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Precision, Very Low Noise, Low Input Bias Current Operational Amplifiers
AD8671/AD8672/AD8674
FEATURES
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 V max High open-loop gain: 120 dB min Low supply current: 3 mA per amplifier Dual-supply operation: 5 V to 15 V Unity-gain stable No phase reversal
NC 1 -IN 2 +IN 3
PIN CONFIGURATIONS
8
NC V+
03718-B-001
NC 1 -IN 2 +IN 3
8
NC
AD8671
7
NC = NO CONNECT
NC = NO CONNECT
Figure 1. 8-Lead SOIC_N (R-8)
Figure 2. 8-Lead MSOP (RM-8)
OUT A 1 -IN A 2
8
V+ OUT B
03718-B-003
OUT A 1 -IN A 2 +IN A 3
8
V+
AD8672
7
PLL filters Filters for GPS Instrumentation Sensors and controls Professional quality audio
Figure 3. 8-Lead SOIC-N (R-8)
Figure 4. 8-Lead MSOP (RM-8)
OUT A 1 -IN A 2
14 OUT D 13 -IN D
OUT A 1 -IN A 2 +IN A 3 V+ 4
14 OUT D 13 -IN D
GENERAL DESCRIPTION
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. The AD8671/AD8672/AD8674 are specified over the extended industrial temperature range (-40C to +125C). 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.
+IN A 3 V+ 4
AD8674
12 +IN D
AD8674
12 +IN D
TOP VIEW 11 V- +IN B 5 (Not to Scale) 10 +IN C
03718-B-005
TOP VIEW 11 V- +IN B 5 (Not to Scale) 10 +IN C -IN B 6 OUT B 7
9 8
-IN B 6 OUT B 7
9 8
-IN C OUT C
-IN C OUT C
Figure 5. 14-Lead SOIC_N (R-14)
Figure 6. 14-Lead TSSOP (RU-14)
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or 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. Trademarks and registered trademarks are the property of their respective owners.
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 (c) 2005 Analog Devices, Inc. All rights reserved.
03718-B-006
03718-B-004
APPLICATIONS
+IN A 3
TOP VIEW 6 -IN B (Not to Scale) 5 +IN B V- 4
OUT B TOP VIEW 6 -IN B (Not to Scale) 5 +IN B V- 4
7
AD8672
03718-B-002
TOP VIEW 6 OUT (Not to Scale) V- 4 5 NC
V+ TOP VIEW 6 OUT (Not to Scale) V- 4 5 NC
7
AD8671
AD8671/AD8672/AD8674 TABLE OF CONTENTS
Specifications..................................................................................... 3 Electrical Characteristics, 5.0 V ............................................... 3 Electrical Characteristics, 15 V ................................................ 4 Absolute Maximum Ratings............................................................ 5 ESD CAUTION ............................................................................ 5 Typical Performance Characteristics ............................................. 6 Applications..................................................................................... 11 Unity-Gain Follower Applications ........................................... 11 Output Phase Reversal............................................................... 11 Total Noise vs. Source Resistance............................................. 11 Total Harmonic Distortion (THD) and Noise ....................... 12 Driving Capacitive Loads.......................................................... 12 GPS Receiver............................................................................... 13 Band-Pass Filter.......................................................................... 13 PLL Synthesizers and Loop Filters ........................................... 13 Outline Dimensions ....................................................................... 14 Ordering Guide .......................................................................... 16
REVISION HISTORY
6/05--Rev. B to Rev. C Changes to Figure 6...................................................................... 1 Updated Outline Dimensions ................................................... 14 Changes to Ordering Guide ...................................................... 16 4/04--Rev. A to Rev. B Changes to Figure 32.................................................................. 11 Changes to Figures 36, 37, and 38 ............................................ 12 1/04--Rev. 0 to Rev. A 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
Rev. C | Page 2 of 16
AD8671/AD8672/AD8674 SPECIFICATIONS
ELECTRICAL CHARACTERISTICS, 5.0 V
VS = 5.0 V, VCM = 0 V, TA = 25C, unless otherwise noted. Table 1.
Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift AD8671 AD8672/AD8674 Input Bias Current Symbol VOS VOS/T -40C < TA < +125C -40C < TA < +125C Conditions Min Typ 20 30 0.3 0.3 +3 +5 +8 +6 +6 +8 120 6000 6.25 7.5 3.5 15 +4.0 -3.9 +3.9 -3.8 10 Max 75 125 0.5 0.8 +12 +20 +40 +12 +20 +40 +2.5 Unit V V V/C V/C nA nA nA nA nA nA V dB V/mV pF pF G M V V V V mA
IB +25C < TA < +125C -40C < TA < +125C
Input Offset Current
IOS +25C < TA < +125C -40C < TA < +125C
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
CMRR AVO CINCM CINDM RIN RINDM VOH VOL VOH VOL IOUT PSRR
VCM = -2.5 V to +2.5 V RL = 2 k, VO = -3 V to +3 V
-12 -20 -40 -12 -20 -40 -2.5 100 1000
RL = 2 k, -40C to +125C RL = 2 k, -40C to +125C RL = 600 RL = 600
+3.8 +3.7
-3.8 -3.7
VS = 4 V to 18 V 110 106 130 115 3 dB dB mA mA V/s s s MHz 100 3.8 nV p-p nV/Hz pA/Hz dB dB
ISY
VO = 0 V -40C < TA < +125C RL = 2 k To 0.1% (4 V step, G = 1) To 0.01% (4 V step, G = 1)
3.5 4.2
SR tS GBP en p-p en in CS
4 1.4 5.1 10 77 2.8 0.3 -130 -105
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz f = 1 kHz f = 10 kHz
Rev. C | Page 3 of 16
AD8671/AD8672/AD8674
ELECTRICAL CHARACTERISTICS, 15 V
VS = 15 V, VCM = 0 V, TA = 25C, unless otherwise noted. Table 2.
Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift AD8671 AD8672/AD8674 Input Bias Current Symbol VOS VOS/T -40C < TA < +125C -40C < TA < +125C Conditions Min Typ 20 30 0.3 0.3 +3 +5 +8 +6 +6 +8 120 6000 6.25 7.5 3.5 15 +13.8 -13.8 +12.3 -12.4 20 30 Max 75 125 0.5 0.8 +12 +20 +40 +12 +20 +40 +12 Unit V V V/C V/C nA nA nA nA nA nA V dB V/mV pF pF G M V V V V mA mA
IB +25C < TA < +125C -40C < TA < +125C
Input Offset Current
IOS +25C < TA < +125C -40C < TA < +125C
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
CMRR AVO CINCM CINDM RIN RINDM VOH VOL VOH VOL IOUT ISC PSRR
VCM = -12 V to +12 V RL = 2 k, VO = -10 V to +10 V
-12 -20 -40 -12 -20 -40 -12 100 1000
RL = 2 k, -40C to +125C RL = 2 k, -40C to +125C RL = 600 RL = 600
+13.2 +11
-13.2 -11
VS = 4 V to 18 V 110 106 130 115 3 dB dB mA mA V/s s s MHz 100 3.8 nV p-p nV/Hz pA/Hz dB dB
ISY
VO = 0 V -40C 3.5 4.2
SR tS GBP en p-p en in CS
4 2.2 6.3 10 77 2.8 0.3 -130 -105
0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz f = 1 kHz f = 10 kHz
Rev. C | Page 4 of 16
AD8671/AD8672/AD8674 ABSOLUTE MAXIMUM RATINGS
Table 3. 1
Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range All Packages Operating Temperature Range All Packages Junction Temperature Range All Packages Lead Temperature Range (Soldering, 60 sec)
1
Rating 36 V VS- to VS+ 0.7 V Indefinite -65C to +150C -40C to +125C -65C to +150C 300C
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 4. Package Characteristics
Package Type 8-Lead MSOP (RM) 8-Lead SOIC_N (R) 14-Lead SOIC_N (R) 14-Lead TSSOP (RU)
1
JA 1 190 158 120 180
JC 44 43 36 35
Unit C/W C/W C/W C/W
Absolute maximum ratings apply at 25C, unless otherwise noted. JA is specified for the worst-case conditions, that is., JA is specified for the device soldered in circuit board for surface-mount packages.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. C | Page 5 of 16
AD8671/AD8672/AD8674 TYPICAL PERFORMANCE CHARACTERISTICS
32 VS = 15V
VOLTAGE NOISE DENSITY (nV/Hz)
45 40 35 VS = 5V TA = 25C
28
NUMBER OF AMPLIFIERS
03718-B-007
24 20 16 12 8 4 0
30 25 20 15 10 5 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45
03718-B-010
03718-B-012
0
0
10
20
30
40 50 60 FREQUENCY (Hz)
70
80
90
100
VOS (V)
Figure 7. Voltage Noise Density vs. Frequency
Figure 10. Input Offset Voltage Distribution
31.5 VS = 15V
35 VS = 15V TA = 25C 30
VOLTAGE NOISE DENSITY (nV/ Hz)
27.0 22.5 18.0 13.5
NUMBER OF AMPLIFIERS
03718-B-008
25 20 15 10 5 0
9.0 4.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FREQUENCY (kHz)
-35 -30 -25 -20 -15 -10 -5 0
5 10 15 20 25 30 35 40 45 50 VOS (V)
Figure 8. Voltage Noise Density vs. Frequency
Figure 11. Input Offset Voltage Distribution
17.5 VS = 15V 15.0
16 15 14
VOLTAGE NOISE DENSITY (nV/Hz)
12.5
VOS (V)
13 12 11 10 VS = 5V 9 8
10.0
7.5
5.0
2.5
VS = 15V 7
03718-B-009
0
0
1
2
3
4
5
6
7
8
9
10
6 -40
25
85
125
FREQUENCY (kHz)
TEMPERATURE (C)
Figure 9. Voltage Noise Density vs. Frequency
Figure 12. Input Offset Voltage vs. Temperature
Rev. C | Page 6 of 16
03718-B-011
AD8671/AD8672/AD8674
5.0 VS = 5V 4.5 4.0 3.5 3.0 +IB
OUTPUT VOLTAGE (V)
14.5 RL = 2k 14.0 13.5 13.0 RL = 600 12.5 12.0 11.5 11.0 10.5
03718-B-013
03718-B-016
VS = 15V
IB (nA)
2.5 2.0 -IB 1.5 1.0 0.5 0 -40
25
85
125
10.0 -40
25
85
125
TEMPERATURE (C)
TEMPERATURE (C)
Figure 13. Input Bias Current vs. Temperature
Figure 16. Output Voltage High vs. Temperature
2.5 VS = 15V 2.0 -IB
OUTPUT VOLTAGE (V)
-11.0 VS = 15V -11.5
1.5 1.0
-12.0 -12.5 RL = 600 -13.0
IB (nA)
0.5 +IB 0
-13.5
RL = 2k
-0.5
-14.0
03718-B-014
25
85
125
25
85
125
TEMPERATURE (C)
TEMPERATURE (C)
Figure 14. Input Bias Current vs. Temperature
Figure 17. Output Voltage Low vs. Temperature
4.0 3.8 3.6 3.4 3.2 3.0 VS = 15V 2.8
60 50 40 GAIN VSY = 15V RL = 10k CL = 20pF M = 59
270 225 180 135 90 PHASE 45 0 -45 -90 -135
03718-B-018
30 20 10 0 -10 -20
2.6 VS = 5V
03718-B-015
-30 -40 100k
2.4 -40
-180 1M FREQUENCY (Hz) 10M
25
85
125
TEMPERATURE (C)
Figure 15. Supply Current vs. Temperature
Figure 18. Open-Loop Gain and Phase Shift vs. Frequency
Rev. C | Page 7 of 16
OPEN-LOOP PHASE (dB)
OPEN-LOOP GAIN (dB)
ISY (mA)
03718-B-017
-1.0 -40
-14.5 -40
AD8671/AD8672/AD8674
30000 5V 25000
VSY = 15V VIN = 4V RL = 2k
20000
AVO (V/mV)
15000
15V
10000
5000
03718-B-022
03718-B-019
0 -40
VOLTAGE (1V/DIV)
25
85
125
TIME (100s/DIV)
TEMPERATURE (C)
Figure 19. Open-Loop Gain vs. Temperature
Figure 22. Large Signal Transient Response
50 40 30 AV = 100 VSY = 15V VIN = 10mV RL = CL = 20pF
VSY = 15V VIN = 200mV p-p RL = 2k
VOLTAGE (50mV/DIV)
CLOSED-LOOP GAIN (dB)
20 10
AV = 10
AV = 1 0 -10 -20 -30
-50 1k
10k
100k
1M
10M
100M
03718-B-020
TIME (10s/DIV)
FREQUENCY (Hz)
Figure 20. Closed-Loop Gain vs. Frequency
Figure 23. Small Signal Transient Response
100 90 80 70
60 VS = 15
SMALL SIGNAL OVERSHOOT (%)
50 -OS 40
IMPEDANCE ()
60 50 40 30 20 10 0 100 1k 10k 100k 1M AVO = 100 AVO = 10
30
20
AVO = 1
03718-B-021
10 +OS 0 100
03718-B-024
10M
100M
1k CAPACITANCE (pF)
10k
FREQUENCY (Hz)
Figure 21. Output Impedance vs. Frequency
Figure 24. Small Signal Overshoot vs. Load Capacitance
Rev. C | Page 8 of 16
03718-B-023
-40
AD8671/AD8672/AD8674
160
VS = 15V VIN = 200mV p-p AV = -100 RL = 10k 0V VIN
VSY = 15V 140 120 100
VOLTAGE (200mV/DIV)
PSRR (dB)
80 60 40 20 +PSRR -PSRR
VOUT 0V
03718-B-025
0 -20 -40 10 100 1k 10k 100k 1M 10M
03718-B-028 03718-B-029
03718-B-030
TIME (4s/DIV)
FREQUENCY (Hz)
Figure 25. Positive Overdrive Recovery
Figure 28. PSRR vs. Frequency
135
VIN
VOLTAGE (200mV/DIV)
VSY = 15V VIN = 200mV p-p AV = -100 RL = 10k
VS = 2.5V TO 18V 134 133
PSRR (dB)
03718-B-026
0V
132 131 130 129 128 127 -40
0V VOUT
TIME (4s/DIV)
25
85
125
TEMPERATURE (C)
Figure 26. Negative Overdrive Recovery
Figure 29. PSRR vs. Temperature
160 VSY = 15V 140
VS = 15V
100
CMRR (dB)
80 60 40 20 0
-20 -40 10
03718-B-027
VOLTAGE NOISE (50nV/DIV)
120
100
1k
10k
100k
1M
10M
100M
TIME (1s/DIV)
FREQUENCY (Hz)
Figure 27. CMRR vs. Frequency
Figure 30. 0.1 Hz to 10 Hz Input Voltage Noise
Rev. C | Page 9 of 16
AD8671/AD8672/AD8674
0 VS = 15V, 5V -20
CHANNEL SEPARATION (dB)
-40 -60
-80 -100
-120 -140 100
03718-B-031
1k
1M 10k 100k FREQUENCY (Hz)
10M
100M
Figure 31. Channel Separation
Rev. C | Page 10 of 16
AD8671/AD8672/AD8674 APPLICATIONS
UNITY-GAIN FOLLOWER APPLICATIONS
When large transient pulses (>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 . 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 32 shows the uncompensated output response with a 10 k resistor in the feedback and the compensated response with CF = 15 pF.
OUTPUT UNCOMPENSATED OUTPUT COMPENSATED REF1 +OVER 23.23% CH2 +OVER 7.885%
VIN VSY = 15V
VOLTAGE (1V/DIV)
VOUT
TIME (10s/DIV)
Figure 33. Output Phase Reversal
TOTAL NOISE VS. SOURCE RESISTANCE
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. Figure 34 shows the voltage noise, current noise, thermal noise, and total rms noise of the AD8671 as a function of the source resistance.
03718-B-032
VOLTAGE (1V/DIV)
TIME (100ns/DIV)
Figure 32. Transient Output Response
For RS < 475 , the input voltage noise, en, dominates. For 475 < RS < 412 k, thermal noise dominates. For RS > 412 k, the input current noise dominates.
1000
OUTPUT PHASE REVERSAL
TOTAL NOISE (nV/Hz)
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.
C 100
in
10 en_t A 1 10 100 1k 10k 100k 1M SOURCE RESISTANCE () (4kR ST)1/2 B
03718-B-034
en
Figure 34. Noise vs. Source Resistance
Rev. C | Page 11 of 16
03718-B-033
AD8671/AD8672/AD8674
TOTAL HARMONIC DISTORTION (THD) AND NOISE
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 35 shows approximately 0.0006% of THD + N in a positive unity gain, the worst-case configuration for distortion.
0.1000 0.0500 0.0200 0.0100 VS = 5V VIN = 2.5V RL = 600
VOLTAGE (500mV/DIV)
VSY = 15V RL = 2k CL = 1nF VIN = 100mV AV = +1 CH2 +OVER 39.80% CH2 -OVER 39.80%
TIME (10s/DIV)
PERCENTAGE
0.0050 0.0020 0.0010 0.0005 0.0002
03718-B-035
Figure 36. AD8671 Capacitive Load Drive
RF
LT1007
500
AD8671
RG 500
CF 220pF
VCC
RS 10 VIN VEE
50 100 200 500 Hz 1k 2k 5k 10k 20k
0.0001 20
CL 1nF
Figure 35. Total Harmonic Distortion and Noise
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. Figure 36 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 37. 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. The output response of the circuit is shown in Figure 38.
VOLTAGE (100mV/DIV)
Figure 37. Recommended Capacitive Load Circuit
VSY = 15V RL = 2k CL = 1nF CF = 220pF VIN = 100mV AV = +2
CH2 +OVER 5.051% CH2 -OVER 6.061%
TIME (10s/DIV)
Figure 38. Compensated Load Drive
Rev. C | Page 12 of 16
03718-B-038
03718-B-037
RL 2k
03718-B-036
AD8671/AD8672/AD8674
ADC LOW NOISE OP AMP BAND-PASS FILTER MIXER DEMODULATOR LOW-PASS FILTER VGA
AD8671
AD8671
AD831
AD630
AD8610
AD8369
AD10200
CODE GENERATOR
Figure 39. Simplified Block Diagram of a GPS Receiver
GPS RECEIVER
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. Figure 39 shows a simplified block diagram of a GPS receiver. The next section details the design equations.
The band-pass response is shown in Figure 41.
VS = 15V
BAND-PASS FILTER
Filters are useful in many applications; for example, band-pass filters are used in GPS systems, as discussed in the previous section. Figure 40 shows a second-order band-pass KRC filter.
R3 2.25k VCC
200V/DIV
03718-B-039
100
1k
10k Hz
100k
1M
10M
Figure 41. Band-Pass Response
R1
2.25k VIN C2 1nF
C2 1nF R2 2.25k
PLL SYNTHESIZERS AND LOOP FILTERS
Phase-lock loop filters are used in AM/FM modulation.
RB 18k
VEE RA 10k
03718-B-040
Figure 40. Band-Pass KRC Filter
The equal component topology yields a center frequency
fo =
2 2RC 2 4-K
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 42.
R1 10k VCC C1 1nF
and Q = where:
PHASE DETECTOR
CHARGE PUMP
VCO
K =1+
IN
Figure 42. PLL Filter Simplified Block Diagram
Rev. C | Page 13 of 16
03718-B-042
RB RA
D VEE
03718-B-041
AD8671/AD8672/AD8674 OUTLINE DIMENSIONS
5.00 (0.1968) 4.80 (0.1890)
8 5 4
4.00 (0.1574) 3.80 (0.1497) 1
6.20 (0.2440) 5.80 (0.2284)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040)
1.75 (0.0688) 1.35 (0.0532)
0.50 (0.0196) x 45 0.25 (0.0099)
0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE
8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067)
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 43. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches)
3.00 BSC
8
5
3.00 BSC
1
4.90 BSC
4
PIN 1 0.65 BSC 1.10 MAX 8 0 0.80 0.60 0.40
0.15 0.00 0.38 0.22 COPLANARITY 0.10
0.23 0.08 SEATING PLANE
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 44. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters
Rev. C | Page 14 of 16
AD8671/AD8672/AD8674
8.75 (0.3445) 8.55 (0.3366)
14 1 8 7
4.00 (0.1575) 3.80 (0.1496)
6.20 (0.2441) 5.80 (0.2283)
0.25 (0.0098) 0.10 (0.0039)
1.27 (0.0500) BSC
1.75 (0.0689) 1.35 (0.0531)
0.50 (0.0197) x 45 0.25 (0.0098)
COPLANARITY 0.10
0.51 (0.0201) 0.31 (0.0122)
SEATING PLANE
8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067)
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 45. 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
1 7
6.40 BSC
PIN 1 1.05 1.00 0.80 0.65 BSC 1.20 MAX 0.15 0.05 0.30 0.19 0.20 0.09 8 0 0.75 0.60 0.45
SEATING COPLANARITY PLANE 0.10
COMPLIANT TO JEDEC STANDARDS MO-153-AB-1
Figure 46. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters
Rev. C | Page 15 of 16
AD8671/AD8672/AD8674
ORDERING GUIDE
Model AD8671AR AD8671AR-REEL AD8671AR-REEL7 AD8671ARZ 1 AD8671ARZ-REEL1 AD8671ARZ-REEL71 AD8671ARM-R2 AD8671ARM-REEL AD8671ARMZ-R21 AD8671ARMZ-REEL1 AD8672AR AD8672AR-REEL AD8672AR-REEL7 AD8672ARZ1 AD8672ARZ-REEL1 AD8672ARZ-REEL71 AD8672ARM-R2 AD8672ARM-REEL AD8672ARMZ-R21 AD8672ARMZ-REEL1 AD8674AR AD8674AR-REEL AD8674AR-REEL7 AD8674ARZ1 AD8674ARZ-REEL1 AD8674ARZ-REEL71 AD8674ARU AD8674ARU-REEL AD8674ARUZ1 AD8674ARUZ-REEL1
1
Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C
Package Description 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 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 8-Lead MSOP 8-Lead MSOP 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP
Package Option R-8 R-8 R-8 R-8 R-8 R-8 RM-8 RM-8 RM-8 RM-8 R-8 R-8 R-8 R-8 R-8 R-8 RM-8 RM-8 RM-8 RM-8 R-14 R-14 R-14 R-14 R-14 R-14 RU-14 RU-14 RU-14 RU-14
Branding
BGA BGA A0V A0V
BHA BHA A0W A0W
Z = Pb-free part.
(c) 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D03718-0-6/05(C)
Rev. C | Page 16 of 16

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