 pF Gain = 5
Input Noise en26 26 26 nV/√Hz f =1KHz
Voltage
Input Current in0.6 0.6 0.6 fA/√Hz f =10Hz
Noise
Settling ts5.0 5.0 5.0 µs 0.01%
Time 2.0 2.0 2.0 µs 0.1% AV = 1
RL = 5KΩ CL= 50pF
OPERATING ELECTRICAL CHARACTERISTICS (cont'd)
TA = 25°C VS = ±5.0V unless otherwise specified
2704A 2704B 2704
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions
Input Offset VOS 2.0 4.0 7.0 mV RS ≤ 100KΩ
Voltage
Input Offset IOS 8.0 8.0 8.0 nA
Current
Input Bias IB10.0 10.0 10.0 nA
Current
Power Supply PSRR 60 75 60 75 60 75 dB RS ≤ 100KΩ
Rejection Ratio
Common Mode CMRR 60 83 60 83 60 83 dB RS ≤ 100KΩ
Rejection Ratio
Large Signal AV 10 25 10 25 10 25 V/mV RL = 10KΩ
Voltage Gain
Output Voltage VO low -4.9 -4.8 -4.9 -4.8 -4.9 -4.8
Range VO high 4.8 4.9 4.8 4.9 4.8 4.9 V RL = 10KΩ
VS = ±5.0V -55°C ≤ TA ≤ +125°C unless otherwise specified
2704ADA 2704BDA 2704DA
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions
ALD2704A/ALD2704B Advanced Linear Devices 4
ALD2704
Design & Operating Notes:
1. The ALD2704 CMOS operational amplifier uses a 3 gain stage
architecture and an improved frequency compensation scheme to
achieve large voltage gain, high output driving capability, and better
frequency stability. The ALD2704 is internally compensated for unity
gain stability using a novel scheme. This design produces a clean
single pole roll off in the gain characteristics while providing for more
than 70 degrees of phase margin at the unity gain frequency. A unity
gain buffer using the ALD2704 will typically drive 400pF of external
load capacitance without stability problems. In the inverting unity gain
configuration, it can drive up to 800pF of load capacitance. Compared
to other CMOS operational amplifiers, the ALD2704 is much more
resistant to parasitic oscillations.
2. The ALD2704 has complementary p-channel and n-channel input
differential stages connected in parallel to accomplish rail to rail input
common mode voltage range. With the common mode input voltage
close to the power supplies, one of the two differential stages is
switched off internally. To maintain compatibility with other opera-
tional amplifiers, this switching point has been selected to be about
1.5V above the negative supply voltage. As offset voltage trimming
on the ALD2704 is made when the input voltage is symmetrical to the
supply voltages, this internal switching does not affect a large variety
of applications such as an inverting amplifier or non-inverting amplifier
with a gain greater than 2 (10V operation), where the common mode
voltage does not make excursions below this switching point.
3. The input bias and offset currents are essentially input protection
TYPICAL PERFORMANCE CHARACTERISTICS
diode reverse bias leakage currents, and are typically less than 1pA
at room temperature. This low input bias current assures that the
analog signal from the source will not be distorted by input bias
currents. For applications where source impedance is very high, it
may be necessary to limit noise and hum pickup through proper
shielding.
4. The output stage consists of class AB complementary output drivers,
capable of driving a low resistance load. The output voltage swing is
limited by the drain to source on-resistance of the output transistors as
determined by the bias circuitry, and the value of the load resistor. The
voltage follower configuration, the oscillation and resistant with the
rail- to-rail input and output feature, makes the ALD2704 an effective
analog signal buffer for medium to high source impedance sensors,
transducers, and other circuit networks.
5. The ALD2704 operational amplifier has been designed to provide
static discharge protection. Internally, the design has been carefully
implemented to minimize latch up. However, care must be exercised
when handling the device to avoid strong static fields. In using the
operational amplifier, the user is advised to power up the circuit before,
or simultaneously with, any input voltages applied and to limit input
voltages to not exceed 0.3V of the power supply voltage levels.
Alternatively, a 100KΩ or higher value resistor at the input terminals
will limit input currents to acceptable levels while causing very small
or negligible accuracy effects.
OPEN LOOP VOLTAGE GAIN AS A FUNCTION
OF SUPPLY VOLTAGE AND TEMPERATURE
SUPPLY VOLTAGE (V)
1000
100
10
1
OPEN LOOP VOLTAGE
GAIN (V/mV)
0 ±2 ±4 ±6
RL = 10KΩ
R
L
= 5KΩ
} -55°C
} +25°C
} +125°C
±8
INPUT BIAS CURRENT AS A FUNCTION
OF AMBIENT TEMPERATURE
AMBIENT TEMPERATURE (°C)
1000
100
10
0.1
1.0
INPUT BIAS CURRENT (pA)
100-25 0 75 1255025-50
V
S
= ±5.0V
10000
SUPPLY CURRENT AS A FUNCTION
OF SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (mA)
0±1±2±3±4±5±6
INPUTS GROUNDED
OUTPUT UNLOADED
+80°C
+25°C
T
A
= -55°C
-25°C
±7
1
2
3
4
5
6
7
8
+125°C
COMMON MODE INPUT VOLTAGE RANGE
AS A FUNCTION OF SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
COMMON MODE INPUT
VOLTAGE RANGE (V)
±7
±6
±5
±4
±3
±2±2 ±3 ±4 ±5 ±6 ±7
T
A
= 25°C
ALD2704A/ALD2704B Advanced Linear Devices 5
ALD2704
TYPICAL PERFORMANCE CHARACTERISTICS
OPEN LOOP VOLTAGE AS A FUNCTION
OF FREQUENCY
FREQUENCY (Hz)
1 10 100 1K 10K 1M 10M100K
120
100
80
60
40
20
0
-20
OPEN LOOP VOLTAGE
GAIN (dB)
90
0
45
180
135
PHASE SHIFT IN DEGREES
V
S
= ±5.0V
T
A
= 25°C
LARGE - SIGNAL TRANSIENT
RESPONSE
V
S
= ±5.0V
T
A
= 25°C
R
L
= 1KΩ
C
L
= 50pF
5V/div
5V/div 2µs/div
SMALL - SIGNAL TRANSIENT
RESPONSE
V
S
= ± 5.0V
T
A
= 25°C
R
L
= 1.0KΩ
C
L
= 50pF
100mV/div
50mV/div 1µs/div
OPEN LOOP VOLTAGE GAIN AS A
FUNCTION OF LOAD RESISTANCE
LOAD RESISTANCE (Ω)
1K 10K 1000K100K
1000
100
10
1
OPEN LOOP VOLTAGE
GAIN (V/mV)
V
S
= ±5.0V
T
A
= 25°C
INPUT OFFSET VOLTAGE AS A FUNCTION
OF COMMON MODE INPUT VOLTAGE
COMMON MODE INPUT VOLTAGE (V)
-4 -2 0 +2 +4 +6
15
10
5
0
-5
-10
-15
INPUT OFFSET VOLTAGE (mV)
V
S
= ±5.0V
T
A
= 25ºC
RL = 10KΩ
OUTPUT VOLTAGE SWING AS A
FUNCTION OF SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE SWING (V)
±3
0±1±2±3±4±5±6±7
R
L
= 2KΩ
±6
±5
±4
±2
±7
±25°C ≤ T
A
≤ 125°C
R
L
= 10KΩ
INPUT OFFSET VOLTAGE AS A FUNCTION
OF AMBIENT TEMPERATURE
REPRESENTATIVE UNITS
AMBIENT TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (mV)
-50 -25 0 +25 +50 +75 +100 +125
+4
+5
+3
+1
+2
0
-2
-1
-4
-3
-5
V
S
= ±5.0V
VOLTAGE NOISE DENSITY AS A
FUNCTION OF FREQUENCY
FREQUENCY (Hz)
10 100 1K 10K 100K
150
125
100
75
50
25
0
1000K
VOLTAGE NOISE DENSITY
(nV/ √ Hz)
V
S
= ±5.0V
T
A
= 25°C
ALD2704A/ALD2704B Advanced Linear Devices 6
ALD2704
TYPICAL APPLICATIONS
RAIL-TO-RAIL VOLTAGE FOLLOWER/BUFFER RAIL-TO-RAIL VOLTAGE COMPARATOR
-
+
V
IN
+10V
C
L
R
L
0.1µF
Z
IN
= 10
12
Ω
~
400pF ≥ 1.5KΩ
V
OUT
0 ≤ V
IN
≤ 10V
-
+
50K
0.1µF
10M
V
IN
+12V
+12V
V
OUT
PHOTO DETECTOR CURRENT
TO VOLTAGE CONVERTER
LOW OFFSET SUMMING AMPLIFIER
INPUT 1
INPUT 2
-
+
+5V 0.1µF
0.1µF
-5V
GAIN = 5 C
L
= 4000pF
* Circuit Drives Large Load
Capacitance ≤ 4000pF
10K
10K
50K
V
OUT
WIEN BRIDGE OSCILLATOR (RAIL-TO -RAIL)
SINE WAVE GENERATOR
10K
-
+
10K
10K
+5V
-5V
.01µF
1
2πRC
f = 1.6K Hz
C = .01µFR = 10K
~=
V
OUT
~
LOW PASS FILTER (RFI FILTER)
+
R
F
100K
5K5K
0.02µF
R
1
R
1
C
1
+9V
V
IN
V
OUT
-
Cutoff frequency = π R1C1= 3.2kHz
Gain = 10 Frequency roll-off 20dB/decade
1
PRECISION CHARGE INTEGRATOR
+
1000pF
1MΩ+5V
-5V
V
IN
V
OUT
-
BANDPASS NETWORK
R1 = 10K C1 = 100nF
R2 = 10K C2 = 500pF
+
+5V
-5V
C
1
R
1
C
2
R
2
V
IN
V
OUT
-
Low Frequency
Breakpoint ƒL = 2π R1C1 = 160Hz
High Frequency
Cutoff ƒH = 2π R2 C 2 = 32KHz
1
1
+
-
+5V
-5V
R
F
= 5M
I
PHOTODIODE V
OUT
=
I
X R
F
R
L
≥ 1.5K
