Precision, Very Low Noise, Low Input Bias Current Operational Amplifiers AD8671/AD8672/AD8674 PIN CONFIGURATIONS 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. NC 1 V+ –IN 2 V+ TOP VIEW 6 OUT (Not to Scale) V– 4 5 NC NC = NO CONNECT Figure 1. 8-Lead SOIC_N (R-8) OUT A 1 AD8672 8 V+ 7 OUT B TOP VIEW 6 –IN B (Not to Scale) 5 +IN B V– 4 +IN A 3 Figure 2. 8-Lead MSOP (RM-8) OUT A 1 –IN A 2 Figure 3. 8-Lead SOIC-N (R-8) OUT A 1 +IN A 3 OUT B TOP VIEW 6 –IN B (Not to Scale) 5 +IN B V– 4 OUT A 1 –IN A 2 12 +IN D +IN A 3 –IN C 8 OUT C Figure 5. 14-Lead SOIC_N (R-14) 13 –IN D AD8674 12 +IN D TOP VIEW 11 V– +IN B 5 (Not to Scale) 10 +IN C TOP VIEW 11 V– +IN B 5 (Not to Scale) 10 +IN C 9 14 OUT D V+ 4 V+ 4 –IN B 6 V+ 7 +IN A 3 13 –IN D OUT B 7 8 AD8672 Figure 4. 8-Lead MSOP (RM-8) 14 OUT D AD8674 NC 7 +IN 3 03718-B-001 NC = NO CONNECT 8 AD8671 03718-B-002 TOP VIEW 6 OUT (Not to Scale) V– 4 5 NC –IN A 2 GENERAL DESCRIPTION NC 7 03718-B-003 PLL filters Filters for GPS Instrumentation Sensors and controls Professional quality audio 8 +IN 3 –IN A 2 APPLICATIONS AD8671 –IN B 6 9 –IN C OUT B 7 8 OUT C Figure 6. 14-Lead TSSOP (RU-14) 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 (–40°C to +125°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. 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. 03718-B-004 NC 1 –IN 2 03718-B-005 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 per amplifier Dual-supply operation: ±5 V to ±15 V Unity-gain stable No phase reversal 03718-B-006 FEATURES 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 © 2005 Analog Devices, Inc. All rights reserved. AD8671/AD8672/AD8674 TABLE OF CONTENTS Specifications..................................................................................... 3 Total Noise vs. Source Resistance............................................. 11 Electrical Characteristics, ±5.0 V ............................................... 3 Total Harmonic Distortion (THD) and Noise ....................... 12 Electrical Characteristics, ±15 V ................................................ 4 Driving Capacitive Loads.......................................................... 12 Absolute Maximum Ratings............................................................ 5 GPS Receiver............................................................................... 13 ESD CAUTION ............................................................................ 5 Band-Pass Filter.......................................................................... 13 Typical Performance Characteristics ............................................. 6 PLL Synthesizers and Loop Filters ........................................... 13 Applications..................................................................................... 11 Outline Dimensions ....................................................................... 14 Unity-Gain Follower Applications ........................................... 11 Ordering Guide .......................................................................... 16 Output Phase Reversal............................................................... 11 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 = 25°C, unless otherwise noted. Table 1. 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. C | Page 3 of 16 –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 ELECTRICAL CHARACTERISTICS, ±15 V VS = ±15 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 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 <TA < +125°C SR tS RL = 2 kΩ To 0.1% (10 V step, G = 1) To 0.01% (10 V step, G = 1) 4 2.2 6.3 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. C | Page 4 of 16 –13.2 –11 3.5 4.2 V V V V mA 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 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 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. Rating 36 V VS– to VS+ ±0.7 V Indefinite –65°C to +150°C –40°C to +125°C –65°C to +150°C 300°C Table 4. Package Characteristics Package Type 8-Lead MSOP (RM) 8-Lead SOIC_N (R) 14-Lead SOIC_N (R) 14-Lead TSSOP (RU) θJA 1 190 158 120 180 θJC 44 43 36 35 Unit °C/W °C/W °C/W °C/W Absolute maximum ratings apply at 25°C, unless otherwise noted. 1 θJA is specified for the worst-case conditions, that is., θJA 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 45 32 35 24 20 16 12 8 30 25 20 15 10 4 0 10 20 30 40 50 60 FREQUENCY (Hz) 70 80 90 100 0 –35 –30 –25 –20 –15 –10 –5 0 Figure 7. Voltage Noise Density vs. Frequency Figure 10. Input Offset Voltage Distribution 31.5 35 VS = ±15V TA = 25°C VS = ±15V 27.0 30 NUMBER OF AMPLIFIERS 22.5 18.0 13.5 9.0 25 20 15 10 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) 03718-B-008 5 0 –35 –30 –25 –20 –15 –10 –5 0 5 10 15 20 25 30 35 40 45 50 VOS (μV) 03718-B-011 VOLTAGE NOISE DENSITY (nV/√Hz) 5 10 15 20 25 30 35 40 45 VOS (μV) 03718-B-010 5 03718-B-007 0 VS = ±5V TA = 25°C 40 28 NUMBER OF AMPLIFIERS VOLTAGE NOISE DENSITY (nV/√Hz) VS = ±15V Figure 11. Input Offset Voltage Distribution Figure 8. Voltage Noise Density vs. Frequency 16 17.5 VS = ±15V 15 14 12.5 VOS (μV) 13 10.0 7.5 12 11 10 VS = ±5V 9 5.0 8 VS = ±15V 2.5 0 1 2 3 4 5 6 7 8 FREQUENCY (kHz) 9 10 6 –40 25 85 TEMPERATURE (°C) Figure 12. Input Offset Voltage vs. Temperature Figure 9. Voltage Noise Density vs. Frequency Rev. C | Page 6 of 16 125 03718-B-012 0 7 03718-B-009 VOLTAGE NOISE DENSITY (nV/√Hz) 15.0 AD8671/AD8672/AD8674 14.5 5.0 VS = ±5V 14.0 4.0 13.5 OUTPUT VOLTAGE (V) +IB 3.5 3.0 2.5 2.0 –IB 1.5 13.0 RL = 600Ω 12.5 12.0 11.5 11.0 1.0 10.5 0.5 25 85 125 TEMPERATURE (°C) 10.0 –40 03718-B-013 0 –40 25 85 03718-B-016 IB (nA) VS = ±15V RL = 2kΩ 4.5 125 TEMPERATURE (°C) Figure 13. Input Bias Current vs. Temperature Figure 16. Output Voltage High vs. Temperature 2.5 –11.0 VS = ±15V VS = ±15V 2.0 –11.5 –IB OUTPUT VOLTAGE (V) 1.0 0.5 +IB 0 –12.5 RL = 600Ω –13.0 –13.5 –14.0 85 125 TEMPERATURE (°C) –14.5 –40 25 85 125 TEMPERATURE (°C) Figure 14. Input Bias Current vs. Temperature Figure 17. Output Voltage Low vs. Temperature 60 4.0 270 VSY = ±15V RL = 10kΩ CL = 20pF ΦM = 59° 50 3.8 GAIN 40 OPEN-LOOP GAIN (dB) 3.6 3.4 3.2 3.0 VS = ±15V 225 180 135 30 90 20 PHASE 10 45 0 0 –10 –45 –20 –90 –30 –135 2.8 2.6 25 85 TEMPERATURE (°C) 125 03718-B-015 VS = ±5V 2.4 –40 –40 100k –180 1M FREQUENCY (Hz) 10M Figure 18. Open-Loop Gain and Phase Shift vs. Frequency Figure 15. Supply Current vs. Temperature Rev. C | Page 7 of 16 OPEN-LOOP PHASE (dB) 25 03718-B-014 –1.0 –40 ISY (mA) RL = 2kΩ 03718-B-017 –0.5 –12.0 03718-B-018 IB (nA) 1.5 AD8671/AD8672/AD8674 30000 VSY = ±15V VIN = 4V RL = 2kΩ ±5V VOLTAGE (1V/DIV) 25000 15000 ±15V 10000 25 85 125 TEMPERATURE (°C) 03718-B-022 0 –40 03718-B-019 5000 TIME (100μs/DIV) Figure 22. Large Signal Transient Response Figure 19. Open-Loop Gain vs. Temperature 50 40 VSY = ±15V VIN = 10mV RL = ∞ CL = 20pF AV = 100 20 VSY = ±15V VIN = 200mV p-p RL = 2kΩ AV = 10 VOLTAGE (50mV/DIV) CLOSED-LOOP GAIN (dB) 30 10 AV = 1 0 –10 –20 –30 1M 100k 10M 100M FREQUENCY (Hz) TIME (10μs/DIV) Figure 20. Closed-Loop Gain vs. Frequency Figure 23. Small Signal Transient Response 100 60 VS = ±15 SMALL SIGNAL OVERSHOOT (%) 90 80 70 60 50 AVO = 10 40 30 AVO = 100 AVO = 1 10 1k 10k 100k 1M 10M FREQUENCY (Hz) 50 –OS 40 30 20 10 +OS 100M 03718-B-021 20 0 100 03718-B-023 10k Figure 21. Output Impedance vs. Frequency 0 100 1k 10k CAPACITANCE (pF) Figure 24. Small Signal Overshoot vs. Load Capacitance Rev. C | Page 8 of 16 03718-B-024 –50 1k 03718-B-020 –40 IMPEDANCE (Ω) AVO (V/mV) 20000 AD8671/AD8672/AD8674 160 VSY = ±15V VOLTAGE (200mV/DIV) VS = ±15V VIN = 200mV p-p AV = –100 RL = 10kΩ 140 120 0V 100 PSRR (dB) VIN VOUT 80 60 –PSRR 40 +PSRR 20 0 0V TIME (4μs/DIV) –40 10 100 1k 10k 100k 1M 03718-B-028 03718-B-025 –20 10M FREQUENCY (Hz) Figure 25. Positive Overdrive Recovery Figure 28. PSRR vs. Frequency 135 VIN VOLTAGE (200mV/DIV) VS = ±2.5V TO ±18V VSY = ±15V VIN = 200mV p-p AV = –100 RL = 10kΩ 134 133 PSRR (dB) 0V 0V 132 131 130 VOUT 129 TIME (4μs/DIV) 127 –40 25 85 TEMPERATURE (°C) Figure 26. Negative Overdrive Recovery 125 03718-B-029 03718-B-026 128 Figure 29. PSRR vs. Temperature 160 VSY = ±15V VS = ±15V 140 VOLTAGE NOISE (50nV/DIV) 120 CMRR (dB) 100 80 60 40 20 100 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M 03718-B-027 –40 10 TIME (1μs/DIV) Figure 30. 0.1 Hz to 10 Hz Input Voltage Noise Figure 27. CMRR vs. Frequency Rev. C | Page 9 of 16 03718-B-030 0 –20 AD8671/AD8672/AD8674 0 VS = ±15V, ±5V –40 –60 –80 –100 –120 –140 100 1k 1M 10k 100k FREQUENCY (Hz) 10M 100M 03718-B-031 CHANNEL SEPARATION (dB) –20 Figure 31. Channel Separation Rev. C | Page 10 of 16 AD8671/AD8672/AD8674 APPLICATIONS UNITY-GAIN FOLLOWER APPLICATIONS VSY = ±15V 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 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. VOLTAGE (1V/DIV) VIN 03718-B-033 VOUT Figure 32 shows the uncompensated output response with a 10 kΩ resistor in the feedback and the compensated response with CF = 15 pF. Figure 33. Output Phase Reversal TOTAL NOISE VS. SOURCE RESISTANCE OUTPUT UNCOMPENSATED OUTPUT COMPENSATED 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. REF1 +OVER 23.23% VOLTAGE (1V/DIV) TIME (10μs/DIV) CH2 +OVER 7.885% TIME (100ns/DIV) 03718-B-032 Figure 34 shows the voltage noise, current noise, thermal noise, and total rms noise of the AD8671 as a function of the source 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. Figure 32. Transient Output Response 1000 C 100 in 10 en_t (4kR ST)1/2 en B A 1 10 100 1k 10k 100k SOURCE RESISTANCE (Ω) Figure 34. Noise vs. Source Resistance Rev. C | Page 11 of 16 1M 03718-B-034 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. TOTAL NOISE (nV/√Hz) OUTPUT PHASE REVERSAL 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 35 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 (10μs/DIV) Figure 36. AD8671 Capacitive Load Drive 0.0050 RF 0.0020 LT1007 0.0010 0.0005 500Ω 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 35. Total Harmonic Distortion and Noise 03718-B-037 PERCENTAGE 0.0100 Figure 37. 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 (10μs/DIV) Figure 38. Compensated Load Drive The output response of the circuit is shown in Figure 38. Rev. C | Page 12 of 16 CH2 +OVER 5.051% 03718-B-038 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. VSY = ±15V RL = 2kΩ CL = 1nF CF = 220pF VIN = 100mV AV = +2 AD8671/AD8672/AD8674 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 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 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 39 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 40 shows a second-order band-pass KRC filter. 100 1k 10k 100k R3 Figure 41. 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 40. 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 42. 2 4−K PHASE DETECTOR where: K =1+ R1 C1 10kΩ VCC 1nF CHARGE PUMP RB RA VCO D VEE IN Figure 42. PLL Filter Simplified Block Diagram Rev. C | Page 13 of 16 03718-B-042 2.25kΩ VIN 10M 1M Hz 2.25kΩ VCC R1 03718-B-041 BAND-PASS FILTER AD8671/AD8672/AD8674 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4.00 (0.1574) 3.80 (0.1497) 1 4 6.20 (0.2440) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.50 (0.0196) × 45° 0.25 (0.0099) 1.75 (0.0688) 1.35 (0.0532) 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 3.00 BSC 1 5 4.90 BSC 4 PIN 1 0.65 BSC 1.10 MAX 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.23 0.08 8° 0° 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 0.80 0.60 0.40 AD8671/AD8672/AD8674 8.75 (0.3445) 8.55 (0.3366) 4.00 (0.1575) 3.80 (0.1496) 14 8 1 7 6.20 (0.2441) 5.80 (0.2283) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 0.50 (0.0197) × 45° 0.25 (0.0098) 1.75 (0.0689) 1.35 (0.0531) 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 6.40 BSC 1 7 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 SEATING COPLANARITY PLANE 0.10 8° 0° 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 0.75 0.60 0.45 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 –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 +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 +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C 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 Z = Pb-free part. © 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 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