Low Noise, High Speed Amplifier

for 16-Bit Systems

AD8021

Rev. F

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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 typical for 5 V supply

Output disable feature, 1.3 mA

Low distortion

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

Small packaging

Available in SOIC-8 and MSOP-8

APPLICATIONS

ADC preamps and drivers

Instrumentation preamps

Active filters

Portable instrumentation

Line receivers

Precision instruments

Ultrasound signal processing

High gain circuits

GENERAL DESCRIPTION

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 @ ±5 V) among

today’s high speed, low noise op amps. The AD8021 operates

over a wide range of supply voltages from ±2.25 V to ±12 V, as

well as from single 5 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.

CONNECTION DIAGRAM

8

7

6

5

1

2

3

4

LOGIC

REFERENCE

–IN

+IN

DISABLE

AD8021

Figure 1. SOIC-8 (R-8) and MSOP-8 (RM-8)

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 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 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 +85°C.

FREQUENCY (Hz)

0.1M

1G

1M

10M

100M

24

21

–6

18

15

12

9

6

3

0

–3

Figure 2. Small Signal Frequency Response