Transcript
Precision, Very Low Noise, Low Input Bias Current Operational Amplifiers AD8671/AD8672/AD8674
Data Sheet FEATURES
PIN CONFIGURATIONS
Very low noise: 2.8 nV/√Hz, 77 nV p-p Wide bandwidth: 10 MHz Low input bias current: 12 nA max Low offset voltage: 75 μV max High open-loop gain: 120 dB min Low supply current: 3 mA typ per amplifier Dual-supply operation: ±5 V to ±15 V Unity-gain stable No phase reversal
NC 1
8
AD8671
NC
V+ TOP VIEW 6 OUT (Not to Scale) V– 4 5 NC
–IN 2
7
NC = NO CONNECT
03718-B-001
+IN 3
Figure 1. 8-Lead SOIC_N (R-8) and 8-Lead MSOP (RM-8)
8
AD8672
V+
OUT B TOP VIEW 6 –IN B (Not to Scale) V– 4 5 +IN B
–IN A 2
APPLICATIONS
7
+IN A 3
PLL filters Filters for GPS Instrumentation Sensors and controls Professional quality audio
03718-B-003
OUT A 1
Figure 2. 8-Lead SOIC-N (R-8) and 8-Lead MSOP (RM-8)
OUT A 1
14
OUT D
–IN A 2
13
–IN D
12
+IN D
+IN A 3
GENERAL DESCRIPTION
AD8674
TOP VIEW 11 V– +IN B 5 (Not to Scale) 10 +IN C
The AD8671/AD8672/AD8674 are very high precision amplifiers featuring very low noise, very low offset voltage and drift, low input bias current, 10 MHz bandwidth, and low power consumption. Outputs are stable with capacitive loads of over 1000 pF. Supply current is less than 3 mA per amplifier at 30 V. The AD8671/AD8672/AD8674’s combination of ultralow noise, high precision, speed, and stability is unmatched. The MSOP version of the AD8671/AD8672 requires only half the board space of comparable amplifiers. Applications for these amplifiers include high quality PLL filters, precision filters, medical and analytical instrumentation, precision power supply controls, ATE, data acquisition, and precision controls as well as professional quality audio.
–IN B 6
9
–IN C
OUT B 7
8
OUT C
03718-B-005
V+ 4
Figure 3. 14-Lead SOIC_N (R-14) and 14-Lead TSSOP (RU-14)
The AD8671, AD8672, and AD8674 are members of a growing series of low noise op amps offered by Analog Devices, Inc. Table 1. Voltage Noise Package Single Dual Quad
0.9 nV AD797
1.1 nV AD8597 AD8599
1.8 nV ADA4004-1 ADA4004-2 ADA4004-4
2.8 nV AD8675 AD8676
3.8 nV AD8671 AD8672 AD8674
The AD8671/AD8672 are specified over the extended industrial temperature range (−40°C to +125°C), and the AD8674 is specified over the industrial temperature range (−40°C to +85°C). The AD8671/AD8672 are available in the 8-lead SOIC and 8-lead MSOP packages. The AD8674 is available in 14-lead SOIC and 14-lead TSSOP packages. Surface-mount devices in MSOP packages are available in tape and reel only.
Rev. F
Document Feedback
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AD8671/AD8672/AD8674
Data Sheet
TABLE OF CONTENTS Specifications..................................................................................... 3
Output Phase Reversal ............................................................... 12
Electrical Characteristics, ±5.0 V ............................................... 3
Total Noise vs. Source Resistance............................................. 12
Electrical Characteristics, ±15 V ................................................ 4
Total Harmonic Distortion (THD) and Noise ....................... 13
Absolute Maximum Ratings ............................................................ 5
Driving Capacitive Loads .......................................................... 13
ESD Caution .................................................................................. 5
GPS Receiver ............................................................................... 14
Typical Performance Characteristics ............................................. 6
Band-Pass Filter .......................................................................... 14
Applications ..................................................................................... 11
PLL Synthesizers and Loop Filters ........................................... 14
Power Dissipation Calculations ................................................ 11
Outline Dimensions ....................................................................... 15
Unity-Gain Follower Applications ........................................... 11
Ordering Guide .......................................................................... 17
REVISION HISTORY 3/13—Rev. E to Rev. F
4/04—Rev. A to Rev. B
Added Figure 7.............................................................................. 6 Updated Outline Dimensions ................................................... 15 Changes to Ordering Guide ...................................................... 17
Changes to Figure 32.................................................................. 11 Changes to Figures 36, 37, and 38 ............................................ 12
6/10—Rev. D to Rev. E
1/04—Rev. 0 to Rev. A
Added Table 1 and Preceding Sentence ..................................... 1
Added AD8672 and AD8674 parts .............................. Universal Changes to Specifications .............................................................3 Deleted Figure 3.............................................................................6 Changes to Figures 7, 8, and 9 .....................................................6 Changes to Figure 37.................................................................. 12 Added new Figure 32 ................................................................. 10
12/09—Rev. C to Rev. D Changes to Features and General Description Sections.......... 1 Changes to Absolute Maximum Ratings Section, Table 3, and Table 4 ................................................................................ 5 Added Power Dissipation Calculations Section ..................... 11 Updated Outline Dimensions ................................................... 15 Changes to Ordering Guide ...................................................... 17 6/05—Rev. B to Rev. C Changes to Figure 6 ...................................................................... 1 Updated Outline Dimensions ................................................... 14 Changes to Ordering Guide ...................................................... 16
Rev. F | Page 2 of 20
Data Sheet
AD8671/AD8672/AD8674
SPECIFICATIONS ELECTRICAL CHARACTERISTICS, ±5.0 V VS = ±5.0 V, VCM = 0 V, TA = 25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift AD8671 AD8672/AD8674 Input Bias Current
Symbol
Conditions
VOS ∆VOS/∆T
–40°C < TA < +125°C –40°C < TA < +125°C
IB +25°C < TA < +125°C –40°C < TA < +125°C
Input Offset Current
IOS +25°C < TA < +125°C –40°C < TA < +125°C
Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance, Common Mode Input Capacitance, Differential Mode Input Resistance, Common Mode Input Resistance, Differential Mode OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Voltage High Output Voltage Low Output Current POWER SUPPLY Power Supply Rejection Ratio AD8671/AD8672 AD8674 Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Current Noise Density Channel Separation AD8672/AD8674
Min
CMRR AVO CINCM CINDM RIN RINDM
VCM = –2.5 V to +2.5 V RL = 2 kΩ, VO = –3 V to +3 V
VOH VOL VOH VOL IOUT
RL = 2 kΩ, –40°C to +125°C RL = 2 kΩ, –40°C to +125°C RL = 600 Ω RL = 600 Ω
PSRR
VS = ±4 V to ±18 V
–12 –20 –40 –12 –20 –40 –2.5 100 1000
+3.8 +3.7
110 106
Typ
Max
Unit
20 30
75 125
µV µV
0.3 0.3 +3 +5 +8 +6 +6 +8
0.5 0.8 +12 +20 +40 +12 +20 +40 +2.5
µV/°C µV/°C nA nA nA nA nA nA V dB V/mV pF pF GΩ MΩ
120 6000 6.25 7.5 3.5 15 +4.0 –3.9 +3.9 –3.8 ±10
130 115 3
ISY
VO = 0 V –40°C < TA < +125°C
SR tS
RL = 2 kΩ To 0.1% (4 V step, G = 1) To 0.01% (4 V step, G = 1)
4 1.4 5.1 10
en p-p en in
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz
77 2.8 0.3
CS
f = 1 kHz f = 10 kHz
–130 –105
GBP
Rev. F | Page 3 of 20
–3.8 –3.7
3.5 4.2
V V V V mA
dB dB mA mA V/µs µs µs MHz
100 3.8
nV p-p nV/√Hz pA/√Hz dB dB
AD8671/AD8672/AD8674
Data Sheet
ELECTRICAL CHARACTERISTICS, ±15 V VS = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted. Table 3. Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift AD8671 AD8672/AD8674 Input Bias Current
Symbol
Conditions
VOS ∆VOS/∆T
–40°C < TA < +125°C –40°C < TA < +125°C
IB +25°C < TA < +125°C –40°C < TA < +125°C
Input Offset Current
IOS +25°C < TA < +125°C –40°C < TA < +125°C
Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance, Common Mode Input Capacitance, Differential Mode Input Resistance, Common Mode Input Resistance, Differential Mode OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Voltage High Output Voltage Low Output Current Short Circuit Current POWER SUPPLY Power Supply Rejection Ratio AD8671/AD8672 AD8674 Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Current Noise Density Channel Separation AD8672/AD8674
Min
CMRR AVO CINCM CINDM RIN RINDM
VCM = –12 V to +12 V RL = 2 kΩ, VO = –10 V to +10 V
VOH VOL VOH VOL IOUT ISC
RL = 2 kΩ, –40°C to +125°C RL = 2 kΩ, –40°C to +125°C RL = 600 Ω RL = 600 Ω
PSRR
VS = ±4 V to ±18 V
–12 –20 –40 –12 –20 –40 –12 100 1000
+13.2 +11
110 106
Typ
Max
Unit
20 30
75 125
µV µV
0.3 0.3 +3 +5 +8 +6 +6 +8
0.5 0.8 +12 +20 +40 +12 +20 +40 +12
µV/°C µV/°C nA nA nA nA nA nA V dB V/mV pF pF GΩ MΩ
120 6000 6.25 7.5 3.5 15 +13.8 –13.8 +12.3 –12.4 ±20 ±30
130 115 3
ISY
VO = 0 V –40°C 1 V) are applied at the positive terminal of amplifiers (such as the OP27, LT1007, OPA227, and AD8671) with back-to-back diodes at the input stage, the use of a resistor in the feedback loop is recommended to avoid having the amplifier load the signal generator. The feedback resistor, RF, should be at least 500 Ω. However, if large values must be used for RF, a small capacitor, CF, should be inserted in parallel with RF to compensate for the pole introduced by the input capacitance and RF. Figure 30 shows the uncompensated output response with a 10 kΩ resistor in the feedback and the compensated response with CF = 15 pF. OUTPUT UNCOMPENSATED
Therefore, the rise above ambient temperature is
OUTPUT COMPENSATED
84 mW × 142°C/W = 12°C
30 V × 4.2 mA × four op amps = 504 mW
Rev. F | Page 11 of 20
CH2 +OVER 7.885%
TIME (100ns/DIV)
Figure 30. Transient Output Response
03718-B-032
For the AD8674 single in the 14-Lead TSSOP package, the thermal resistance, θJA, is 112°C/W. Although θJA is lower than it is for the 8-lead package, the four op amps are powered simultaneously. If the ambient temperature is 50°C and the supply voltages are ±15 V, the power dissipation is
REF1 +OVER 23.23%
VOLTAGE (1V/DIV)
If the ambient temperature is 30°C, the junction temperature is 42°C. The previously mentioned website that details the effect of the junction temperature on reliability has a calculator that requires only the part number and the junction temperature to determine the process technology.
AD8671/AD8672/AD8674
Data Sheet
OUTPUT PHASE REVERSAL
TOTAL NOISE VS. SOURCE RESISTANCE
Phase reversal is a change of polarity in the amplifier transfer function that occurs when the input voltage exceeds the supply voltage. The AD8671/AD8672/AD8674 do not exhibit phase reversal even when the input voltage is 1 V beyond the supplies.
The low input voltage noise of the AD8671/AD8672/AD8674 makes them a great choice for applications with low source resistance. However, because they have low input current noise, they can also be used in circuits with substantial source resistance.
VSY = ±15V
Figure 32 shows the voltage noise, current noise, thermal noise, and total rms noise of the AD8671 as a function of the source resistance.
VOLTAGE (1V/DIV)
VIN
For RS < 475 Ω, the input voltage noise, en, dominates. For 475 Ω < RS < 412 kΩ, thermal noise dominates. For RS > 412 kΩ, the input current noise dominates.
VOUT
TIME (10s/DIV)
Figure 31. Output Phase Reversal
C 100
in
10 en_t
(4kR ST)1/2
1 10
100
en B
A
1k
10k
100k
SOURCE RESISTANCE ()
Figure 32. Noise vs. Source Resistance
Rev. F | Page 12 of 20
1M
03718-B-034
TOTAL NOISE (nV/Hz)
03718-B-033
1000
Data Sheet
AD8671/AD8672/AD8674
TOTAL HARMONIC DISTORTION (THD) AND NOISE
0.1000
VSY = ±15V RL = 2kΩ CL = 1nF VIN = 100mV AV = +1
VOLTAGE (500mV/DIV)
The AD8671/AD8672/AD8674 exhibit low total harmonic distortion (THD) over the entire audio frequency range. This makes them suitable for applications with high closed-loop gains, including audio applications. Figure 33 shows approximately 0.0006% of THD + N in a positive unity gain, the worst-case configuration for distortion.
CH2 +OVER 39.80% CH2 –OVER 39.80%
03718-B-036
VS = ±5V VIN = 2.5V RL = 600Ω
0.0500 0.0200
TIME (10ms/DIV)
Figure 34. AD8671 Capacitive Load Drive
0.0050
RF
0.0020 LT1007
500Ω
0.0010 0.0005
RG
AD8671
500Ω
VCC
CF 220pF
0.0002
RS
50
100
200
500
1k
2k
5k
10k 20k
Hz
03718-B-035
0.0001 20
10Ω
CL 1nF
RL 2kΩ
VIN VEE
Figure 33. Total Harmonic Distortion and Noise
03718-B-037
PERCENTAGE
0.0100
Figure 35. Recommended Capacitive Load Circuit
DRIVING CAPACITIVE LOADS The AD8671/AD8672/AD8674 can drive large capacitive loads without causing instability. However, when configured in unity gain, driving very large loads can cause unwanted ringing or instability. VOLTAGE (100mV/DIV)
CH2 –OVER 6.061%
TIME (10ms/DIV)
Figure 36. Compensated Load Drive
The output response of the circuit is shown in Figure 36.
Rev. F | Page 13 of 20
CH2 +OVER 5.051%
03718-B-038
Figure 34 shows the output of the AD8671 with a capacitive load of 1 nF. If heavier loads are used in low closed-loop gain or unity-gain configurations, it is recommended to use external compensation as shown in the circuit in Figure 35. This technique reduces the overshoot and prevents the op amp from oscillation. The trade-off of this circuit is a reduction in output swing. However, a great added benefit stems from the fact that the input signal and the op amp’s noise are filtered, and thus the overall output noise is kept to a minimum.
VSY = ±15V RL = 2kΩ CL = 1nF CF = 220pF VIN = 100mV AV = +2
AD8671/AD8672/AD8674
Data Sheet ADC
LOW NOISE OP AMP
MIXER
VGA
AD8671
AD831
AD8671
DEMODULATOR
LOW-PASS FILTER
AD630
AD8610
AD10200
AD8369
03718-B-039
BAND-PASS FILTER
CODE GENERATOR
Figure 37. Simplified Block Diagram of a GPS Receiver
GPS RECEIVER
The band-pass response is shown in Figure 39.
GPS receivers require low noise to minimize RF effects. The precision of the AD8671 makes it an excellent choice for such applications. Its very low noise and wide bandwidth make it suitable for band-pass and low-pass filters without the penalty of high power consumption. 200µV/DIV
VS = ±15V
Figure 37 shows a simplified block diagram of a GPS receiver. The next section details the design equations. Filters are useful in many applications; for example, band-pass filters are used in GPS systems, as discussed in the previous section. Figure 38 shows a second-order band-pass KRC filter.
100
1k
10k
100k
2.25kΩ VCC
Figure 39. Band-Pass Response
PLL SYNTHESIZERS AND LOOP FILTERS
C2 C2 1nF
Phase-lock loop filters are used in AM/FM modulation.
1nF
R2 2.25kΩ
RB
18kΩ
RA
10kΩ 03718-B-040
VEE
Figure 38. Band-Pass KRC Filter
The equal component topology yields a center frequency
fo =
2 2πRC
and Q =
Loop filters in PLL design require accuracy and care in their implementation. The AD8671/AD8672/AD8674 are ideal candidates for such filter design; the low offset voltage and low input bias current minimize the output error. In addition to the excellent dc specifications, the AD8671/AD8672/AD8674 have a unique performance at high frequencies; the high open-loop gain and wide bandwidth allow the user to design a filter with a high closed-loop gain if desirable. To optimize the filter design, it is recommended to use small value resistors to minimize the thermal noise. A simple example is shown in Figure 40.
2 4−K
PHASE DETECTOR
where:
K =1+
R1
C1
10kΩ VCC
1nF
CHARGE PUMP
RB RA
VCO
D VEE IN
Figure 40. PLL Filter Simplified Block Diagram
Rev. F | Page 14 of 20
03718-B-042
2.25kΩ VIN
10M
1M
Hz
R3
R1
03718-B-041
BAND-PASS FILTER
Data Sheet
AD8671/AD8672/AD8674
OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890)
8
4.00 (0.1574) 3.80 (0.1497)
5
1
6.20 (0.2441) 5.80 (0.2284)
4
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040)
1.75 (0.0688) 1.35 (0.0532)
0.51 (0.0201) 0.31 (0.0122)
COPLANARITY 0.10 SEATING PLANE
0.50 (0.0196) 0.25 (0.0099)
45°
8° 0° 0.25 (0.0098) 0.17 (0.0067)
1.27 (0.0500) 0.40 (0.0157)
012407-A
COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 41. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches)
3.20 3.00 2.80
8
3.20 3.00 2.80
1
5.15 4.90 4.65
5
4
PIN 1 IDENTIFIER 0.65 BSC 0.95 0.85 0.75
15° MAX 1.10 MAX
0.40 0.25
6° 0°
0.23 0.09
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 42. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters
Rev. F | Page 15 of 20
0.80 0.55 0.40 10-07-2009-B
0.15 0.05 COPLANARITY 0.10
AD8671/AD8672/AD8674
Data Sheet 8.75 (0.3445) 8.55 (0.3366)
4.00 (0.1575) 3.80 (0.1496)
8
14 1
7
6.20 (0.2441) 5.80 (0.2283)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10
0.50 (0.0197) 0.25 (0.0098)
1.75 (0.0689) 1.35 (0.0531) SEATING PLANE
0.51 (0.0201) 0.31 (0.0122)
45°
8° 0° 0.25 (0.0098) 0.17 (0.0067)
1.27 (0.0500) 0.40 (0.0157)
060606-A
COMPLIANT TO JEDEC STANDARDS MS-012-AB CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 43. 14-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches)
5.10 5.00 4.90
14
8
4.50 4.40 4.30
6.40 BSC 1
7
PIN 1 0.65 BSC 1.20 MAX
0.15 0.05 COPLANARITY 0.10
0.30 0.19
0.20 0.09
SEATING PLANE
8° 0°
COMPLIANT TO JEDEC STANDARDS MO-153-AB-1
Figure 44. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters
Rev. F | Page 16 of 20
0.75 0.60 0.45 061908-A
1.05 1.00 0.80
Data Sheet
AD8671/AD8672/AD8674
ORDERING GUIDE Model 1 AD8671ARZ AD8671ARZ-REEL AD8671ARZ-REEL7 AD8671ARMZ AD8671ARMZ-REEL AD8672AR AD8672AR-REEL AD8672AR-REEL7 AD8672ARZ AD8672ARZ-REEL AD8672ARZ-REEL7 AD8672ARMZ AD8672ARMZ-REEL AD8674ARZ AD8674ARZ-REEL AD8674ARZ-REEL7 AD8674ARU AD8674ARUZ AD8674ARUZ-REEL 1
Temperature Range –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C
Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP
Z = RoHS Compliant Part.
Rev. F | Page 17 of 20
Package Option R-8 R-8 R-8 RM-8 RM-8 R-8 R-8 R-8 R-8 R-8 R-8 RM-8 RM-8 R-14 R-14 R-14 RU-14 RU-14 RU-14
Branding
A0V A0V
A0W A0W
AD8671/AD8672/AD8674
Data Sheet
NOTES
Rev. F | Page 18 of 20
Data Sheet
AD8671/AD8672/AD8674
NOTES
Rev. F | Page 19 of 20
AD8671/AD8672/AD8674
Data Sheet
NOTES
©2004–2013 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D03718–0–3/13(F)
Rev. F | Page 20 of 20
