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PDF ADA4940-2 Data sheet ( Hoja de datos )
| Número de pieza | ADA4940-2 | |
| Descripción | Low Distortion Fully Differential ADC Driver | |
| Fabricantes | Analog Devices | |
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Data Sheet
FEATURES
Small signal bandwidth: 260 MHz
Ultralow power 1.25mA
Extremely low harmonic distortion
−122 dB THD at 50 kHz
−96 dB THD at 1 MHz
Low input voltage noise: 3.9 nV/√Hz
0.35 mV maximum offset voltage
Balanced outputs
Settling time to 0.1%: 34 ns
Rail-to-rail output: −VS + 0.1 V to +VS − 0.1 V
Adjustable output common-mode voltage
Flexible power supplies: 3 V to 7 V (LFCSP)
Disable pin to reduce power consumption
ADA4940-1 is available in LFCSP and SOIC packages
APPLICATIONS
Low power PulSAR®/SAR ADC drivers
Single-ended-to-differential conversion
Differential buffers
Line drivers
Medical imaging
Industrial process controls
Portable electronics
GENERAL DESCRIPTION
The ADA4940-1/ADA4940-2 are low noise, low distortion fully
differential amplifiers with very low power consumption. They
are an ideal choice for driving low power, high resolution, high
performance SAR and sigma-delta (Σ-Δ) analog-to-digital
converters (ADCs) with resolutions up to 16 bits from dc to
1 MHz on only 1.25 mA of quiescent current. The adjustable
level of the output common-mode voltage allows the ADA4940-1/
ADA4940-2 to match the input common-mode voltage of
multiple ADCs. The internal common-mode feedback loop
provides exceptional output balance, as well as suppression of
even-order harmonic distortion products.
With the ADA4940-1/ADA4940-2, differential gain configurations
are easily realized with a simple external feedback network of
four resistors determining the closed-loop gain of the amplifier.
The ADA4940-1/ADA4940-2 are fabricated using Analog Devices,
Inc., SiGe complementary bipolar process, enabling them to
achieve very low levels of distortion with an input voltage noise
of only 3.9 nV/√Hz. The low dc offset and excellent dynamic
performance of the ADA4940-1/ADA4940-2 make them well
suited for a variety of data acquisition and signal processing
applications.
Rev. B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
Ultralow Power, Low Distortion
Fully Differential ADC Driver
ADA4940-1/ADA4940-2
FUNCTIONAL BLOCK DIAGRAMS
–FB 1
+IN 2
–IN 3
+FB 4
ADA4940-1
12 DISABLE
11 –OUT
10 +OUT
9 VOCM
–IN1 1
+FB1 2
+VS1 3
+VS1 4
–FB2 5
+IN2 6
ADA4940-2
18 +OUT1
17 VOCM1
16 –VS2
15 –VS2
14 DISABLE2
13 –OUT2
0
–20
–40
–60
–80
–100
Figure 1.
+DIN
CF
R3 R4
+IN +
33Ω
VOCM
–OUT
ADA4940-1
+OUT
2.7nF
2.7nF
–IN –
33Ω
R1 R2
–DIN
CF
2.5V
IN+ REF VDD
AD7982
IN– GND
–120
–140
–160
0
20k 40k 60k 80k
FREQUENCY (Hz)
Figure 2. ADA4940-1 Driving the AD7982 ADC
100k
The ADA4940-1 is available in a Pb-free, 3 mm × 3 mm, 16-lead
LFCSP, and an 8-lead SOIC. The ADA4940-2 is available in a Pb-
free, 4 mm × 4 mm, 24-lead LFCSP. The pinout is optimized to
facilitate printed circuit board (PCB) layout and minimize
distortion. The ADA4940-1/ADA4940-2 are specified to
operate over the −40°C to +125°C temperature range.
Table 1. Similar Products to the ADA4940-1/ADA4940-2
Product
Isupply Bandwidth Slew Rate Noise
(mA)
(MHz)
(V/µs)
(nV/√Hz)
AD8137
3
110
450 8.25
ADA4932-x 9
560
2800
3.6
ADA4941-1 2.2
31
22 5.1
Table 2. Complementary Products to the ADA4940-1/ADA4940-2
Product
Power Throughput Resolution SNR
(mW) (MSPS)
(Bits)
(dB)
AD7982
7.0 1
18 98
AD7984
10.5 1.333
18
96.5
AD7621 65 3
16 88
AD7623 45 1.333
16
88
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2011–2012 Analog Devices, Inc. All rights reserved.
1 page  
Data Sheet
ADA4940-1/ADA4940-2
VS = 3 V
VOCM = Mid Supply, RF = RG = 1 kΩ, RL, dm = 1 kΩ, TA = 25°C, LFCSP package, unless otherwise noted. TMIN to TMAX = −40°C to +125°C.
(See Figure 61 for the definition of terms.)
+DIN or –DIN to VOUT, dm Performance
Table 6.
Parameter
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth
−3 dB Large Signal Bandwidth
Bandwidth for 0.1 dB Flatness
Slew Rate
Settling Time to 0.1%
Overdrive Recovery Time
NOISE/HARMONIC PERFORMANCE
HD2/HD3
IMD3
Input Voltage Noise
Input Current Noise
Crosstalk
INPUT CHARACTERISTICS
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Bias Current Drift
Input Offset Current
Input Common-Mode Voltage Range
Test Conditions/Comments
VOUT, dm = 0.1 V p-p
VOUT, dm = 0.1 V p-p, G = 2
VOUT, dm = 0.1 V p-p, G = 5
VOUT, dm = 2 V p-p
VOUT, dm = 2 V p-p, G = 2
VOUT, dm = 2 V p-p, G = 5
VOUT, dm = 0.1 V p-p
VOUT, dm = 2 V step
VOUT, dm = 2 V step
G = 2, VIN, dm = 3.6 V p-p, triangle wave
VOUT, dm = 2 V p-p, fC = 50 kHz (HD2/HD3)
VOUT, dm = 2 V p-p, fC = 1 MHz (HD2/HD3)
VOUT,dm = 2 V p-p, f1 = 1.9 MHz, f2 = 2.1 MHz
f = 100 kHz
f = 100 kHz
VOUT, dm = 2 V p-p, fC = 1 MHz
VIP = VIN = VOCM = 1.5 V
TMIN to TMAX
TMIN to TMAX
Input Resistance
Input Capacitance
Common-Mode Rejection Ratio (CMRR)
Open-Loop Gain
OUTPUT CHARACTERISTICS
Output Voltage Swing
Differential
Common mode
ΔVOS, dm/ΔVIN, cm, ∆VIN, cm = ±0.25 V dc
Each single-ended output
Linear Output Current
Output Balance Error
f = 1 MHz, RL, dm = 26 Ω, SFDR = −60 dBc
f = 1 MHz, ΔVOUT, cm/ΔVOUT, dm
Min Typ Max Unit
240 MHz
200 MHz
70 MHz
24 MHz
20 MHz
17 MHz
14 MHz
90 V/µs
37 ns
85 ns
−115/−121
−104/−96
−98
3.9
0.84
−110
dBc
dBc
dBc
nV/√Hz
pA/√Hz
dB
−0.4
−1.6
−500
86
91
±0.06
1.2
−1.1
−4.5
±50
−VS − 0.2 to
+VS − 1.2
33
50
1
114
99
+0.4
+500
mV
µV/°C
µA
nA/°C
nA
V
kΩ
MΩ
pF
dB
dB
−VS + 0.08 to
+VS − 0.08
−VS + 0.04 to
+VS − 0.04
38
−65
−60
V
mA peak
dB
Rev. B | Page 5 of 32
5 Page 
Data Sheet
4
SOIC-1
3 LFCSP-1
2
1
0
LFCSP-2: CH2
–1
–2 LFCSP-2:CH1
–3
–4
–5
–6
–7
–8 VOUT, dm = 0.1V p-p
–9
0.1
1
10
FREQUENCY (MHz)
100
1000
Figure 13. Small Signal Frequency Response for Various Packages
3
2 VOCM = 0V
1
0
VOCM = –1V
–1
–2
VOCM = +1V
–3
–4
–5
–6
–7
–8 VOUT, dm = 0.1V p-p
–9
0.1
1
10
100 1000
FREQUENCY (MHz)
Figure 14. Small Signal Frequency Response at Various VOCM Levels (LFCSP)
4
3 VOCM = 0V
2
1
0
–1 VOCM = –1V
–2
VOCM = +1V
–3
–4
–5
–6
–7
–8 VOUT, dm = 0.1V p-p
–9
0.1 1
10
FREQUENCY (MHz)
100
1000
Figure 15. Small Signal Frequency Response for Various VOCM (SOIC)
ADA4940-1/ADA4940-2
3
LFCSP-1
2 LFCSP-2: CH1
1
LFCSP-2: CH2
SOIC-1
0
–1
–2
–3
–4
–5
–6
–7
–8
VOUT = 2V p-p
–9
1
10
100 1000
FREQUENCY (MHz)
Figure 16. Large Signal Frequency Response for Various Packages
3
2
VOCM = –1V
VOCM = 0V
1 VOCM = +1V
0
–1
–2
–3
–4
–5
–6
–7
–8 VOUT, dm = 2V p-p
–9
0.1
1
10
100 1000
FREQUENCY (MHz)
Figure 17. Large Signal Frequency Response at Various VOCM Levels
4
SOIC: RL = 1kΩ
3
SOIC: RL = 200Ω
2
1
0
–1 LFCSP: RL = 1kΩ
–2
LFCSP: RL = 200Ω
–3
–4
–5
–6
–7
–8 VOUT, dm = 0.1V p-p
–9
0.1 1
10
FREQUENCY (MHz)
100
1000
Figure 18. Small Signal Frequency Response for Various Packages and Loads
Rev. B | Page 11 of 32
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ADA4940-2.PDF ] | |
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