FEATURES DESCRIPTIO APPLICATIO S TYPICAL APPLICATIO. LT Very Low Noise, Differential Amplifier and 10MHz Lowpass Filter

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1 LT- ery Low Noise, Differential Amplifier and MHz Lowpass Filter FEATURES Programmable Differential Gain via Two External Resistors Adjustable Output Common Mode oltage Operates and Specified with,, ± Supplies.dB Ripple th Order Lowpass Filter with MHz Cutoff db S/N with Supply and P-P Output Low Distortion, P-P, Ω Load MHz: dbc nd, 9dBc rd MHz: dbc nd, dbc rd Fully Differential Inputs and Outputs SO- Package Compatible with Popular Differential Amplifier Pinouts APPLICATIO S U High Speed ADC Antialiasing and DAC Smoothing in Networking or Cellular Base Station Applications High Speed Test and Measurement Equipment Medical Imaging Drop-in Replacement for Differential Amplifiers, LTC and LT are registered trademarks of Linear Technology Corporation. DESCRIPTIO U The LT - combines a fully differential amplifier with a th order MHz lowpass filter approximating a Chebyshev frequency response. Most differential amplifiers require many precision external components to tailor gain and bandwidth. In contrast, with the LT-, two external resistors program differential gain, and the filter s MHz cutoff frequency and passband ripple are internally set. The LT- also provides the necessary level shifting to set its output common mode voltage to accommodate the reference voltage requirements of A/Ds. Using a proprietary internal architecture, the LT- integrates an antialiasing filter and a differential amplifier/ driver without compromising distortion or low noise performance. At unity gain the measured in band signal-to-noise ratio is an impressive db. At higher gains the input referred noise decreases so the part can process smaller input differential signals without significantly degrading the output signal-to-noise ratio. The LT- also features low voltage operation. The differential design provides outstanding performance for a P-P signal level while the part operates with a single supply. For similar devices with other cutoff frequencies, refer to the LT- and LT-.. TYPICAL APPLICATIO.µF R IN Ω R IN Ω LT-.µF MID OCM 9.9Ω 9.9Ω U pf A IN CM LTC GAIN = Ω/R IN µf D OUT TAa FREQUENCY (db) 9 An 9 Point FFT Spectrum INPUT IS A.MHz SINEWAE P-P f SAMPLE = MHz FREQUENCY (MHz) TAb f

2 LT- ABSOLUTE AXI U RATI GS W W W (Note ) Total Supply oltage... Operating Temperature Range (Note )... C to C Specified Temperature Range (Note )... C to C Junction Temperature... C Storage Temperature Range... C to C Lead Temperature (Soldering, sec)... C U U U W PACKAGE/ORDER I FOR ATIO IN OCM OUT TOP IEW S PACKAGE -LEAD PLASTIC SO T JMAX = C, θ JA = C/W IN MID OUT ORDER PART NUMBER LTCS- LTIS- S PART MARKING I Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes specifications that apply over the full operating temperature range, otherwise specifications are at T A = C. Unless otherwise specified S = ( =, = ), R IN = Ω, and R LOAD = k. PARAMETER CONDITIONS MIN TYP MAX UNITS Filter Gain, S = = P-P, f IN = DC to khz.. db = P-P, f IN = MHz (Gain Relative to khz).. db = P-P, f IN = MHz (Gain Relative to khz)... db = P-P, f IN = MHz (Gain Relative to khz).. db = P-P, f IN = MHz (Gain Relative to khz)... db = P-P, f IN = MHz (Gain Relative to khz) db = P-P, f IN = MHz (Gain Relative to khz) db Filter Gain, S = = P-P, f IN = DC to khz.. db = P-P, f IN = MHz (Gain Relative to khz).. db = P-P, f IN = MHz (Gain Relative to khz)... db = P-P, f IN = MHz (Gain Relative to khz)...9 db = P-P, f IN = MHz (Gain Relative to khz)... db = P-P, f IN = MHz (Gain Relative to khz) db = P-P, f IN = MHz (Gain Relative to khz) db Filter Gain, S = ± = P-P, f IN = DC to khz... db Filter Gain, R IN = Ω, S =,, ± = P-P, f IN = DC to khz.. db Filter Gain Temperature Coefficient (Note ) f IN = khz, = P-P ppm/c Noise Noise BW = khz to MHz, R IN = Ω µ RMS Distortion (Note ) MHz, P-P, R L = Ω nd Harmonic dbc rd Harmonic 9 dbc MHz, P-P, R L = Ω nd Harmonic dbc rd Harmonic dbc Differential Output Swing Measured Between Pins and S =.. P-P DIFF Pin Shorted to Pin S =..9 P-P DIFF Input Bias Current Average of Pin and Pin µa f

3 ELECTRICAL CHARACTERISTICS LT- The denotes specifications that apply over the full operating temperature range, otherwise specifications are at T A = C. Unless otherwise specified S = ( =, = ), R IN = Ω, and R LOAD = k. PARAMETER CONDITIONS MIN TYP MAX UNITS Input Referred Differential Offset R IN = Ω S = m S = m S = ± m R IN = Ω S = m S = m S = ± m Differential Offset Drift µ/ C Input Common Mode oltage (Note ) Differential Input = m P-P, S =.. R IN = Ω S =.. S = ±.. Output Common Mode oltage (Note ) Differential Output = P-P, S =.. Pin at Midsupply S =.. S = ±.. Output Common Mode Offset S = m (with respect to Pin ) S = m S = ± m Common Mode Rejection Ratio db oltage at MID (Pin ) S =... S =. MID Input Resistance... kω OCM Bias Current OCM = MID = S / S = µa S = µa Power Supply Current S =, S = 9 ma S =, S = ma S = ± ma Note : Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note : This is the temperature coefficient of the internal feedback resistors assuming a temperature independent external resistor (R IN ). Note : The input common mode voltage is the average of the voltages applied to the external resistors (R IN ). Specification guaranteed for R IN Ω. Note : Distortion is measured differentially using a differential stimulus, The input common mode voltage, the voltage at Pin, and the voltage at Pin are equal to one half of the total power supply voltage. Note : Output common mode voltage is the average of the voltages at Pins and. The output common mode voltage is equal to the voltage applied to Pin. Note : The LTC is guaranteed functional over the operating temperature range C to C. Note : The LTC is guaranteed to meet C to C specifications and is designed, characterized and expected to meet the extended temperature limits, but is not tested at C and C. The LTI is guaranteed to meet specified performance from C to C. f

4 LT- TYPICAL PERFOR A CE CHARACTERISTICS UW GAIN ( LOG DIFFOUT DIFFIN ) k Amplitude Response M M M FREQUENCY (Hz) S = GAIN = GAIN (db) Passband Gain and Group Delay S = GAIN = T A = C 9... FREQUENCY (MHz).9 GROUP DELAY (ns) G G GAIN (db) 9 Passband Gain and Group Delay S = GAIN = T A = C... FREQUENCY (MHz).9 GROUP DELAY (ns) OUTPUT IMPEDANCE (Ω). k Output Impedance vs Frequency (OUT or OUT ) M M M FREQUENCY (Hz) CMRR (db) k Common Mode Rejection Ratio S = GAIN = = P-P T A = C k M M FREQUENCY (Hz) G G G PSRR (db) 9 Power Supply Rejection Ratio DISTORTION (db) Distortion vs Frequency = P-P, S =, R L = Ω at Each Output, T A = C DIFFERENTIAL INPUT, ND HARMONIC DIFFERENTIAL INPUT, RD HARMONIC SINGLE-ENDED INPUT, ND HARMONIC SINGLE-ENDED INPUT, RD HARMONIC DISTORTION (db) Distortion vs Frequency = P-P, S = ±, R L = Ω at Each Output, T A = C DIFFERENTIAL INPUT, ND HARMONIC DIFFERENTIAL INPUT, RD HARMONIC SINGLE-ENDED INPUT, ND HARMONIC SINGLE-ENDED INPUT, RD HARMONIC S = = m P-P T A = C TO DIFFOUT k k k M M M FREQUENCY (Hz) 9. FREQUENCY (MHz) 9. FREQUENCY (MHz) G G G f

5 LT- TYPICAL PERFOR A CE CHARACTERISTICS DISTORTION (db) 9 UW Distortion vs Signal Level S =, R L = Ω at Each Output, T A = C ND HARMONIC, MHz INPUT RD HARMONIC, MHz INPUT ND HARMONIC, MHz INPUT RD HARMONIC, MHZ INPUT DISTORTION (db) 9 Distortion vs Signal Level S = ±, R L = Ω at Each Output, T A = C ND HARMONIC, MHz INPUT RD HARMONIC, MHz INPUT ND HARMONIC, MHz INPUT RD HARMONIC, MHZ INPUT DISTORTION COMPONENT (db) 9 Distortion vs Input Common Mode Level, P-P, MHz Input, x Gain, R L = Ω at Each Output, T A = C ND HARMONIC, S = RD HARMONIC, S = ND HARMONIC, S = RD HARMONIC, S = DISTORTION COMPONENT (db) 9 INPUT LEEL ( P-P ) G9 Distortion vs Input Common Mode Level,. P-P, MHz Input, x Gain, R L = Ω at Each Output, T A = C ND HARMONIC, S = RD HARMONIC, S = ND HARMONIC, S = RD HARMONIC, S = POWER SUPPLY CURRENT (ma) INPUT LEEL ( P-P ) Power Supply Current vs Power Supply oltage T A = C T A = C T A = C G m/di DIFFERENTIAL INPUT m/di INPUT COMMON MODE OLTAGE RELATIE TO PIN () Transient Response, Differential Gain = ns/di G G INPUT COMMON MODE OLTAGE RELATIE TO PIN () G 9 TOTAL SUPPLY OLTAGE () G Distortion vs Output Common Mode, P-P MHz Input, x Gain, T A = C DISTORTION COMPONENT (db) 9 ND HARMONIC, S = RD HARMONIC, S = ND HARMONIC, S = RD HARMONIC, S = ND HARMONIC, S = ± RD HARMONIC, S = ±... OUTPUT COMMON MODE OLTAGE () G f

6 LT- PI FU CTIO S U U U IN and IN (Pins, ): Input Pins. Signals can be applied to either or both input pins through identical external resistors, R IN. The DC gain from differential inputs to the differential outputs is Ω/R IN. OCM (Pin ): Is the DC Common Mode Reference oltage for the nd Filter Stage. Its value programs the common mode voltage of the differential output of the filter. Pin is a high impedance input, which can be driven from an external voltage reference, or Pin can be tied to Pin on the PC board. Pin should be bypassed with a.µf ceramic capacitor unless it is connected to a ground plane. and (Pins, ): Power Supply Pins. For a single. or supply (Pin grounded) a quality.µf ceramic bypass capacitor is required from the positive supply pin (Pin ) to the negative supply pin (Pin ). The bypass should be as close as possible to the IC. For dual supply applications, bypass Pin to ground and Pin to ground with a quality.µf ceramic capacitor. OUT and OUT (Pins, ): Output Pins. Pins and are the filter differential outputs. Each pin can drive a Ω and/or pf load to AC ground. MID (Pin ): The MID pin is internally biased at midsupply, see block diagram. For single supply operation the MID pin should be bypassed with a quality.µf ceramic capacitor to Pin. For dual supply operation, Pin can be bypassed or connected to a high quality DC ground. A ground plane should be used. A poor ground will increase noise and distortion. Pin sets the output common mode voltage of the st stage of the filter. It has a.kω impedance, and it can be overridden with an external low impedance voltage source. BLOCK DIAGRA W R IN IN OUT MID Ω OCM OP AMP k k Ω Ω OCM PROPRIETARY LOWPASS FILTER STAGE Ω Ω Ω R IN IN OCM OUT BD f

7 LT- APPLICATIO S I FOR ATIO U W U U Interfacing to the LT- The LT- requires equal external resistors, R IN, to set the differential gain to Ω/R IN. The inputs to the filter are the voltages IN and IN presented to these external components, Figure. The difference between IN and IN is the differential input voltage. The average of IN and IN is the common mode input voltage. Similarly, the voltages OUT and OUT appearing at pins and of the LT- are the filter outputs. The difference between OUT and OUT is the differential output voltage. The average of OUT and OUT is the common mode output voltage. Figure illustrates the LT- operating with a single. supply and unity passband gain; the input signal is DC coupled. The common mode input voltage is. and the differential input voltage is P-P. The common mode output voltage is. and the differential output voltage is P-P for frequencies below MHz. The common mode output voltage is determined by the voltage at pin. Since pin is shorted to pin, the output common mode is the mid-supply voltage. In addition, the common mode input voltage can be equal to the mid-supply voltage of Pin (refer to the Distortion vs Input Common Mode Level graphs in the Typical Performance Characteristics). Figure shows how to AC couple signals into the LT-. In this instance, the input is a single-ended signal. AC coupling allows the processing of single-ended or differential signals with arbitrary common mode levels. The.µF coupling capacitor and the Ω gain setting resistor form a high pass filter, attenuating signals below khz. Larger values of coupling capacitors will proportionally reduce this highpass db frequency. In Figure the LT- is providing db of gain. The gain resistor has an optional pf in parallel to improve..µf Ω LT-.µF OUT Ω t Figure F t t.µf.µf Ω Ω.µF..µF LT- F Figure m P-P (DIFF) IN t pf Ω Ω pf.µf.µf LT-.µF OUT F t Figure f

8 LT- APPLICATIO S I FOR ATIO U W U U the passband flatness near MHz. The common mode output voltage is set to. Use Figure to determine the interface between the LT- and a current output DAC. The gain, or transimpedance, is defined as A = /I IN Ω. To compute the transimpedance, use the following equation: R A = Ω R R By setting R R = Ω, the gain equation reduces to A = RΩ. The voltage at the pins of the DAC is determined by R, R, the voltage on Pin and the DAC output current (I IN or I IN ). Consider Figure with R = 9.9Ω and R = Ω. The voltage at Pin is.. The voltage at the DAC pins is given by: Figure is a laboratory setup that can be used to characterize the LT- using single-ended instruments with Ω source impedance and Ω input impedance. For a unity gain configuration the LT- requires a Ω source resistance yet the network analyzer output is calibrated for a Ω load resistance. The : transformer,.ω and Ω resistors satisfy the two constraints above. The transformer converts the single-ended source into a differential stimulus. Similarly, the output the LT- will have lower distortion with larger load resistance yet the analyzer input is typically Ω. The : turns (: impedance) transformer and the two Ω resistors of Figure, present the output of the LT- with a Ω differential load, or the equivalent of Ω to ground at each output. The impedance seen by the network analyzer input is still Ω, reducing reflections in the cabling between the transformer and analyzer input. R = I R R = m I. Ω DAC PIN IN IN R R R R I IN is I IN or I IN.The transimpedance in this example is.ω. NETWORK ANALYZER SOURCE Ω COILCRAFT TTWB- : Ω.Ω Ω..µF LT-.µF COILCRAFT TTWB-A : Ω Ω NETWORK ANALYZER INPUT Ω F CURRENT OUTPUT DAC I IN I IN R R R.µF R Figure..µF LT- F Evaluating the LT- The low impedance levels and high frequency operation of the LT- require some attention to the matching networks between the LT- and other devices. The previous examples assume an ideal (Ω) source impedance and a large (kω) load resistance. Among practical examples where impedance must be considered is the evaluation of the LT- with a network analyzer.. Figure Differential and Common Mode oltage Ranges The differential amplifiers inside the LT- contain circuitry to limit the maximum peak-to-peak differential voltage through the filter. This limiting function prevents excessive power dissipation in the internal circuitry and provides output short-circuit protection. The limiting function begins to take effect at output signal levels above P-P and it becomes noticeable above. P-P. This is illustrated in Figure ; the LTC- was configured with unity passband gain and the input of the filter was driven with a MHz signal. Because this voltage limiting takes place well before the output stage of the filter reaches the supply rails, the input/output behavior of the IC shown in Figure is relatively independent of the power supply voltage. f

9 LT- APPLICATIO S I FOR OUTPUT LEEL (db) ATIO U W U U db PASSBAND GAIN COMPRESSION POINTS RD HARMONIC C RD HARMONIC C ND HARMONIC C MHz INPUT LEEL ( P-P ) Figure MHz C MHz C ND HARMONIC C F The two amplifiers inside the LT- have independent control of their output common mode voltage (see the block diagram section). The following guidelines will optimize the performance of the filter for single supply operation. Pin must be bypassed to an AC ground with a.µf or higher capacitor. Pin can be driven from a low impedance source, provided it remains at least. above and at least. below. An internal resistor divider sets the voltage of Pin. While the internal k resistors are well matched, their absolute value can vary by ±%. This should be taken into consideration when connecting an external resistor network to alter the voltage of Pin. Pin can be shorted to Pin for simplicity. If a different common mode output voltage is required, connect Pin to a voltage source or resistor network. For and. supplies the voltage at Pin must be less than or equal to the mid supply level. For example, voltage (Pin ). on a single. supply. For power supply voltages higher than. the voltage at Pin can be set above mid supply. The voltage on Pin should not be more than below the voltage on Pin. The voltage on Pin should not be more than above the voltage on PIn. Pin is a high impedance input. The LT- was designed to process a variety of input signals including signals centered around the mid-supply voltage and signals that swing between ground and a positive voltage in a single supply system (Figure ). The range of allowable input common mode voltage (the average of and in Figure ) is determined by the power supply level and gain setting (see Electrical Characteristics ). Common Mode DC Currents In applications like Figure and Figure where the LT- not only provides lowpass filtering but also level shifts the common mode voltage of the input signal, DC currents will be generated through the DC path between input and output terminals. Minimize these currents to decrease power dissipation and distortion. Consider the application in Figure. Pin sets the output common mode voltage of the st differential amplifier inside the LT- (see the Block Diagram section) at.. Since the input common mode voltage is near, there will be approximately a total of. drop across the series combination of the internal Ω feedback resistor and the external Ω input resistor. The resulting ma common mode DC current in each input path, must be absorbed by the sources IN and IN. Pin sets the common mode output voltage of the nd differential amplifier inside the LT-, and therefore sets the common mode output voltage of the filter. Since in the example, Figure, Pin differs from Pin by., an additional.ma (.ma per side) of DC current will flow in the resistors coupling the st differential amplifier output stage to filter output. Thus, a total of.ma is used to translate the common mode voltages. A simple modification to Figure will reduce the DC common mode currents by %. If Pin is shorted to Pin the common mode output voltage of both op amp stages will be and the resulting DC current will be ma. Of course, by AC coupling the inputs of Figure, the common mode DC current can be reduced to.ma. Noise The noise performance of the LT- can be evaluated with the circuit of Figure. Given the low noise output of the LT- and the db attenuation of the transformer coupling network, it will be necessary to measure the noise floor of the spectrum analyzer and subtract the instrument noise from the filter noise measurement. f 9

10 LT- APPLICATIO S I FOR ATIO U W U U Example: With the IC removed and the Ω resistors grounded, measure the total integrated noise (e S ) of the spectrum analyzer from khz to MHz. With the IC inserted, the signal source ( ) disconnected, and the input resistors grounded, measure the total integrated noise out of the filter (e O ). With the signal source connected, set the frequency to MHz and adjust the amplitude until measures m P-P. Measure the output amplitude,, and compute the passband gain A = /. Now compute the input referred integrated noise (e IN ) as: e IN R IN R IN eo es = ( ) ( ) A...µF LT-.µF Figure Table lists the typical input referred integrated noise for various values of R IN. Figure is plot of the noise spectral density as a function of frequency for an LT- with R IN = Ω using the fixture of Figure (the instrument noise has been subtracted from the results). Table. Noise Performance INPUT REFERRED PASSBAND INTEGRATED NOISE INPUT REFERRED GAIN (/) R IN khz TO MHz NOISE dbm/hz Ω µ RMS 9 Ω µ RMS Ω µ RMS The noise at each output is comprised of a differential component and a common mode component. Using a transformer or combiner to convert the differential outputs to single-ended signal rejects the common mode Ω Ω COILCRAFT TTWB- : SPECTRUM ANALYZER INPUT Ω F SPECTRAL DENSITY (nrms/ Hz). SPECTRAL DENSITY INTEGRATED NOISE. FREQUENCY (MHz) Figure F noise and gives a true measure of the S/N achievable in the system. Conversely, if each output is measured individually and the noise power added together, the resulting calculated noise level will be higher than the true differential noise. Power Dissipation The LT- amplifiers combine high speed with largesignal currents in a small package. There is a need to ensure that the dies s junction temperature does not exceed C. The LT- package has Pin fused to the lead frame to enhance thermal conduction when connecting to a ground plane or a large metal trace. Metal trace and plated through-holes can be used to spread the heat generated by the device to the backside of the PC board. For example, on a /" FR- board with oz copper, a total of square millimeters connected to Pin of the LT- ( square millimeters on each side of the PC board) will result in a thermal resistance, θ JA, of about C/W. Without extra metal trace connected to the Table. LT- SO- Package Thermal Resistance COPPER AREA TOPSIDE BACKSIDE BOARD AREA THERMAL RESISTANCE (mm ) (mm ) (mm ) (JUNCTION-TO-AMBIENT) C/W C/W 9 C/W C/W C/W INTEGRATED NOISE (µ RMS ) f

11 LT- APPLICATIO S I FOR ATIO U W U U pin to provide a heat sink, the thermal resistance will be around C/W. Table can be used as a guide when considering thermal resistance. Junction temperature, T J, is calculated from the ambient temperature, T A, and power dissipation, P D. The power dissipation is the product of supply voltage, S, and supply current, I S. Therefore, the junction temperature is given by: T J = T A (P D θ JA ) = T A ( S I S θ JA ) where the supply current, I S, is a function of signal level, load impedance, temperature and common mode voltages. For a given supply voltage, the worst-case power dissipation occurs when the differential input signal is maximum, the common mode currents are maximum (see Applications Information regarding common mode DC currents), the load impedance is small and the ambient temperature is maximum. To compute the junction temperature, measure the supply current under these worstcase conditions, estimate the thermal resistance from Table, then apply the equation for T J. For example, using the circuit in Figure with DC differential input voltage of m, a differential output voltage of, no load resistance and an ambient temperature of C, the supply current (current into Pin ) measures.9ma. Assuming a PC board layout with a mm copper trace, the θ JA is C/W. The resulting junction temperature is: T J = T A (P D θ JA ) = (.9 ) = 9 C When using higher supply voltages or when driving small impedances, more copper may be necessary to keep T J below C. PACKAGE DESCRIPTIO U S Package -Lead Plastic Small Outline (Narrow. Inch) (Reference LTC DWG # --). BSC. ±..9.9 (..) NOTE. MIN. ±... (.9.9).. (..9) NOTE. ±. TYP RECOMMENDED SOLDER PAD LAYOUT.. (..).. (..) TYP..9 (..).. (..).. (..) NOTE: INCHES. DIMENSIONS IN (MILLIMETERS)..9 (..) TYP. DRAWING NOT TO SCALE. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED." (.mm). (.) BSC SO 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. f

12 LT- TYPICAL APPLICATIO S th Order, MHz Lowpass Filter R R R C R C = π R MHz GAIN = Ω, MAXIMUM GAIN = R.µF LT-.µF U OUT TAa GAIN (db) R = Ω C = pf k Amplitude Response DIFFERENTIAL GAIN = M M M FREQUENCY (Hz) TAb m/di DIFFERENTIAL INPUT m/di Transient Response th Order, MHz Lowpass Filter Differential Gain = ns/di TAc A WCDMA Transmit Filter (MHz Lowpass Filter with a MHz Notch) pf µh µh pf Ω R Q Ω pf Ω GAIN = db INDUCTORS ARE COILCRAFT PS-M.µF LT-.µF TAa OUT OUT GAIN (db) k Amplitude Response M M M FREQUENCY (Hz) TAb RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC - khz Linear Phase Lowpass Filter Continuous Time, SO Package, Fully Differential LTC- Low Noise,.MHz Lowpass Filter Continuous Time, SO Package, Fully Differential LT ery Low Noise, High Frequency Filter Building Block.n/ Hz Op Amp, MSOP Package, Differential Output LT ery Low Noise, th Order Building Block Lowpass and Bandpass Filter Designs Up to MHz, Differential Outputs LTC-. ery Low Noise, Differential Amplifier Adjustable Output Common Mode oltage and.mhz Lowpass Filter LTC- ery Low Noise, Differential Amplifier Adjustable Output Common Mode oltage and MHz Lowpass Filter LT/TP K PRINTED IN USA Linear Technology Corporation McCarthy Blvd., Milpitas, CA 9- () -9 FAX: () - LINEAR TECHNOLOGY CORPORATION f