FEATURES DESCRIPTIO APPLICATIO S. LT1259/LT1260 Low Cost Dual and Triple 130MHz Current Feedback Amplifiers with Shutdown TYPICAL APPLICATIO

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1 LT/LT Low Cost Dual and Triple MHz Current Feedback Amplifiers with Shutdown FEATRES MHz andwidth on ±V.d Gain Flatness >MHz Completely Off in Shutdown, µa Supply Current High Slew Rate: V/µs Wide Supply Range: ±V(V) to ±V(V) ma Output Current Low Supply Current: ma/amplifier Differential Gain:.% Differential Phase:. Fast Turn-On Time: ns Fast Turn-Off Time: ns -Pin and -Pin Narrow SO Packages APPLICATIO S RG Cable Drivers Spread Spectrum Amplifiers MX Amplifiers Composite Video Cable Drivers Portable Equipment DESCRIPTIO The LT contains two independent MHz current feedback amplifiers, each with a shutdown pin. These amplifiers are designed for excellent linearity while driving cables and other low impedance loads. The LT is a triple version especially suited to RG video applications. These amplifiers operate on all supplies from single V to ±V and draw only ma per amplifier when active. When shut down, the LT/LT amplifiers draw zero supply current and their outputs become high impedance. Only two LTs are required to make a complete -input RG MX and cable driver. These amplifiers turn on in only ns and turn off in ns, making them ideal in spread spectrum and portable equipment applications. The LT/LT amplifiers are manufactured on Linear Technology s proprietary complementary bipolar process., LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO -Input Video MX Cable Driver Square Wave Response V IN A R G.k / LT CHANNEL A SELECT EN A R F.k CALE V OT CALE OTPT V IN R G.k / LT EN R F.k LT/ TA R L = Ω f = MHz LT/ TA

2 LT/LT ASOLTE AXI RATI GS W W W Supply Voltage... ±V Input Current... ±ma Output Short-Circuit Duration (Note )...Continuous Specified Temperature Range (Note )... C to C Operating Temperature Range... C to C Storage Temperature Range... C to C Junction Temperature (Note )... C Lead Temperature (Soldering, sec)... C W PACKAGE/ORDER I FOR ATIO IN A IN A IN IN N PACKAGE -LEAD PLASTIC DIP TOP VIEW A EN A OT A V V OT EN S PACKAGE -LEAD PLASTIC SOIC T JMAX = C, θ JA = C/W (N) T JMAX = C, θ JA = C/W (S) ORDER PART NMER LTCN LTCS LTIN LTIS IN R IN R IN G IN G IN IN TOP VIEW R G EN R OT R V EN G OT G V OT EN N PACKAGE S PACKAGE -LEAD PLASTIC DIP -LEAD PLASTIC SOIC T JMAX = C, θ JA = C/W (N) T JMAX = C, θ JA = C/W (S) ORDER PART NMER LTCN LTCS LTIN LTIS Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS C T A C, each amplifier V CM = V, ±V V S ±V, EN pins = V, pulse tested, unless otherwise noted. SYMOL PARAMETER CONDITIONS MIN TYP MAX NITS V OS Input Offset Voltage T A = C mv mv I IN Input Offset Voltage Drift µv/ C Noninverting Input Current T A = C. µa µa I IN Inverting Input Current T A = C µa µa e n Input Noise Voltage Density f = khz, R F = k, R G = Ω, R S = Ω. nv/ Hz i n Noninverting Input Noise Current Density f = khz. pa/ Hz i n Inverting Input Noise Current Density f = khz pa/ Hz R IN Input Resistance V IN = ±V, V S = ±V MΩ V IN = ±V, V S = ±V MΩ C IN Input Capacitance Enabled pf Disabled pf C OT Output Capacitance Disabled. pf V IN Input Voltage Range V S = ±V, T A = C ± ±. V ± V V S = ±V, T A = C ± ±. V ± V

3 ELECTRICAL CHARACTERISTICS C T A C, each amplifier V CM = V, ±V V S ±V, EN pins = V, pulse tested, unless otherwise noted. LT/LT SYMOL PARAMETER CONDITIONS MIN TYP MAX NITS V OT Maximum Output Voltage Swing V S = ±V, R L = k ±. ±. V V S = ±V, R L = Ω, T A = C ±. ±. V ±. V CMRR Common-Mode Rejection Ratio V S = ±V, V CM = ±V, T A = C d V S = ±V, V CM = ±V d V S = ±V, V CM = ±V, T A = C d V S = ±V, V CM = ±V d Inverting Input Current V S = ±V, V CM = ±V, T A = C. µa/v Common-Mode Rejection V S = ±V, V CM = ±V µa/v V S = ±V, V CM = ±V, T A = C. µa/v V S = ±V, V CM = ±V µa/v PSRR Power Supply Rejection Ratio V S = ±V to ±V, EN Pins at V, T A = C d V S = ±V to ±V, EN Pins at V d Noninverting Input Current V S = ±V to ±V, EN Pins at V, T A = C na/v Power Supply Rejection V S = ±V to ±V, EN Pins at V na/v Inverting Input Current V S = ±V to ±V, EN Pins at V, T A = C. µa/v Power Supply Rejection V S = ±V to ±V, EN Pins at V µa/v A V Large-Signal Voltage Gain V S = ±V, V OT = ±V, R L = k d V S = ±V, V OT = ±V, R L = Ω d R OL Transresistance, V OT / I IN V S = ±V, V OT = ±V, R L = k kω V S = ±V, V OT = ±V, R L = Ω kω I OT Maximum Output Current R L = Ω, T A = C ma I S Supply Current per Amplifier V S = ±V, V OT = V, T A = C.. ma (Note ). ma V S = ±V, V OT = V, T A = C.. ma Disable Supply Current per Amplifier V S = ±V, EN Pin Voltage =.V, R L = Ω. µa V S = ±V, Sink µa From EN Pin. µa Enable Pin Current V S = ±V, EN Pin Voltage = V, T A = C µa µa SR Slew Rate (Note ) T A = C V/µs t ON Turn-On Delay Time (Note ) A V =, T A = C ns t OFF Turn-Off Delay Time (Note ) A V =, T A = C ns t r, t f Small-Signal Rise and Fall Time V S = ±V, R F = R G =.k, R L = Ω. ns Propagation Delay V S = ±V, R F = R G =.k, R L = Ω. ns Small-Signal Overshoot V S = ±V, R F = R G =.k, R L = Ω % t S Settling Time.%, V OT = V, R F = R G =.k, R L = k ns Differential Gain (Note ) V S = ±V, R F = R G =.k, R L = Ω. % Differential Phase (Note ) V S = ±V, R F = R G =.k, R L = Ω. DEG C T A C, each amplifier V CM = V, ±V V S ±V, EN pins = V, pulse tested, unless otherwise noted. SYMOL PARAMETER CONDITIONS MIN TYP MAX NITS V OS Input Offset Voltage mv I IN Noninverting Input Current µa I IN Inverting Input Current µa R IN Input Resistance V IN = ±V, V S = ±V MΩ A V Large-Signal Gain d I S Disable Supply Current per Amplifier V S = ±V, EN Pin Voltage =.V, R L = Ω µa Enable Pin Current V S = ±V, EN Pin Voltage = V µa

4 LT/LT ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the specified operating temperature range. Note : A heat sink may be required depending on the power supply voltage and how many amplifiers have their outputs short circuited. Note : Commercial grade parts are designed to operate over the temperature range of C to C but are neither tested nor guaranteed beyond C to C. Industrial grade parts specified and tested over C to C are available on special request. Consult factory. Note : Ground pins are not internally connected. For best performance, connect to ground. Note : T J is calculated from the ambient temperature T A and the power dissipation P D according to the following formulas: LTCN/LTIN: T J = T A (P D C/W) LTCS/LTIS: T J = T A (P D C/W) LTCNLTIN/: T J = T A (P D C/W) LTCS/LTIS: T J = T A (P D C/W) Note : The supply current of the LT/LT has a negative temperature coefficient. See Typical Performance Characteristics. Note : Slew rate is measured at ±V on a ±V output signal while operating on ±V supplies with R F = k, R G = Ω and R L = k. Note : Turn-on delay time is measured while operating on ±V supplies with R F = k, R G = Ω and R L = Ω. The t ON is measured from control input to appearance of.v at the output, for V IN =.V. Likewise, turn-off delay time is measured from control input to appearance of.v on the output for V IN =.V. Note : Differential gain and phase are measured using a Tektronix TSGYC/NTSC signal generator and a Tektronix R Video Measurement Set. The resolution of this equipment is.% and.. Six identical amplifier stages were cascaded giving an effective resolution of.% and.. TYPICAL AC PERFOR A CE W SMALL SIGNAL SMALL SIGNAL SMALL SIGNAL V S (V) A V R L (Ω) R F (Ω) R G (Ω) d W (MHz).d W (MHz) PEAKING (d) ±.k.k. ±.k.k ±.k. ±. TYPICAL PERFOR A CE CHARACTERISTICS W GAIN (d) ±V Frequency Response, A V = GAIN V S = ±V R L = Ω R F = R G =.k PHASE FREQENCY (MHz) LT/ TPC PHASE (DEG) GAIN (d) ±V Frequency Response, A V = GAIN PHASE V S = ±V R L = Ω R F =.k R G = Ω FREQENCY (MHz) LT/ TPC PHASE (DEG)

5 LT/LT TYPICAL PERFOR A CE CHARACTERISTICS W GAIN (d) ±V Frequency Response, A V = GAIN V S = ±V R L = Ω R F = R G =.k PHASE FREQENCY (MHz) LT/ TPC PHASE (DEG) GAIN (d) ±V Frequency Response, A V = GAIN V S = ±V R L = Ω R F = Ω R G =.Ω PHASE FREQENCY (MHz) LT/ TPC PHASE (DEG) TOTAL HARMONIC DISTORTION (%).. Total Harmonic Distortion vs Frequency V S = ±V R L = Ω R F = R G =.k V O = V RMS V O = V RMS DISTORTION (dc) nd and rd Harmonic Distortion vs Frequency V S = ±V V O = V P-P A V = d R L = Ω R F =.k ND RD OTPT VOLTAGE (VP-P) Maximum ndistorted Output vs Frequency A V = A V = V S = ±V R L = k R F = k A V =. k k FREQENCY (Hz) k FREQENCY (MHz) FREQENCY (MHz) LT/ TPC LT/ TPC LT/ TPC POWER SPPLY REJECTION (d) Power Supply Rejection vs Frequency POSITIVE V S = ±V R L = OOΩ R F = R G = k NEGATIVE SPOT NOISE (nv/ Hz OR pa/ Hz) Spot Noise Voltage and Current vs Frequency i n e n i n OTPT IMPEDANCE (Ω) Output Impedance vs Frequency V S = ±V R F = R G = k k k M M FREQENCY (Hz) M k k FREQENCY (Hz) k. k k M M FREQENCY (Hz) M LTC/ TPC LT/ TPC LT/ TPC

6 LT/LT TYPICAL PERFOR A CE CHARACTERISTICS W OTPT IMPEDANCE (kω). k Output Impedance in Shutdown vs Frequency V S = ± A V = R F =.k M M M FREQENCY (Hz) LOAD CAPACITANCE (pf) Maximum Capacitive Load vs Feedback Resistor V S = ±V V S = ±V A V = R L = Ω PEAKING d FEEDACK RESISTOR (kω) SPPLY CRRENT (ma) Supply Current vs Supply Voltage C C C SPPLY VOLTAGE (±V) LT/ TPC LT/ TPC LT/ TPC OTPT SATRATION VOLTAGE (V) V.... Output Saturation Voltage vs Temperature V R L = ±V V S ±V TEMPERATRE ( C) COMMON-MODE RANGE (V) V V Input Common-Mode Limit vs Temperature V = V TO V V = V TO V TEMPERATRE ( C) OTPT SHORT-CIRCIT CRRENT (ma) Output Short-Circuit Current vs Junction Temperature TEMPERATRE ( C) LT/ TPC LT/ TPC LT/ TPC OTPT STEP (V) Settling Time to mv vs Output Step NONINVERTING INVERTING V S = ±V R F =.k SETTLING TIME (ns) LT/ TPC Small-Signal Rise Time V S = ±V A V = R F = R G =.k R L = Ω LT/ G

7 SI PLIFIED SCHE ATIC W W, each amplifier LT/LT V IN IN OT EN V LT/ SS APPLICATIO S I FOR ATIO W Feedback Resistor Selection The small-signal bandwidth of the LT/ LT are set by the external feedback resistors and the internal junction capacitors. As a result, the bandwidth is a function of the supply voltage, the value of the feedback resistor, the closed-loop gain and the load resistor. The LT/LT have been optimized for ±V supply operation and have a d bandwidth of MHz. See resistor selection guide in Typical AC Performance table. Capacitance on the Inverting Input Current feedback amplifiers require resistive feedback from the output to the inverting input for stable operation. Take care to minimize the stray capacitance between the output and the inverting input. Capacitance on the inverting input to ground will cause peaking in the frequency response (and overshoot in the transient response). See the section on Demo oard Information. Capacitive Loads The LT/LT can drive capacitive loads directly when the proper value of feedback resistor is used. The graph of Maximum Capacitive Load vs Feedback Resistor should be used to select the appropriate value. The value shown is for d peaking when driving a Ω load at a gain of. This is a worst case condition. The amplifier is more stable at higher gains. Alternatively, a small resistor (Ω to Ω) can be put in series with the output to isolate the capacitive load from the amplifier output. This has the advantage that the amplifier bandwidth is only reduced when the capacitive load is present. The disadvantage is that the gain is a function of the load resistance. Power Supplies The LT/LT will operate from single or split supplies from ±V (V total) to ±V (V total). It is not necessary to use equal value split supplies, however the offset voltage and inverting input bias current will change. The offset voltage changes about µv per volt of supply mismatch. The inverting bias current can change as much as µa per volt of supply mismatch though typically, the change is about.µa per volt. Slew Rate The slew rate of a current feedback amplifier is not independent of the amplifier gain configuration the way slew rate is in a traditional op amp. This is because both the input stage and the output stage have slew rate limitations. In the inverting mode, and for higher gains in the noninverting mode, the signal amplitude between the input pins is small and the overall slew rate is that of the output stage. For gains less than ten in the noninverting mode, the overall slew rate is limited by the input stage.

8 LT/LT APPLICATIO S I FOR ATIO W The input slew rate of the LT/LT is approximately V/µs and is set by internal currents and capacitances. The output slew rate is set by the value of the feedback resistors and internal capacitances. At a gain of with at k feedback resistor and ±V supplies, the output slew rate is typically V/µs. Larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced. The graph of Maximum ndistorted Output vs Frequency relates the slew rate limitations to sinusoidal input for various gains. Large-Signal Transient Response, A V = looks like a.pf capacitor in parallel with a k resistor, excluding feedback resistor effects. These amplifiers are designed to operate with open drain logic: the EN pins have internal pullups and the amplifiers draw zero current when these pins are high. To activate an amplifier, its EN pin is pulled to ground (or at least V below the positive supply). The enable pin current is approximately µa when activated. Input referred switching transients with no input signal applied are only mv positive and mv negative with R L = Ω. Output Switching Transient EN OTPT V S = ±V V IN = V R F = R G =.k R L = Ω LT/LT AI V S = ±V R F = R G =.k R L = Ω LT/LT AI Large-Signal Transient Response, A V = The enable/disable times are very fast when driven from standard V logic. The amplifier enables in about ns (% point to % point) while operating on ±V supplies. Likewise the disable time is approximately ns (% point to % point) or ns to % of the final value. The output decay time is set by the output capacitance and load resistor. Amplifier Enable Time, A V = OTPT V S = ±V R F = k R G = Ω R L = Ω LT/LT AI EN Enable/Disable The LT/LT amplifiers have a unique high impedance, zero supply current mode which is controlled by independent EN pins. When disabled, an amplifier output V S = ±V V IN =.V R F = k R G = Ω R L = Ω LT/LT AI

9 LT/LT APPLICATIO S I FOR ATIO W Amplifier Disable Time, A V = Amplifier Enable/Disable Time, A V = EN EN OTPT OTPT V S = ±V V IN =.V R F = k R G = Ω R L = Ω LT/LT AI V S = ±V V IN = VPP at MHz R F = R G =.k R L = Ω LT/LT AI Differential Input Signal Swing The differential input swing is limited to about ±V by an ESD protection device connected between the inputs. In normal operation, the differential voltage between the input pins is small, so this clamp has no effect. In the disabled mode however, the differential swing can be the same as the input swing, and the clamp voltage will set the maximum allowable input voltage. TYPICAL APPLICATIO S -Input Video MX Cable Driver The application on the first page shows a low cost, - input video MX cable driver. The scope photo displays the cable output of a MHz square wave driving Ω. In this circuit the active amplifier is loaded by R F and R G of the disabled amplifier, but in this case it only causes a.% gain error. The gain error can be eliminated by -Input Video MX Switching Response V S = ±V V IN A = V IN = VPP at MHz R F = R G =.k R L = Ω LT/LT TA EN A EN configuring each amplifier as a unity-gain follower. The switching time between channels is ns when both EN A and EN are driven. -Input RG MX Cable Driver Demonstration oard A complete -input RG MX has been fabricated on PC Demo oard #A. The board incorporates two LTs with outputs summed through back termination resistors as shown in the schematic. There are several things to note about Demo oard #A:. The feedback resistors of the disabled LT load the enabled amplifier and cause a small (% to %) gain error depending on the values of R F and R G. Configure the amplifiers as unity-gain followers to eliminate this error.. The feedback node has minimum trace length connecting R F and R G to minimize stray capacitance.. Ground plane is pulled away from R F and R G on both sides of the board to minimize stray capacitance.

10 LT/LT TYPICAL APPLICATIO S. Capacitors C and C are optional and only needed to reduce overshoot when EN or EN are activated with a long inductive ground wire.. The R, G and amplifiers have slightly different frequency responses due to different output trace routing to R F (between pins and ). All amplifiers have slightly less bandwidth in PC # than when measured alone as shown in the Typical AC Performance table.. Part-to-part variation can change the peaking by ±.d. RG Demo oard Gain vs Frequency V S = ±V R L = Ω R F = R G =.k ALL HOSTILE CROSSTALK (d) RG Demo oard All Hostile Crosstalk V S = ±V R L = Ω R F = R G =.k R S = Ω G R FREQENCY (MHz) P-DIP PC oard # LT/ TA GAIN (d) G R FREQENCY (MHz) LT/ TA R G EN R R R R R R EN C V R R V C C R R C G GAIN (d) RG Demo oard Gain vs Frequency V S = ±V R L = Ω R F = R G =.k G R, R G R R R R R R C C R C R C R () - LT RG AMPLIFIER DEMONSTRATION OARD FREQENCY (MHz) LT/ TA LT/ TA

11 LT/LT PACKAGE DESCRIPTIO.. (..). ±. (. ±.) Dimensions in inches (millimeters) unless otherwise noted. N Package -Lead PDIP (Narrow.) (LTC DWG # --).. (..).* (.) MAX.. (..) ( ). (.) MIN. (.) MIN. (.) MIN. ±. (. ±.) *THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED. INCH (.mm).. (..). ±. (. ±.) N Package -Lead PDIP (Narrow.) (LTC DWG # --).. (..). ±.*. (. ±.) (.) TYP. ±. (. ±.).* (.) MAX N.. (..).. (..) ( ).. (..). (.) MIN TYP. (.) MIN.. (..). (.) MIN. ±. (. ±.) *THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED. INCH (.mm).. (..).. (..).... TYP.. (..).. (..) * DIMENSION DOES NOT INCLDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED." (.mm) PER SIDE ** DIMENSION DOES NOT INCLDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED." (.mm) PER SIDE. (.) TYP. ±. (. ±.) S Package -Lead Plastic Small Outline (Narrow.) (LTC DWG # --). (.) TYP.. (..) S Package -Lead Plastic Small Outline (Narrow.) (LTC DWG # --).. (..). ±.* (. ±.).. (..)..* (..)..* (..) N..** (..) S (..) * DIMENSION DOES NOT INCLDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED." (.mm) PER SIDE ** DIMENSION DOES NOT INCLDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED." (.mm) PER SIDE. (.) TYP.. (..) 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...** (..) S

12 LT/LT TYPICAL APPLICATIO Demonstration PC oard Schematic # C*.µF EN EN V V R R R R R V OT RED G R R LT G C.µF R V OT GREEN R C.µF R V OT LE R C.µF C*.µF R R C.µF R R R G R R LT G C.µF R R R C.µF R LT/ TA *OPTIONAL RELATED PARTS PART NMER DESCRIPTION COMMENTS LT/LT MHz Video Multiplexers : and Dual : MXes with ns Switch Time LT -Input Video MX with Current Feedback Amplifier Cascadable Enable : Multiplexing LT MHz Current Feedback Amplifier V/µs Slew Rate, Shutdown Mode LT/LT/LT Low Cost Video Amplifiers Single, Dual and Quad Current Feedback Amplifiers Linear Technology Corporation McCarthy lvd., Milpitas, CA - () - FAX: () - TELEX: - fas, sn LT/TP REV A K PRINTED IN SA LINEAR TECHNOLOGY CORPORATION