ANALOG DEVICES ADA4895-2 Service Manual
1 nV/√Hz, Low Power,G≥10 Stable
Preliminary Data Sheet
FEATURES
Low wideband noise
1 nV/√Hz
2.8 pA/√Hz
Low 1/f noise
2.4 nV/√Hz @ 10 Hz
Low distortion: −115 dBc @ 100 kHz, V
Low power: 3 mA/amp
Low input offset voltage: 0.5 mV maximum
High speed
230 MHz, −3 dB bandwidth (G = +10)
500 V/μs slew rate
TBD ns settling time to 0.1%
Rail-to-rail output
Wide supply range: 3 V to 10 V
Disable feature
APPLICATIONS
Low noise preamplifier
Ultrasound amplifiers
PLL loop filters
High performance ADC drivers
DAC buffers
GENERAL DESCRIPTION
The ADA4895-2 is gain 10 stable, low noise, rail-to-rail output,
high speed voltage feedback amplifier having a quiescent
current of 3 mA. With the 1/f noise of 2.4 nV/√Hz at 10 Hz and
a spurious-free dynamic range of −63 dBc at 2 MHz, the
ADA4895-2 is an ideal solution in a variety of applications,
including ultrasound, low noise preamplifiers, and drivers of
high performance ADCs. The Analog Devices, Inc., proprietary
next generation SiGe bipolar process and innovative
architecture enable such high performance amplifiers.
The ADA4895-2 has 1500 MHz Gain bandwidth product,
500 V/μs slew rate, and settle to 0.1% in TBD ns. With a wide
supply voltage range (3 V to 10 V), the ADA4895-2 is ideal
candidates for systems that require high dynamic range, high
gain, precision, and high speed.
The ADA4895-2 is available in 10-lead MSOP package and
itoperates over the extended industrial temperature range of
−40°C to +125°C.
= 2 V p-p
OUT
Rail-to-Rail Output Amplifier
ADA4895-2
FUNCTIONAL BLOCK DIAGRAM
Figure 1. 10-Lead MSOP (ADA4895-2)
8
VS = ±5V
7
6
5
4
3
VOLTAGE NOISE (nV/√Hz)
2
1
0
1 10 100 1k 10k 100k 1M 5M
FREQUENCY (Hz)
Figure 2. Voltage Noise vs. Frequency
Table 1. Other Low Noise Amplifiers
(nV/√Hz)
V
N
Part Number
AD797 0.9 0.9 8 10 to 30
AD8021 5 2.1 490 5 to 24
AD8099 7 0.95 510 5 to 12
AD8045 6 3 1000 3.3 to 12
ADA4897-1 1 1 230 3 to 10
ADA4896-2 1 1 230 3 to 10
ADA4899-1 1.4 1 600 5 to 12
ADA4898-1/
ADA4898-2
@ 1 kHz
0.9 0.9 65 10 to 32
VN (nV/√Hz)
@ 100 kHz
BW (MHz)
Table 2. Complementary ADCs
Part Number Bits Speed (MSPS) Power (mW)
AD7944 14 2.5 15.5
AD7985 16 2.5 15.5
AD7986 18 2 15
09447-102
Supply
Voltage (V)
Rev. PrB
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Fax: 781.461.3113 ©2011 Analog Devices, Inc. All rights reserved.
ADA4895-2 Preliminary Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
±5 V Supply ....................................................................................3
+5 V Supply ....................................................................................5
+3 V Supply ....................................................................................7
Pin Configurations and Function Descriptions ............................9
Typical Performance Characteristics ........................................... 10
Outline Dimensions ....................................................................... 12
Rev. PrB | Page 2 of 12
Preliminary Data Sheet ADA4895-2
SPECIFICATIONS
±5 V SUPPLY
TA = 25°C, G = +10, RL = 1 kΩ to ground, unless otherwise noted.
Table 3.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
–3 dB Bandwidth G = +10, V
G = +10, V
G = +20, V
Bandwidth for 0.1 dB Flatness G = +10, V
Slew Rate G = +10, V
Settling Time to 0.1% G = +10, V
Settling Time to 0.01% G = +10, V
NOISE/HARMONIC PERFORMANCE
Harmonic Distortion (dBc) SFDR fC = 100 kHz, V
f
f
f
= 1 MHz, V
C
= 2 MHz, V
C
= 5 MHz, V
C
Input Voltage Noise f = 10 Hz 2.4 nV/√Hz
f = 100 kHz 1 nV/√Hz
Input Current Noise f = 10 Hz 24 pA/√Hz
f = 100 kHz 2.94 pA/√Hz
0.1 Hz to 10 Hz Noise G = +101, RF = 1 kΩ, RG = 10 Ω 99 nV p-p
DC PERFORMANCE
Input Offset Voltage −500 −28 +500 μV
Input Offset Voltage Drift 0.2 μV/°C
Input Bias Current
−17 −11 −4 μA
Input Bias Current Drift 3 nA/°C
Input Bias Offset Current −0.6 −0.02 +0.6 μA
Open-Loop Gain V
= −4 V to +4 V 100 110 dB
OUT
INPUT CHARACTERISTICS
Input Resistance Common mode/differential 10 M/10 k Ω
Input Capacitance Common mode/differential 3/11 pF
Input Common-Mode Voltage Range −4.9 to +4.1 V
Common-Mode Rejection VCM = −2 V to +2 V −92 −120 dB
OUTPUT CHARACTERISTICS
Output Overdrive Recovery Time VIN = ±5 V, G = +2 81 ns
+Output Voltage Swing RL = 1 kΩ 4.85 4.96 V
−Output Voltage Swing RL = 1 kΩ −4.85 −4.97 V
+Output Voltage Swing RL = 100 Ω 4.5 4.73 V
−Output Voltage Swing RL = 100 Ω −4.5 −4.84 V
Output Current 45 dBc SFDR 80 mA
Short-Circuit Current Sinking/sourcing 135 mA
Capacitive Load Drive 30% overshoot, G = +2 39 pF
POWER SUPPLY
Operating Range 3 to 10 V
Quiescent Current per Amplifier 2.8 3 3.2 mA
DISABLE
Positive Power Supply Rejection +VS = 4 V to 6 V, −VS = −5 V −96 −125 dB
Negative Power Supply Rejection +VS = 5 V, −VS = −4 V to −6 V −96 −121 dB
= 0.2 V p-p 233 MHz
OUT
= 2 V p-p 140 MHz
OUT
= 0.2 V p-p TBD MHz
OUT
= 2 V p-p, RL = 100 Ω 10 MHz
OUT
= 6 V step 500 V/μs
OUT
= 2 V step TBD ns
OUT
= 2 V step TBD ns
OUT
= 2 V p-p −88 dBc
OUT
= 2 V p-p −68 dBc
OUT
= 2 V p-p −63 dBc
OUT
= 2 V p-p −55 dBc
OUT
= −5 V
0.25 mA
Rev. PrB | Page 3 of 12
ADA4895-2 Preliminary Data Sheet
Parameter Conditions Min Typ Max Unit
DISABLE PIN
DISABLE Voltage
Disabled <+VS – 2 V
Input Current
Enabled
Disabled
Switching Speed
Enabled 0.25 μs
Disabled 12 μs
Enabled >+V
DISABLE
DISABLE
= +5 V
= −5 V
−2.5 μA
−80 μA
− 0.5 V
S
Rev. PrB | Page 4 of 12
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