LM6311 LM6311 Low Noise High Speed Voltage Feedback Operational Amplifier Literature Number: SNOS790A LM6311 Low Noise High Speed Voltage Feedback Operational Amplifier General Description Features The LM6311 is a low noise voltage feedback operational amplifier with low distortion. This makes the LM6311 ideal for signal recovery, high quality video, audio and medical imaging. The conventional voltage fedback design makes it easy to use in standard active filter circuits. The low distortion makes the LM6311 a good choice for driving high resolution analog-to-digital converters. The 50 mA current drive and good capacitive load tolerance make the LM6311 useful for driving analog-to-digital converters which have switched-capacitor type inputs. The LM6311 provides low noise and high speed for a 5V single supply designs, making it useful for desktop systems and portable designs. Y Y Y Y Y Y Y Y Applications High end consumer audio Professional video Medical imaging Instrumentation Differential amplifiers and active filters Telecommunications signal recovery et Y Y Y Y Y Y bs ol Connection Diagrams 110 MHz b3 dB bandwidth 2.3 nV/root-Hertz voltage noise 3.5 pA/root-Hertz current noise 50 mA output current 200V/ms slew rate Low distortion b60 dB @ 5 MHz Pin for external compensation Dual g 5V or single a 5V or a 12V supplies Guaranteed specs at a 5V e Y LM6311 Input Referred Voltage Noise V a e a 5V 8-Pin DIP/SO-8 TL/H/12546 – 1 O Top View Package Ordering Information TL/H/12546 – 16 NSC Drawing Number Package Marking Transport Media 8-Pin DIP LM6311IN N08E LM6311IN Rails 8-Pin SO-8 LM6311IM M08A LM6311IM Rails 8-Pin SO-8 LM6311IMX M08A LM6311IM 2.5k Units Tape and Reel TinyPaKTM is a trademark of National Semiconductor Corporation. C1996 National Semiconductor Corporation TL/H/12546 RRD-B30M76/Printed in U. S. A. http://www.national.com LM6311 Low Noise High Speed Voltage Feedback Operational Amplifier November 1995 Absolute Maximum Ratings (Note 1) Operating Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage Junction Temperature Range LM6311I ESD Tolerance (Note 2) Differential Input Voltage Thermal resistance (iJA) N Package, 8-pin Molded DIP SO-8 Package, 8 Pin Surface Mount Voltage at Input/Output Pin Supply Voltage (V a – Vb) Current at Input Pin Current at Output Pin (Note 3) Current at Power Supply Pin Lead Temperature (soldering, 10 sec) Storage Temp. Range 2000V g 10V (V a ), (Vb) 12V g 5 mA g 80 mA 80 mA 260§ C g 2.25V to g 6V b 40§ C s TJ s a 85§ C 125§ C/W 165§ C/W b 65§ C to a 150§ C Junction Temperature (Note 4) 150§ C g 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ e 25§ C, V a e 5V, V b e b 5V, VCM e VO e 0V and RL e % . Boldface limits apply at the temperature extreme S. Input Offset Voltage TCVOS Input Offset Voltage Average Drift IB Input Bias Current TCIB Input Bias Current Average Drift Ioffset TCIoffset CMRR CMVR a PSRR 0.5 LM6311I Limit (Note 6) Units 2.5 4.0 mV max 5 8 mV/§ C 30 75 0.3 Input Offset Current 0.5 Input Offset Current Average Drift VCM e g 2.5V Common Mode Voltage Range CMRR e 60 db Positive Power Supply Rejection Ratio Negative Power Supply Rejection Ratio mA max mA/§ C 5 14 0.02 Common Mode Rejection Ratio O b PSRR Typ (Note 5) bs ol VOS Conditions e Parameter et Symbol mA max mA/§ C 90 60 54 db min g 3.5 g 3.2 V V a e 4.5V to 5V Vb e b5.0V 75 62 55 db min V a e 5.0V Vb e b4.5V to b5.0V 75 62 55 db min CIN-CM Common-Mode Input Capacitance 2.5 pF CIN-DIFF Differential-Mode Input Capacitance 2.5 pF AVOL http://www.national.com Voltage Gain VO e b2V to a 2V RL e 1 kX 2 70 62 55 db 5V DC Electrical Characteristics g Unless otherwise specified, all limits guaranteed for TJ e 25§ C, V a e 5V, V b e b 5V, VCM e VO e 0V and RL e % . Boldface limits apply at the temperature extremes. (Continued) Symbol VO Parameter Output Swing Conditions RL e 100X RL e 1 kX Typ (Note 5) LM6311I Limit (Note 6) Units 3.4 3.1 1.2 V min b 3.4 b 3.1 b 1.2 V max 3.5 b 2.5 V min b 3.5 b 2.5 V max 3.9 b 3.9 Output Resistance IS Supply Current Closed Loop X max 0.1 16 17 14 g 5V AC Electrical Characteristics mA max e ROUT Unless otherwise specified, all limits guaranteed for TJ e 25§ C, V a Symbol Parameter et e 5V, V b e b 5V, VCM e VO e 0V and RL e 100X. Boldface limits apply at the temperature extremes. Conditions Typ (Note 5) LM6311I Limit (Note 6) Units Slew Rate AV e a 2, 2V Output Pulse 200 V/ms b 3 dB BW b 3db Bandwidth AV e a 1 110 MHz b 3 db BW b 3 dB Bandwidth AV e a 2 40 MHz Dg Dp en Differential Gain (Note 7) AV e a 2, 150X Load 0.12 % Differential Phase (Note 7) AV e a 2, 150X Load 0.35 Deg Input-Referred Voltage Noise 1 MHz k f k 100 MHz Input-Referred Current Noise 1 MHz k f k 100 MHz 2.3 3.5 nV 0Hz nV 0Hz O in bs ol SR 3 http://www.national.com 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ e 25§ C, V a e 5V, V b e 0V, VCM e 2.5V, VO e 2.5V and RL e % . Boldface limits apply at the temperature extremes. Parameter Conditions VOS Input Offset Voltage TCVOS Input Offset Voltage Average Drift IB Input Bias Current TCIB Input Bias Current Average Drift Ioffset Input Offset Current TCIoffset Input Offset Current Average Drift CMRR Common Mode Rejection Ratio VCM e 1.75 to 3.25 a PSRR Positive Power Supply Rejection Ratio V a e 4.75V to 6V CIN-CM Common-Mode Input Capacitance CIN-DIFF Differential-Mode Input Capacitance VO Output Swing Units 0.3 3.0 5.0 mV max 6 mV/§ C 16 30 0.3 0.6 6 http://www.national.com mA max mA/§ C 65 50 db min 70 60 50 db min et 90 RL e 100X to 2.5V 2.5 pF 2.5 pF 4.2 3.6 3.4 V min 0.9 1.4 1.6 V max 4.3 3.8 3.6 V min 0.70 1.2 1.4 V max 67 55 50 db 11 13 14 mA max bs ol Voltage Gain mA max mA/§ C 0.02 VO e 2.0V to 3.0V RL e 1 kX to 2.5V Supply Current O IS LM6311I Limit (Note 6) 5 RL e 1 kX to 2.5V AVOL Typ (Note 5) e Symbol 4 5V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ e 25§ C, V a e 5V, V b e 0V, VCM e 2.5V, VO e 2.5V and RL e 100X to 2.5V. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) LM6311I Limit (Note 6) Units SR Slew Rate AV e a 2, 0.5V Output Pulse 100 V/ms b 3dB BW b 3dB Bandwidth AV e a 2 40 MHz Note 1: Absolute maximum Ratings indicate limits beyond which damage to the device my occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical characteristics. Note 2: Human body model, 1.5 kX in series with 100 pF. Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150§ C. Note 4: The maximum power dissipation is a function of TJ(max) iJA and TA. The maximum allowable power dissipation at any ambient temperature is PD e (TJ(max) –TA)/iJA. All numbers apply for packages soldered directly into a PC board. Note 5: Typical values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. O bs ol et e Note 7: Differential Gain and Phase performace are sensitive to layout. Follow layout suggestions in text for best results. 5 http://www.national.com Typical Performance Curves TA e 25§ C, V a e a 5V, Vb e b5V, RF e 100X, RL e 100X unless noted g 5V CURVES AV e a 1 Gain and Phase vs Frequency bs ol et AV e a 2 Gain and Phase vs Frequency e TL/H/12546 – 3 TL/H/12546 – 4 O AV e b1 Gain and Phase vs Frequency http://www.national.com TL/H/12546 – 5 6 Typical Performance Curves TA e 25§ C, V a e a 5V, Vb e b5V, RF e 100X, RL e 100X unless noted (Continued) g 5V CURVES (Continued) AV e a 2 Reference to Ground Pulse Response AV e a 2 Pulse Response TL/H/12546 – 7 e TL/H/12546 – 6 AV e b1 Large Signal Pulse Response bs ol et AV e b1 Small Signal Pulse Response TL/H/12546 – 9 O TL/H/12546 – 8 7 http://www.national.com Typical Performance Curves TA e 25§ C, V a e a 5V, Vb e 0V, RF e 100X, RL e 100X to 2.5V unless noted (Continued) 5V CURVES AV e a 1 Gain and Phase vs Frequency bs ol et AV e a 2 Gain and Phase vs Frequency e TL/H/12546 – 10 TL/H/12546 – 11 O AV e b1 Gain and Phase vs Frequency http://www.national.com TL/H/12546 – 12 8 Typical Performance Curves TA e 25§ C, V a e a 5V, Vb e 0V, RF e 100X, RL e 100X to 2.5V unless noted (Continued) 5V CURVES (Continued) AV e b1 Large Signal Pulse Response AV e a 2 Pulse Response TL/H/12546 – 14 e TL/H/12546 – 13 bs ol et AV e b1 Small Signal Pulse Response O TL/H/12546 – 15 9 http://www.national.com Typical Performance Curves (Continued) Bandwidth vs Supply Voltage, 27 pF External Capacitor (25§ C) TL/H/12546 – 17 FIGURE 1 Non Inverting Amplifier Center-referenced Input et e Inverting Amplifier Center-referenced Input TL/H/12546 – 19 bs ol FIGURE 2 Center-referenced Output Ground-referenced Output TL/H/12546–20 TL/H/12546 – 21 FIGURE 3 LM6311 Maximum Undistorted Output Swing. Loads Tied to Ground. V a e 5V. O Exceeding the Output Range, a 5V Supply No Load TL/H/12546–22 TL/H/12546 – 23 FIGURE 4 http://www.national.com FIGURE 5 10 Application Information pins as possible. It is generally advisable to use two capacitors at each supply voltage pin. A small surface mount capacitor with a value of around 0.01 mF (10 nF), usually a ceramic type with good RF performance, should be placed closest to the pin. A larger capacitor, usually in the range of 1.0 mF to 4.7 mF, should also be placed near the pin. The larger capacitor should be a device with good RF characteristics and low ESR (equivalent series resistance) for best results. Ceramic and tantalum capacitors generally work well as the larger capacitor. It is very important to reduce capacitance at the input and output pins. The ground plane and any other planes (power, etc.) should be ‘‘opened up’’ or removed near the pins. The opening should extend to the middle of the nearest pins as a minimum. The LM6311 is built on a high performance bipolar process. The transistors used in this process have bandwidths much higher than the LM6311 itself. These transistors have a potential to oscillate or ring at 400 MHz to 1 GHz when used in layouts where the components are more than (/4 inch 6 mm) away from the op amp pins. These oscillations may produce apparent shifts in voltage offset or excess current consumption. To avoid this, keep the input and output resistors as close as possible to their respective pins. Spacing within (/8× (3 mm) or less is recommended for best results. For best performance, low inductance resistors, such as chip resistors, are recommended. The use of wirewound resistors is strongly not recommended. DIP devices should use socket pins which are flush with the board. Conventional sockets have additional capacitance and are not recommended. Obviously, the use of wirewrapped sockets or the ‘‘white plastic’’ push in prototype boards is strongly not recommended. GENERAL INFORMATION The LM6311 is a high speed complementary bipolar amplifier with good video performance. The LM6311 can operate on g 2.5V supplies, or from a a 5V single supply. The LM6311 is available in two package types: DIPs for through hole designs, and SO-8 surface mount packages. Benefits of the LM6311 LOW NOISE The low noise performance of the LM6311 (typically 2.3 nV per root-hertz) makes the LM6311 a good choice for signal recovery, high gain amplifiers other low noise designs. e BALANCED DIFFERENTIAL INPUTS The relatively low offset currents and low offset voltage of the LM6311 make it easy to design differential signal recovery circuits. The low offset currents and voltage feedback design make it easy to use the LM6311 in conventional active filter designs. Using the LM6311 LIMITS AND PRECAUTIONS et a 5V SINGLE SUPPLY OPERATION Single supply operation can avoid the cost of split power supplies, and make it easier to use the LM6311 in single supply digital systems. The LM6311 provides high bandwidth for a 5V single supply operation. See Figure 1 . bs ol Supply Voltage The absolute maximum supply voltage which may be applied to the LM6311 is 12V. Designers should not design for more than 10V nominal, and carefully check supply tolerances under all conditions so that the voltages do not exceed the maximum. Notes for a 5V Single Supply Operation Differential Input Voltage Differential input voltage is the difference in voltage between the non-inverting ( a ) input and the inverting input (b) of the op amp. The absolute maximum differential input voltage is g 10V across the inputs. This limit also applies when there is no power supplied to the op amp. Very fast input pulses into high gain circuits may cause the output to saturate, leading to an overload recovery time in the millisecond range. This requires inputs which are faster than those usually used in video systems and gain levels which will push the output of the amplifier toward the limit of its output swing. The LM6311 provides good high speed performance at a 5V, however, certain limitations should be observed in applying the LM6311. O INPUT VOLTAGE RANGE Input voltage should be near the center of the V a and Vb supplies. For 5V and ground, the inputs should be between 1.75V and 3.25V. Inputs beyond this range will limit the output swing, reduce the common mode rejection and power supply rejection, lower the bandwidth, and tend to greatly increase distortion. For a 5V designs, using a reference voltage near a 2.5V is recommended. See Figure 2 . Layout and Power Supply Bypassing Since the LM6311 is a high speed (over 50 MHz) device, good high speed circuit layout practices should be followed. This should include the use of ground planes, adequate power supply bypassing, removing metal from around the input pins to reduce capacitance, and careful routing of the output signal lines to keep them away from the input pins. The power supply pins should be bypassed on both the negative and positive supply inputs with capacitors placed close to the pins. Surface mount capacitors should be used for best performance, and should be placed as close to the OUTPUT VOLTAGE SWING Output voltage swing will depend on the load and on what voltage (ground or 2.5V) is on the other side of the load. At room temperature (25§ C) and a 5V supply with a 1 kX load tied to 2.5V, the LM6311 will swing from 1.0V to 4.0V. For a ground referenced load, this output range will shift about 400 mV – 500 mV towards ground. See Figure 3 for schematics of loads referenced to the center and to ground. 11 http://www.national.com Application Information (Continued) to terminate cables and long circuit traces with their characteristic impedance to reduce reflected signals. Reflections should not be confused with overshoot. Reflections will depend on cable length, while overshoot will depend on load and feedback resistance and capacitance. When determining the type of problem, often removing or drastically shortening the cable will reduce or eliminate reflections. Overshoot can exist without a cable attached to the op amp output. If the load is too heavy (too low a resistance) for the output swing, or the output tries to go too close to either V a or Vb power supply rail, the output will ‘‘foldback’’ as shown in Figure 4 . This will distort the output signal. This should be avoided. There are many ways to avoid this, such as limiting the input signal, lowering the gain of the amplifier, or using a lighter (higher resistance) load. For designs which require low distortion, it is recommended to keep the output of the amplifier more than 300 mV away from the levels where visible distortion can be seen on an oscilloscope. For designs with wide temperature ranges which have low distortion requirements, additional margin may be required, which should be determined expermentally. See Figure 5 . Figure 5 was recorded when visible distortion was just visible. Other High Speed and Video Amplifiers National Semiconductor has an extensive line of high speed amplifiers, with a range of operating voltage from 3V single supply to g 15V, and a range of package types, such as the space saving SOT23-5 TinyPaKTM (3.05 mm x 3.00 mm x 1.43 mmÐabout the size of a grain of rice) and a wide S0-8 for better power dissipation. This op amp line includesÐ LM6171 100 MHz Low Distortion Amplifier with l 3000 V/ms slew rate. Voltage Feedback design draws only 2.5 mA. Specified at g 15V and g 5V supplies. LM7131 TinyPaK (SOT23-5) Video amplifier with 70 MHz gain bandwidth. Specified at 3V, 5V and g 5V supplies. LM7171 200 MHz Voltage Feedback amplifier with 100 mA output current and 4000V/ms slew rate. Supply current of 6.5 mA. Specified at g 15V and g 5V. Information on these parts is available from your National Semiconductor representative. bs ol et e External Compensation Capacitor An external compensation capacitor of 27 pF is recommended for use with the LM6311. The capacitor should be connected between pin 5 and ground, and should be placed close to the LM6311. This capacitor increases the phase margin of the LM6311, allowing it to be used in low gain circuits, such as AV e a 1. A lower value of compensation capacitor (such as 10 pF) will increase bandwidth at the expense of phase margin. This will result in more peaking and ringing with low gain circuits (AV less than 5). A lower value of compensation capacitor can be useful for single supply ( a 5V only) circuits. Designer should avoid very low values of compensation capacitors in low gain circuits since this will reduce phase margin and may cause some circuits to oscillate. SPICE Macromodel A SPICE macromodel of the LM6311 and many other National Semiconductor op amps is available at no charge from your National Semiconductor representative. O Reflections The output slew rate of the LM6311 is fast enough to produce reflected signals in many cables and long circuit traces. For best pulse performance, it may be necessary http://www.national.com 12 e Physical Dimensions inches (millimeters) unless otherwise noted O bs ol et 8-Pin Small Outline Package Order Number LM6311IM or LM6311MX NS Package Number M08A 13 http://www.national.com e Lit. Ý108288-001 et LM6311 Low Noise High Speed Voltage Feedback Operational Amplifier Physical Dimensions inches (millimeters) unless otherwise noted (Continued) bs ol 8-Pin Molded DIP Package Order Number LM6311IN NS Package Number N08E LIFE SUPPORT POLICY O NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation 1111 West Bardin Road Arlington, TX 76017 Tel: 1(800) 272-9959 Fax: 1(800) 737-7018 http://www.national.com 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Europe Fax: a49 (0) 180-530 85 86 Email: europe.support @ nsc.com Deutsch Tel: a49 (0) 180-530 85 85 English Tel: a49 (0) 180-532 78 32 Fran3ais Tel: a49 (0) 180-532 93 58 Italiano Tel: a49 (0) 180-534 16 80 National Semiconductor Hong Kong Ltd. 13th Floor, Straight Block, Ocean Centre, 5 Canton Rd. Tsimshatsui, Kowloon Hong Kong Tel: (852) 2737-1600 Fax: (852) 2736-9960 National Semiconductor Japan Ltd. Tel: 81-043-299-2308 Fax: 81-043-299-2408 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. 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