Low Noise, High Speed Amplifier
for 16-Bit Systems
AD8021
FEATURES
Low Noise
2.1 nV/√Hz Input Voltage Noise
2.1 pA/√Hz Input Current Noise
Custom Compensation
Constant Bandwidth from G = –1 to G = –10
High Speed
200 MHz (G = –1)
190 MHz (G = –10)
Low Power
34 mW or 6.7 mA Typ for 5 V Supply
Output Disable Feature, 1.3 mA
Low Distortion
–93 dB Second Harmonic, f
C
= 1 MHz
–108 dB Third Harmonic, f
C
= 1 MHz
DC Precision
1 mV Max Input Offset Voltage
0.5 V/ C Input Offset Voltage Drift
Wide Supply Range, 5 V to 24 V
Low Price
Small Packaging
Available in SOIC-8 and MSOP-8
APPLICATIONS
ADC Preamp and Driver
Instrumentation Preamp
Active Filters
Portable Instrumentation
Line Receivers
Precision Instruments
Ultrasound Signal Processing
High Gain Circuits
CONNECTION DIAGRAM
SOIC-8 (R-8)
MSOP-8 (RM-8)
AD8021
1
2
3
4
8
7
6
5
LOGIC
REFERENCE
–IN
+IN
–V
S
DISABLE
+V
S
V
OUT
C
COMP
The AD8021 allows the user to choose the gain bandwidth
product that best suits the application. With a single capacitor,
the user can compensate the AD8021 for the desired gain with
little trade-off in bandwidth. The AD8021 is a very well behaved
amplifier that settles to 0.01% in 23 ns for a 1 V step. It has a fast
overload recovery of 50 ns.
The AD8021 is stable over temperature with low input offset
voltage drift and input bias current drift, 0.5
µV/°C
and 10 nA/°C,
respectively. The AD8021 is also capable of driving a 75
Ω
line
with
±
3 V video signals.
The AD8021 is not only technically superior, but also priced
considerably less than comparable amps drawing much higher
quiescent current. The AD8021 is a high speed, general-purpose
amplifier, ideal for a wide variety of gain configurations, and can
be used throughout a signal processing chain and in control loops.
The AD8021 is available in both standard 8-lead SOIC and MSOP
packages in the industrial temperature range of –40°C to +85°C.
24
V
OUT
= 50mV p-p
PRODUCT DESCRIPTION
21
18
G = –10, R
F
= 1k , R
G
= 100 ,
R
IN
= 100 , C
C
= 0pF
G = –5, R
F
= 1k , R
G
= 200 ,
R
IN
= 66.5 , C
C
= 1.5pF
The AD8021 is a very high performance, high speed voltage
feedback amplifier that can be used in 16-bit resolution systems.
It is designed to have low voltage and current noise (2.1 nV/√Hz
typ and 2.1 pA/√Hz typ) while operating at the lowest quiescent
supply current (7 mA @
±
5 V) among today’s high speed, low
noise op amps. The AD8021 operates over a wide range of
supply voltages from
±
2.5 V to
±
12 V, as well as from single
5 V supplies, making it ideal for high speed, low power instru-
ments. An output disable pin allows further reduction of the
quiescent supply current to 1.3 mA.
CLOSED-LOOP GAIN – dB
15
12
9
6
3
0
–3
–6
0.1M
1M
10M
FREQUENCY – Hz
100M
1G
G = –2, R
F
= 499 , R
G
= 249 ,
R
IN
= 63.4 , C
C
= 4pF
G = –1, R
F
= 499 , R
G
= 499 ,
R
IN
= 56.2 , C
C
= 7pF
Figure 1. Small Signal Frequency Response
REV. D
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
© 2003 Analog Devices, Inc. All rights reserved.
AD [ ANALOG DEVICES ]
