Low Noise, High Speed Amplifier
for 16-Bit Systems
AD8021
CONNECTION DIAGRAM
FEATURES
Low noise
AD8021
LOGIC
REFERENCE
1
2
3
4
8
7
6
5
DISABLE
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
+V
S
–IN
V
+IN
OUT
–V
S
C
COMP
200 MHz (G = −1)
Figure 1. SOIC-8 (R-8) and MSOP-8 (RM-8)
190 MHz (G = −10)
Low power
34 mW or 6.7 mA typical for 5 V supply
Output disable feature, 1.3 mA
Low distortion
−93 dBc second harmonic, fC = 1 MHz
−108 dBc third harmonic, fC = 1 MHz
DC precision
1 mV maximum input offset voltage
0.5 μV/°C input offset voltage drift
Wide supply range, 5 V to 24 V
Low price
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 well-behaved
amplifier that settles to 0.01% in 23 ns for a 1 V step. It has a fast
overload recovery of ±0 ns.
The AD8021 is stable over temperature with low input offset
voltage drift and input bias current drift, 0.± μV/°C and 10 nA/°C,
respectively. The AD8021 is also capable of driving a 7± Ω line
with ±3 V video signals.
Small packaging
Available in SOIC-8 and MSOP-8
The AD8021 is both technically superior and 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 +8±°C.
APPLICATIONS
ADC preamps and drivers
Instrumentation preamps
Active filters
Portable instrumentation
Line receivers
Precision instruments
Ultrasound signal processing
High gain circuits
24
V
= 50mV p-p
OUT
21
18
15
12
9
G = –10, R = 1kΩ, R = 100Ω,
F
G
R
= 100Ω, C = 0pF
C
IN
GENERAL DESCRIPTION
G = –5, R = 1kΩ, R = 200Ω,
The AD8021 is an exceptionally high performance, high speed
voltage feedback amplifier that can be used in 16-bit resolution
systems. It is designed to have both low voltage and low current
noise (2.1 nV/√Hz typical and 2.1 pA/√Hz typical) while operating
at the lowest quiescent supply current (7 mA @ ±± V) among
today’s high speed, low noise op amps. The AD8021 operates
over a wide range of supply voltages from ±2.2± V to ±12 V, as
well as from single ± V supplies, making it ideal for high speed,
low power instruments. An output disable pin allows further
reduction of the quiescent supply current to 1.3 mA.
F
G
R
= 66.5Ω, C = 1.5pF
C
IN
6
G = –2, R = 499Ω, R = 249Ω,
F
G
R
= 63.4Ω, C = 4pF
C
3
IN
0
G = –1, R = 499Ω, R = 499Ω,
F
G
R
= 56.2Ω, C = 7pF
–3
–6
IN
C
0.1M
1M
10M
FREQUENCY (Hz)
100M
1G
Figure 2. Small Signal Frequency Response
Rev. F
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