ANALOG DEVICES AD8672

Precision, Very Low Noise, Low Input Bias Current Operational Amplifiers AD8671/AD8672/AD8674 FEATURES PIN CONFIGURATIONS Very low noise: 2.8 nV/√Hz, 77 nV p-p NC 1 8 NC NC 1 8 NC Wide bandwidth: 10 MHz AD8671 AD8671 –IN 2 7 V+ –IN 2 7 V+ TOP VIEW TOP VIEW Low input bias current: 12 nA max +IN 3 6 OUT +IN 3 6 OUT (Not to Scale) (Not to Scale) V– 4 5 NC V– 4 5 NC Low offset voltage: 75 μV max High open-loop gain: 120 dB min NC = NO CONNECT NC = NO CONNECT Low supply current: 3 mA typ per amplifier Figure 1. 8-Lead SOIC_N (R-8) Figure 2. 8-Lead MSOP (RM-8) Dual-supply operation: ±5 V to ±15 V Unity-gain stable No phase reversal OUT A 1 8 V+ OUT A 1 8 V+ AD8672 AD8672 –IN A 2 7 OUT B –IN A 2 7 OUT B TOP VIEW TOP VIEW +IN A 3 6 –IN B +IN A 3 6 –IN B APPLICATIONS (Not to Scale) (Not to Scale) V– 4 5 +IN B V– 4 5 +IN B PLL filters Filters for GPS Figure 3. 8-Lead SOIC-N (R-8) Figure 4. 8-Lead MSOP (RM-8) Instrumentation Sensors and controls Professional quality audio OUT A 1 14 OUT D OUT A 1 14 OUT D –IN A 2 13 –IN D –IN A 2 13 –IN D +IN A 3 12 +IN D +IN A 3 12 +IN D AD8674 AD8674 GENERAL DESCRIPTION V+ 4 11 V– V+ 4 11 V– TOP VIEW TOP VIEW (Not to Scale) (Not to Scale) The AD8671/AD8672/AD8674 are very high precision amplifiers +IN B 5 10 +IN C +IN B 5 10 +IN C –IN B 6 9 –IN C –IN B 6 9 –IN C featuring very low noise, very low offset voltage and drift, low OUT B 7 8 OUT C OUT B 7 8 OUT C input bias current, 10 MHz bandwidth, and low power consumption. Outputs are stable with capacitive loads of over Figure 5. 14-Lead SOIC_N (R-14) Figure 6. 14-Lead TSSOP (RU-14) 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 The AD8671, AD8672, and AD8674 are members of a growing space of comparable amplifiers. series of low noise op amps offered by Analog Devices, Inc. Table 1. Voltage Noise Applications for these amplifiers include high quality PLL Package 0.9 nV 1.1 nV 1.8 nV 2.8 nV 3.8 nV filters, precision filters, medical and analytical instrumentation, Single AD797 AD8597 ADA4004-1 AD8675 AD8671 precision power supply controls, ATE, data acquisition, and Dual AD8599 ADA4004-2 AD8676 AD8672 precision controls as well as professional quality audio. Quad ADA4004-4 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. E 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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2004–2010 Analog Devices, Inc. All rights reserved. 03718-B-001 03718-B-003 03718-B-005 03718-B-002 03718-B-006 03718-B-004 AD8671/AD8672/AD8674 TABLE OF CONTENTS Specif ica t ions ..................................................................................... 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 6/10—Rev. D to Rev. E 4/04—Rev. A to Rev. B Added Table 1 and Preceding Sentence ..................................... 1 Changes to Figure 32 .................................................................. 11 Changes to Figures 36, 37, and 38 ............................................ 12 12/09—Rev. C to Rev. D Changes to Features and General Description Sections .......... 1 1/04—Rev. 0 to Rev. A Changes to Absolute Maximum Ratings Section, Table 3, and Table 4 ................................................................................ 5 Added AD8672 and AD8674 parts .............................. Universal Added Power Dissipation Calculations Section ..................... 11 Changes to Specifications ............................................................. 3 Updated Outline Dimensions ................................................... 15 Deleted Figure 3 ............................................................................. 6 Changes to Ordering Guide ...................................................... 17 Changes to Figures 7, 8, and 9 ..................................................... 6 Changes to Figure 37 .................................................................. 12 Added new Figure 32 ................................................................. 10 6/05—Rev. B to Rev. C Changes to Figure 6 ...................................................................... 1 Updated Outline Dimensions ................................................... 14 Changes to Ordering Guide ...................................................... 16 Rev. E | Page 2 of 20 AD8671/AD8672/AD8674 SPECIFICATIONS ELECTRICAL CHARACTERISTICS, ±5.0 V V = ±5.0 V, V = 0 V, T = 25°C, unless otherwise noted. S CM A Table 2. Parameter Symbol Conditions Min Typ Max Unit INPUT CHARACTERISTICS Offset Voltage V 20 75 μV OS –40°C < T < +125°C 30 125 μV A Offset Voltage Drift ∆V /∆T –40°C < T < +125°C OS A AD8671 0.3 0.5 μV/°C AD8672/AD8674 0.3 0.8 μV/°C Input Bias Current IB –12 +3 +12 nA +25°C < T < +125°C –20 +5 +20 nA A –40°C < T < +125°C –40 +8 +40 nA A Input Offset Current I –12 +6 +12 nA OS +25°C < TA < +125°C –20 +6 +20 nA –40°C < TA < +125°C –40 +8 +40 nA Input Voltage Range –2.5 +2.5 V Common-Mode Rejection Ratio CMRR V = –2.5 V to +2.5 V 100 120 dB CM Large Signal Voltage Gain A R = 2 kΩ, V = –3 V to +3 V 1000 6000 V/mV VO L O Input Capacitance, Common Mode CINCM 6.25 pF Input Capacitance, Differential Mode CINDM 7.5 pF Input Resistance, Common Mode RIN 3.5 GΩ Input Resistance, Differential Mode R 15 MΩ INDM OUTPUT CHARACTERISTICS Output Voltage High VOH RL = 2 kΩ, –40°C to +125°C +3.8 +4.0 V Output Voltage Low V R = 2 kΩ, –40°C to +125°C –3.9 –3.8 V OL L Output Voltage High V R = 600 Ω +3.7 +3.9 V OH L Output Voltage Low V R = 600 Ω –3.8 –3.7 V OL L Output Current IOUT ±10 mA POWER SUPPLY Power Supply Rejection Ratio PSRR VS = ±4 V to ±18 V AD8671/AD8672 110 130 dB AD8674 106 115 dB Supply Current/Amplifier I V = 0 V 3 3.5 mA SY O –40°C < T < +125°C 4.2 mA A DYNAMIC PERFORMANCE Slew Rate SR R = 2 kΩ 4 V/μs L Settling Time t To 0.1% (4 V step, G = 1) 1.4 μs S To 0.01% (4 V step, G = 1) 5.1 μs Gain Bandwidth Product GBP 10 MHz NOISE PERFORMANCE Peak-to-Peak Noise en p-p 0.1 Hz to 10 Hz 77 100 nV p-p Voltage Noise Density en f = 1 kHz 2.8 3.8 nV/√Hz Current Noise Density in f = 1 kHz 0.3 pA/√Hz Channel Separation AD8672/AD8674 C f = 1 kHz –130 dB S f = 10 kHz –105 dB Rev. E | Page 3 of 20 AD8671/AD8672/AD8674 ELECTRICAL CHARACTERISTICS, ±15 V VS = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted. Table 3. Parameter Symbol Conditions Min Typ Max Unit INPUT CHARACTERISTICS Offset Voltage VOS 20 75 μV –40°C < TA < +125°C 30 125 μV Offset Voltage Drift ∆VOS/∆T –40°C < TA < +125°C AD8671 0.3 0.5 μV/°C AD8672/AD8674 0.3 0.8 μV/°C Input Bias Current IB –12 +3 +12 nA +25°C < TA < +125°C –20 +5 +20 nA –40°C < TA < +125°C –40 +8 +40 nA Input Offset Current I –12 +6 +12 nA OS +25°C < T < +125°C –20 +6 +20 nA A –40°C < T < +125°C –40 +8 +40 nA A Input Voltage Range –12 +12 V Common-Mode Rejection Ratio CMRR VCM = –12 V to +12 V 100 120 dB Large Signal Voltage Gain AVO RL = 2 kΩ, VO = –10 V to +10 V 1000 6000 V/mV Input Capacitance, Common Mode C 6.25 pF INCM Input Capacitance, Differential Mode C 7.5 pF INDM Input Resistance, Common Mode RIN 3.5 GΩ Input Resistance, Differential Mode RINDM 15 MΩ OUTPUT CHARACTERISTICS Output Voltage High VOH RL = 2 kΩ, –40°C to +125°C +13.2 +13.8 V Output Voltage Low VOL RL = 2 kΩ, –40°C to +125°C –13.8 –13.2 V Output Voltage High VOH RL = 600 Ω +11 +12.3 V Output Voltage Low V R = 600 Ω –12.4 –11 V OL L Output Current I ±20 mA OUT Short Circuit Current I ±30 mA SC POWER SUPPLY Power Supply Rejection Ratio PSRR V = ±4 V to ±18 V S AD8671/AD8672 110 130 dB AD8674 106 115 dB Supply Current/Amplifier ISY VO = 0 V 3 3.5 mA –40°C 1 V) are applied at the positive http://www.analog.com/en/quality-and-reliability/reliability- terminal of amplifiers (such as the OP27, LT1007, OPA227, and data/content/index.html AD8671) with back-to-back diodes at the input stage, the use of a resistor in the feedback loop is recommended to avoid having MTTF and FIT calculations can be done based on the junction the amplifier load the signal generator. The feedback resistor, temperature and IC process. Use the following equation to RF, should be at least 500 Ω. However, if large values must be determine the junction temperature: used for R , a small capacitor, C , should be inserted in parallel F F with R to compensate for the pole introduced by the input F TJ = TA + PD × θJA capacitance and R . F For the AD8671 single in the 8-lead MSOP package, the thermal Figure 32 shows the uncompensated output response with a resistance, θ , is 142°C/W. If the ambient temperature is 30°C JA 10 kΩ resistor in the feedback and the compensated response and the supply voltages are ±12 V, the power dissipation is with CF = 15 pF. 24 V × 3.5 mA = 84 mW OUTPUT UNCOMPENSATED Therefore, the rise above ambient temperature is OUTPUT COMPENSATED 84 mW × 142°C/W = 12°C REF1 +OVER 23.23% If the ambient temperature is 30°C, the junction temperature is CH2 +OVER 42°C. The previously mentioned website that details the effect 7.885% of the junction temperature on reliability has a calculator that requires only the part number and the junction temperature to determine the process technology. 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 TIME (100ns/DIV) the ambient temperature is 50°C and the supply voltages are ±15 V, Figure 32. Transient Output Response the power dissipation is 30 V × 4.2 mA × four op amps = 504 mW Rev. E | Page 11 of 20 VOLTAGE (1V/DIV) 03718-B-032 AD8671/AD8672/AD8674 TOTAL NOISE VS. SOURCE RESISTANCE OUTPUT PHASE REVERSAL The low input voltage noise of the AD8671/AD8672/AD8674 Phase reversal is a change of polarity in the amplifier transfer makes them a great choice for applications with low source function that occurs when the input voltage exceeds the supply resistance. However, because they have low input current noise, voltage. The AD8671/AD8672/AD8674 do not exhibit phase they can also be used in circuits with substantial source reversal even when the input voltage is 1 V beyond the supplies. resistance. V = ±15V SY Figure 34 shows the voltage noise, current noise, thermal noise, and total rms noise of the AD8671 as a function of the source V IN resistance. 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. V OUT 1000 C 100 TIME (10μs/DIV) i Figure 33. Output Phase Reversal n 10 e 1/2 n_t (4kR T) S e n A B 1 10 100 1k 10k 100k 1M SOURCE RESISTANCE (Ω) Figure 34. Noise vs. Source Resistance Rev. E | Page 12 of 20 VOLTAGE (1V/DIV) 03718-B-033 TOTAL NOISE (nV/√Hz) 03718-B-034 AD8671/AD8672/AD8674 TOTAL HARMONIC DISTORTION (THD) AND NOISE V = ±15V SY R = 2kΩ The AD8671/AD8672/AD8674 exhibit low total harmonic L C = 1nF L distortion (THD) over the entire audio frequency range. This V = 100mV IN A = +1 V makes them suitable for applications with high closed-loop CH2 +OVER 39.80% gains, including audio applications. Figure 35 shows approximately 0.0006% of THD + N in a positive unity gain, the CH2 –OVER 39.80% worst-case configuration for distortion. 0.1000 V = ±5V S 0.0500 V = 2.5V IN R = 600Ω L 0.0200 TIME (10μs/DIV) 0.0100 Figure 36. AD8671 Capacitive Load Drive 0.0050 R 0.0020 F LT1007 500Ω 0.0010 V CC C R G F 0.0005 AD8671 500Ω 220pF 0.0002 R S 10Ω 0.0001 C L 20 50 100 200 500 1k 2k 5k 10k 20k R L 1nF Hz 2kΩ V IN V EE Figure 35. Total Harmonic Distortion and Noise Figure 37. Recommended Capacitive Load Circuit DRIVING CAPACITIVE LOADS The AD8671/AD8672/AD8674 can drive large capacitive loads V = ±15V SY without causing instability. However, when configured in unity R = 2kΩ L C = 1nF gain, driving very large loads can cause unwanted ringing or L C = 220pF F instability. V = 100mV CH2 +OVER IN A = +2 5.051% V Figure 36 shows the output of the AD8671 with a capacitive CH2 –OVER 6.061% 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 TIME (10μs/DIV) overall output noise is kept to a minimum. Figure 38. Compensated Load Drive The output response of the circuit is shown in Figure 38. Rev. E | Page 13 of 20 PERCENTAGE 03718-B-035 VOLTAGE (500mV/DIV) VOLTAGE (100mV/DIV) 03718-B-038 03718-B-037 03718-B-036 AD8671/AD8672/AD8674 ADC LOW NOISE OP AMP MIXER VGA DEMODULATOR LOW-PASS FILTER BAND-PASS FILTER AD630 AD8610 AD8369 AD10200 AD8671 AD831 AD8671 CODE GENERATOR Figure 39. Simplified Block Diagram of a GPS Receiver GPS RECEIVER The band-pass response is shown in Figure 41. GPS receivers require low noise to minimize RF effects. The V = ±15V S 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. 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. 100 1k 10k 100k 1M 10M R3 Hz 2.25kΩ Figure 41. Band-Pass Response V CC PLL SYNTHESIZERS AND LOOP FILTERS C2 R1 2.25kΩ Phase-lock loop filters are used in AM/FM modulation. 1nF C2 V R2 IN 1nF 2.25kΩ R 18kΩ B Loop filters in PLL design require accuracy and care in their implementation. The AD8671/AD8672/AD8674 are ideal V EE candidates for such filter design; the low offset voltage and low R 10kΩ input bias current minimize the output error. In addition to the A 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 Figure 40. Band-Pass KRC Filter high closed-loop gain if desirable. To optimize the filter design, The equal component topology yields a center frequency it is recommended to use small value resistors to minimize the thermal noise. A simple example is shown in Figure 42. 2 fo= C1 R1 2πRC 10kΩ 1nF V CC 2 and Q= 4−K PHASE CHARGE DETECTOR PUMP VCO where: D R B K=1 + V R EE A IN Figure 42. PLL Filter Simplified Block Diagram Rev. E | Page 14 of 20 03718-B-040 200μV/DIV 03718-B-039 03718-B-042 03718-B-041 AD8671/AD8672/AD8674 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 85 6.20 (0.2441) 4.00 (0.1574) 1 5.80 (0.2284) 3.80 (0.1497) 4 0.50 (0.0196) 1.27 (0.0500) 45° BSC 1.75 (0.0688) 0.25 (0.0099) 1.35 (0.0532) 0.25 (0.0098) 8° 0.10 (0.0040) 0° 0.51 (0.0201) COPLANARITY 1.27 (0.0500) 0.10 0.31 (0.0122) 0.25 (0.0098) SEATING 0.40 (0.0157) PLANE 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) 3.20 3.00 2.80 8 5 5.15 3.20 4.90 3.00 4.65 1 2.80 4 PIN 1 IDENTIFIER 0.65 BSC 0.95 15° MAX 0.85 1.10 MAX 0.75 0.80 0.15 0.23 6° 0.55 0.40 0.05 0.09 0° 0.40 0.25 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 44. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters Rev. E | Page 15 of 20 100709-B 012407-A AD8671/AD8672/AD8674 8.75 (0.3445) 8.55 (0.3366) 8 14 6.20 (0.2441) 4.00 (0.1575) 1 5.80 (0.2283) 3.80 (0.1496) 7 1.27 (0.0500) 0.50 (0.0197) 45° BSC 0.25 (0.0098) 1.75 (0.0689) 0.25 (0.0098) 1.35 (0.0531) 8° 0.10 (0.0039) 0° COPLANARITY SEATING 1.27 (0.0500) 0.51 (0.0201) 0.10 PLANE 0.25 (0.0098) 0.40 (0.0157) 0.31 (0.0122) 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 6.40 4.40 BSC 4.30 1 7 PIN 1 0.65 BSC 1.05 1.20 1.00 0.20 MAX 0.80 0.09 0.75 0.15 8° 0.60 SEATING 0° 0.05 0.45 0.30 PLANE COPLANARITY 0.19 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. E | Page 16 of 20 061908-A 060606-A AD8671/AD8672/AD8674 ORDERING GUIDE 1 Model Temperature Range Package Description Package Option Branding AD8671AR –40°C to +125°C 8-Lead SOIC_N R-8 AD8671AR-REEL –40°C to +125°C 8-Lead SOIC_N R-8 AD8671AR-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8 AD8671ARZ –40°C to +125°C 8-Lead SOIC_N R-8 AD8671ARZ-REEL –40°C to +125°C 8-Lead SOIC_N R-8 AD8671ARZ-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8 AD8671ARMZ –40°C to +125°C 8-Lead MSOP RM-8 A0V AD8671ARMZ-REEL –40°C to +125°C 8-Lead MSOP RM-8 A0V AD8672AR –40°C to +125°C 8-Lead SOIC_N R-8 AD8672AR-REEL –40°C to +125°C 8-Lead SOIC_N R-8 AD8672AR-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8 AD8672ARZ –40°C to +125°C 8-Lead SOIC_N R-8 AD8672ARZ-REEL –40°C to +125°C 8-Lead SOIC_N R-8 AD8672ARZ-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8 AD8672ARMZ –40°C to +125°C 8-Lead MSOP RM-8 A0W AD8672ARMZ-REEL –40°C to +125°C 8-Lead MSOP RM-8 A0W AD8674AR –40°C to +85°C 14-Lead SOIC_N R-14 AD8674ARZ –40°C to +85°C 14-Lead SOIC_N R-14 AD8674ARZ-REEL –40°C to +85°C 14-Lead SOIC_N R-14 AD8674ARZ-REEL7 –40°C to +85°C 14-Lead SOIC_N R-14 AD8674ARU –40°C to +85°C 14-Lead TSSOP RU-14 AD8674ARUZ –40°C to +85°C 14-Lead TSSOP RU-14 AD8674ARUZ-REEL –40°C to +85°C 14-Lead TSSOP RU-14 1 Z = RoHS Compliant Part. Rev. E | Page 17 of 20 AD8671/AD8672/AD8674 NOTES Rev. E | Page 18 of 20 AD8671/AD8672/AD8674 NOTES Rev. E | Page 19 of 20 AD8671/AD8672/AD8674 NOTES ©2004–2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D03718–0–6/10(E) Rev. E | Page 20 of 20