FEATURES Differential or Single-Ended Gain Block: ± (db) db Bandwidth: MHz Slew Rate: /µs Low Cost Output Current: ±ma Settling Time: ns to.% CMRR at MHz: db Differential Gain Error:.% Differential Phase Error:. Input Amplitude Limiting Single Operation Drives Cables Directly APPLICATIO S U Line Receivers Video Signal Processing Gain Limiting Oscillators Tape and Disc Drive Systems DESCRIPTIO LT9 Video Difference Amplifier U The LT 9 is a video difference amplifier optimized for operation on ± and a single supply. The amplifier has a fixed gain of db and features adjustable input limiting to control tough overdrive applications. It has uncommitted high input impedance () and () inputs, and can be used in differential or single-ended configurations. The LT9 s high slew rate /µs, wide bandwidth MHz, and ±ma output current make it ideal for driving cables directly. This versatile amplifier is easy to use for video or applications requiring speed, accuracy and low cost. The LT9 is available in -pin PDIP and SO packages., LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO U Wideband Differential Amplifier with Limiting Sine Wave Reduced by Limiting Ω pf TO pf INPUT NE9 µf µf k k LT9 OUTPUT V CONTROL V OUT V/DIV A V =, db BW = MHz LT9 TA LT9 TA khz SINE WAVE WITH V CONTROL =, V, V, V
LT9 ABSOLUTE AXI U RATI GS W W W (Note ) Total Supply Voltage (V to V )... V Differential Input Voltage... ±V Input Voltage... ±V S Output Short Circuit Duration (Note )... Continuous Operating Temperature Range LT9M (OBSOLETE)... C to C LT9C... C to C Maximum Junction Temperature... C Storage Temperature Range... C to C Lead Temperature (Soldering, sec)... C U BAL/V C IN IN V N PACKAGE -LEAD PDIP TOP VIEW S PACKAGE -LEAD PLASTIC SO T JMAX = C, θ JA = C/W (N) T JMAX = C, θ JA = C/W (S) J PACKAGE -LEAD CERDIP T JMAX = C, θ JA = C/W BAL/V C V OUT REF OBSOLETE PACKAGE ORDER PART NUMBER LT9CN LT9CS S PART MARKING 9 LT9MJ LT9CJ Consider the N or S Packages for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS, V REF = V, Null Pins and open circuit, T A = C, C L pf, unless otherwise noted. LT9M/C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V OS Input Offset Voltage All Packages mv I OS Input Offset Current. µa I B Input Bias Current ±. ±. µa e n Input Noise Voltage f O = khz nv/ Hz i n Input Noise Current f O = khz pa/ Hz R IN Input Resistance Either Input kω C IN Input Capacitance Either Input pf Input Voltage Range.. V CMRR Common Mode Rejection Ratio V CM =. to. db PSRR Power Supply Rejection Ratio V S = ±. to ±V db V OMAX Maximum Output Signal V S = ±V (Note ) ± ±. V V LIM Output Voltage Limit V i = ±., V C = V (Note ) ± ± mv V OUT Output Voltage Swing V S = ±V, V REF = V R L = k..9 V R L = Ω.. V V S = ±V, V REF = V R L = k.. V R L = Ω.. V, V REF = V, R L = k ± ± V G E Gain Error V O = ±V R L = k. % R L = Ω. % SR Slew Rate V O = ± V, R L = k (Notes, 9) V/µs FPBW Full-Power Bandwidth V O = V P-P (Note ).. MHz BW Small-Signal Bandwidth MHz t r, t f Rise Time, Fall Time R L = k, V O = ±mv, % to % (Note 9) ns t PD Propagation Delay R L = k, V O = ±mv, % to %. ns
LT9 ELECTRICAL CHARACTERISTICS, V REF = V, Null Pins and open circuit, T A = C, C L pf, unless otherwise noted. LT9M/C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Overshoot V O = ±mv % t s Settling Time V Step,.% (Note ) ns Diff A V Differential Gain R L = Ω (Note ). % Diff Ph Differential Phase R L = Ω (Note ). Deg P-P I S Supply Current ma V S =, V S = V, V REF =., Null Pins and open circuit, T A = C, C L pf, unless otherwise noted. LT9M/C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V OS Input Offset Voltage All Packages mv I OS Input Offset Current. µa I B Input Bias Current ±. ± µa Input Voltage Range. V CMRR Common Mode Rejection Ratio V CM = V to. db V LIM Output Voltage Limit V I = ±., V C = V (Note ) ± ± mv V OUT Output Voltage Swing R L = Ω to Ground V OUT High.. V V OUT Low.. V SR Slew Rate V O = V to V V/µs BW Small-Signal Bandwidth MHz I S Supply Current ma The denotes specifications which apply over the full operating temperature range of C T A C., V REF = V, Null Pins and open circuit, unless otherwise noted. LT9M SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V OS Input Offset Voltage N Package 9 mv V OS / T Input V OS Drift mv/ C I OS Input Offset Current. µa I B Input Bias Current ± ±. µa Input Voltage Range.. V CMRR Common Mode Rejection Ratio V CM =. to. db PSRR Power Supply Rejection Ratio V S = ±. to ± db V LIM Output Voltage Limit V I = ±., V C = V (Note ) ± ± mv V OUT Output Voltage Swing V S = ±V, R L = k. V V REF = V R L = Ω.9. V V S = ±V, R L = k.. V V REF = V R L = Ω. V G E Gain Error V O = ±V, R L = k % I S Supply Current ma
LT9 ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating temperature range of C T A C., V REF = V, Null Pins and open circuit, unless otherwise noted. LT9C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V OS Input Offset Voltage All Packages mv V OS / T Input V OS Drift µv/ C I OS Input Offset Current.. µa I B Input Bias Current ±. ± µa Input Voltage Range.. V CMRR Common Mode Rejection Ratio V CM =. to. db PSRR Power Supply Rejection Ratio V S = ±. to ± db V LIM Output Voltage Limit V I = ±., V C = V (Note ) ± ± mv V OUT Output Voltage Swing V S = ±V, R L = k..9 V V REF = V R L = Ω.. V V S = ±V, R L = k.. V V REF = V R L = Ω.. V G E Gain Error V O = ±V, R L = k % I S Supply Current ma Note : Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note : A heat sink is required to keep the junction temperature below absolute maximum when the output is shorted. Note : There are two limitations on signal swing. Output swing is limited by clipping or saturation in the output stage. Input swing is controlled by an adjustable input limiting function. On, the overload characteristic is output limiting, but on ±V the overload characteristic is input limiting. V OMAX is measured with the null pins open circuit. Note : Output amplitude is reduced by the input limiting function. The input limiting function occurs when the null pins, and, are tied together and raised to a potential.v or more above the negative supply. Note : Slew rate is measured between ±V on the output, with a ±.V input step. Note : Full-power bandwidth is calculated from the slew rate measurement: FPBW = SR/πV P. Note : Settling time measurement techniques are shown in Take the Guesswork Out of Settling Time Measurements, EDN, September 9, 9. Note : NTSC (.MHz). Note 9: AC parameters are % tested on the ceramic and plastic DIP packaged parts (J and N suffix) and are sample tested on every lot of the SO packaged part (S suffix). Optional Offset Nulling Circuit Input Limiting Connection Input Limiting with Offset Nulling LT9 LT9 LT9 V C V C LT9 TA INPUT OFFSET VOLTAGE CAN BE ADJUSTED OVER A ± mv RANGE WITH A kω TO kω POTENTIOMETER (NOTE ) (NOTE )
LT9 TYPICAL PERFOR A CE CHARACTERISTICS UW INPUT BIAS CURRENT (µa) Input Bias Current vs Common Mode Voltage C C C COMMON MODE VOLTAGE (V) LT9 TPC INPUT BIAS CURRENT (µa)...... Input Bias Current vs Temperature I OS I B I B TEMPERATURE ( C) LT9 TPC COMMON MODE VOLTAGE (V) Common Mode Voltage vs Supply Voltage V COMMON MODE V COMMON MODE C C C C C C ±V SUPPLY VOLTAGE (V) LT9 TPC EQUIVALENT INPUT NOISE VOLTAGE (nv/ Hz) Equivalent Input Noise Voltage vs Frequency T A = C R S = Ω k k k EQUIVALENT INPUT NOISE CURRENT (pa/ Hz) Equivalent Input Noise Current vs Frequency T A = C R S = k k k k SUPPLY CURRENT (ma) Supply Current vs Supply Voltage C C C ±SUPPLY VOLTAGE (V) LT9 TPC LT9 TPC LT9 TPC Gain, Phase vs Frequency. Gain Error vs Temperature db Bandwidth vs Supply Voltage VOLTAGE GAIN (db) T A = C R L = k k PHASE GAIN M M M PHASE SHIFT (DEGREES) GAIN ERROR (%).... R L = k R L = Ω TEMPERATURE ( C) db BANDWIDTH (MHz) T A = C, C, C SUPPLY VOLTAGE (V) LT9 TPC LT9 TPC LT9 TPC9
LT9 TYPICAL PERFOR A CE CHARACTERISTICS UW OUTPUT IMPEDANCE (Ω) Output Impedance vs Frequency T A = C. k k k M M M LT9 TPC COMMON MODE REJECTION RATIO (db) k Common Mode Rejection Ratio vs Frequency (Output Referred) T A = C R L = k M M M LT9 TPC POWER SUPPLY REJECTION RATIO (db) Power Supply Rejection Ratio vs Frequency (Output Referred) T A = C V RIPPLE = ±mv k k k M M M LT9 TPC OUTPUT SHORT-CIRCUIT CURRENT (ma) 9 Output Short-Circuit Current vs Temperature TEMPERATURE ( C) OUTPUT VOLTAGE LIMITING (V) Output Voltage Limiting vs Supply Voltage BAL/V C PINS, FLOATING T A = C T A = C T A = C OUTPUT SWING OUTPUT SWING T A = C T A = C T A = C ±SUPPLY VOLTAGE (V) OUTPUT VOLTAGE (V) Output Voltage vs Voltage On Control Pins LIMITING LIMITING V S = T A = C R L = k VOLTAGE ON CONTROL PINS (V) LT9 TPC LT9 TPC LT9 TPC VOLTAGE GAIN (db) Voltage Gain vs Frequency with Control Voltage V C = V C = V V C = V V C = V T A = C 9 R L = k k M M M G LT9 TPC OUTPUT VOLTAGE SWING (V) Output Voltage Swing vs Load Resistance T A = C T A = C T A = C T A = C T A = C T A = C LOAD RESISTANCE (Ω) LT9 TPC SLEW RATE (V/µs) 9 Slew Rate vs Temperature SLEW RATE SLEW RATE R L = k V O = ±V TEMPERATURE ( C) LT9 TPC
LT9 TYPICAL PERFOR A CE CHARACTERISTICS UW OUTPUT VOLTAGE STEP (V) Output Voltage Step vs Settling Time Small-Signal Transient Response Large-Signal Transient Response T A = C R L = k mv mv SETTLING TIME (ns) LT9 TPC RISE TIME =.ns, PROPAGATION DELAY = ns LT9 TPC R L = Ω, SR = V/µs, SR = /µs LT9 TPC9 APPLICATIO S I FOR ATIO U W U U The LT9 is a video difference amplifier with a fixed gain of (db). The amplifier has two uncommitted high input impedance () and () inputs that can be used either differentially or single-ended. The LT9 includes a limiting feature that allows the amplifier to reduce its output as a function of DC voltage on the BAL/V C pins. The limiting feature uses input differential-pair limiting to prevent overload in subsequent stages. This technique allows extremely fast limiting action. Power Supply Bypassing OUTPUT INPUT Input Limiting The LT9 is quite tolerant of power supply bypassing. In some applications a.µf ceramic disc capacitor placed / inch from the amplifier is all that is required. db INPUT OVERDRIVE, V C =.V LT9 TA
LT9 APPLICATIO S I FOR ATIO U W U U A scope photo of the amplifier output with no supply bypassing is used to demonstrate this bypassing tolerance, R L = k. In many applications, and those requiring good settling time, it is important to use multiple bypass capacitors. A.µF ceramic disc in parallel with a.µf tantalum is recommended. Two oscilloscope photos with different bypass conditions are used to illustrate the settling time characteristics of the amplifier. Note that although the output waveform looks acceptable at V/DIV, when amplified to mv/div the settling time to mv is ns. The time drops to ns with multiple bypass capacitors, and does not exhibit the characteristic power supply ringing. Settling Time Good Bypass LT9 TA SETTLING TIME TO mv, SUPPLY BYPASS CAPACITORS =.µf.µf TANTALUM No Supply Bypass IN DEMO BOARD, R L = k Settling Time Poor Bypass SETTLING TIME TO mv, SUPPLY BYPASS CAPACITORS =.µf LT9 TA LT9 TA Cable Terminations The LT9 video difference amplifier has been optimized as a low cost cable driver. The ±ma guaranteed output current enables the LT9 to easily deliver. P-P into Ω, while operating on ± supplies, or.v P-P on a single supply. When driving a cable it is important to terminate the cable to avoid unwanted reflections. This can be done in one of two ways: single termination or double termination. With single termination, the cable must be terminated at the receiving end (Ω to ground) to absorb unwanted energy. The best performance can be obtained by double termination (Ω in series with the output of the amplifier, and Ω to ground at the other end of the cable). This termination is preferred because reflected energy is absorbed at each end of the cable. When using the double termination technique it is important to note that the signal is attenuated by a factor of, or db. For a cable driver with a gain of (LT9 gain of ), the db bandwidth is over MHz with no peaking. A Voltage Controlled Current Source The LT9 can be used to make a fast, precise, voltage controlled current source. The LT9 high speed differential amplifier senses the current delivered to the load. The input signal V IN, applied to the () input of the LT9,
LT9 APPLICATIO S I FOR ATIO U W U U Double Terminated Cable Driver Voltage Controlled Current Source LT9 V C Ω CABLE Ω Voltage Gain vs Frequency T A = C ±V IN LT9 k C C LT9 R.Ω I O = ±ma R L Ω VOLTAGE GAIN (db) Output Current Response LT9 TA9 k M M M C C = pf LT9 TA C C = pf will appear at the () input if the feedback loop is properly closed. In steady state the input signal appears at the output of the LT9, and / of this signal is applied across the sense resistor. Thus the output current is simply: C C = pf ±ma CURRENT SOURCE WITH DIFFERENT COMPENSATION CAPACITORS LT9 TA I O = V IN R The compensation capacitor C C forces the LT9 to be the dominate pole for the loop, while the LT9 is fast enough to be transparent in the feedback path. The ratio of the load resistor to the sense resistor should be approximately : or greater for easy compensation. For the example shown the load resistor is Ω, the sense resistor is.ω, and various loop compensation capacitors cause the output to exhibit an underdamped, critically and overdamped response. CABLE V IN Differential Video Loop Thru Amplifier for Power-Down Applications k k.k.k % RESISTOR WORST-CASE CMRR = db TYPICALLY = db LT9 OUTPUT LT9 TA 9
LT9 APPLICATIO S I FOR ATIO Murphy Circuits U W U U There are several precautions the user should take when using the LT9 in order to realize its full capability. Although the LT9 can drive a pf capacitive load, isolating the capacitance with Ω can be helpful. Precautions primarily have to do with driving large capacitive loads. Other precautions include:. Use a ground plane (see Design Note, High Frequency Amplifier Evaluation Board).. Do not use high source impedances. The input capacitance of pf, and R S = k, for instance, will give an MHz db bandwidth.. PC board socket may reduce stability. Driving Capacitive Load Driving Capacitive Load LT9 IN DEMO BOARD, C L = pf LT9 TA LT9 IN DEMO BOARD, C L = pf WITH Ω ISOLATING RESISTOR LT9 TA COAX LT9 LT9 X SCOPE PROBE LT9 TA An Unterminated Cable is a Large Capacitive Load A X Scope Probe is a Large Capacitive Load
LT9 SI PLIFIED SCHE ATIC W W V V BIAS V BIAS C M V C FF V V OUT * V BAL BAL REF Ω.k * SUBSTRATE DIODE, DO NOT FORWARD BIAS LT9 TA PACKAGE DESCRIPTIO U J Package -Lead CERDIP (Narrow. Inch, Hermetic) (Reference LTC DWG # --) CORNER LEADS OPTION ( PLCS). BSC (. BSC).. (..).. (..) FULL LEAD OPTION.. (..).. (..) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS.. (..) HALF LEAD OPTION.. (..). (.) BSC. (.) MAX OBSOLETE PACKAGE.. MIN. (.) MIN. (.) RAD TYP. (.) MAX.. (..) J 9 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LT9 PACKAGE DESCRIPTIO U N Package -Lead PDIP (Narrow. Inch) (Reference LTC DWG # --).. (..).. (..). ±. (. ±.).* (.) MAX.9. (.9.)....9.. ( ). (.) TYP. (.) BSC *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED. INCH (.mm). ±.* (. ±.). (.) MIN. (.). ±. (. ±.) MIN N 9 S Package -Lead Plastic Small Outline (Narrow. Inch) (Reference LTC DWG # --).9.9* (..).. (..).. (..) TYP..9 (..).. (..).. (..)..9 (..) TYP * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED." (.mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED." (.mm) PER SIDE. (.) BSC.. (.9.9)..** (..9) SO 9 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT9 A V = Video Difference Amp MHz BW, /µs Slew Rate Linear Technology Corporation McCarthy Blvd., Milpitas, CA 9- () -9 FAX: () - www.linear.com 9fa LT/CP.K REV A PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 99