150 MHz Differential Twisted Pair Driver Features General Description # Fully differential inputs, outputs, and feedback # Differential input range g 2.3V # 150 MHz 3 dB bandwidth # 800 V/ms slew rate # b 55 dB distortion at 3 MHz # b 75 dB distortion at 100 kHz # g 5V supplies or a 6V single supply # 50 mA minimum output current # Output swing (200X load) to within 1.5V of supplies (14V pk-pk differential) # Low power-11 mA typical supply current The EL2140C/2141C is a very high bandwidth amplifier whose output is in differential form, and is thus primarily targeted for applications such as driving twisted pair lines, or any application where common mode injection is likely to occur. The input signal can be in either single-ended or differential form, but the output is always in differential form. Applications # # # # # Twisted pair driver Differential line driver VGA over twisted pair ADSL/HDSL driver Single ended to differential amplification # Transmission of analog signals in a noisy environment EL2140C/2141C EL2140C/2141C On the EL2141C, two feedback inputs provide the user with the ability to set the device gain, (stable at minimum gain of two), whereas the EL2140C comes with a fixed gain of two. The output common mode level is set by the reference pin (VREF), which has a b 3 dB bandwidth of over 100 MHz. Generally, this pin is grounded, but it can be tied to any voltage reference. The transmission of ADSL/HDSL signals requires very low distortion amplification, so this amplifier was designed with this as a primary goal. The actual signal distortion levels depend upon input and output signal amplitude, as well as the output load impedance. (See distortion data inside.) Both outputs (VOUT, VOUTB) are short circuit protected to withstand temporary overload condition. Connection Diagrams EL2140C EL2141C Ordering Information Part No. Temp. Range Package Outline Ý EL2140CN b 40§ C to a 85§ C 8-pin PDIP MDP0031 EL2140CS b 40§ C to a 85§ C 8-pin SOIC MDP0027 EL2141CN b 40§ C to a 85§ C 8-pin PDIP MDP0031 EL2141CS b 40§ C to a 85§ C 8-pin SOIC MDP0027 2140-1 2140-2 October 1995, Rev A Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a ‘‘controlled document’’. Current revisions, if any, to these specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation. © 1995 Elantec, Inc. EL2140C/2141C Absolute Maximum Ratings Supply Voltage (VCC – VEE) Maximum Output Current Storage Temperature Range Operating Junction Temperaure b 40§ C to 85§ C Recommended Operating Temperature VIN, VINB, VREF VEE a 0.8V (MIN) to VCCb0.8V (MAX) g 5V VIN –VINB 0V – 12.6V g 60 mA b 65§ C to a 150§ C a 150§ C TD is 0.3in 150 MHz Differential Twisted Pair Driver Important Note: All parameters having Min/Max specifications are guaranteed. The Test Level column indicates the specific device testing actually performed during production and Quality inspection. Elantec performs most electrical tests using modern high-speed automatic test equipment, specifically the LTX77 Series system. Unless otherwise noted, all tests are pulsed tests, therefore TJ e TC e TA. Test Level I II III IV V Test Procedure 100% production tested and QA sample tested per QA test plan QCX0002. 100% production tested at TA e 25§ C and QA sample tested at TA e 25§ C , TMAX and TMIN per QA test plan QCX0002. QA sample tested per QA test plan QCX0002. Parameter is guaranteed (but not tested) by Design and Characterization Data. Parameter is typical value at TA e 25§ C for information purposes only. DC Electrical Characteristics VCC e a 5V, VEE e b5V, TA e 25§ C, VIN e 0V, RL e 200, unless otherwise specified Description Min Typ Max Test Level g 3.0 g 5.0 g 6.3 I V 11 14 I mA 10 40 I mV 6 20 I mA V kX Vsupply Supply Operating Range (VCC – VEE) IS Power Supply Current (No Load) VOS Input Referred Offset Voltage b 25 IIN Input Bias Current (VIN, VINB, VREF) b 20 ZIN Differential Input Impedance VDIFF Differential Input Range g 2.0 g 2.3 AV Voltage Gain (EL2140C) VIN e 2V pk-pk 1.95 1.985 AVOL Open Loop Voltage Gain (EL2141C) 400 2.02 75 a 4.0 Units I V I V/V V dB VCM Input Common Mode Voltage Range (EL2140C) b 2.6 I V VOUT(200) Output Voltage Swing (200X load, VOUT to VOUTB) (EL2141C) g 3.4 g 3.6 I V VOUT(100) Output Voltage Swing (100X Load, VOUT to VOUTB) (EL2141C) g 2.9 g 3.1 I V VN Input Referred Voltage Noise V nV/ SHz VREF Output Voltage Control Range (EL2140C) b 2.5 VREFOS Output Offset Relative to VREF b 60 PSRR Power Supply Rejection Ratio 60 70 I dB IOUT(min) Minimum Output Current 50 60 I mA CMRR Input Common Mode Rejection Ratio (EL2140C) VCM e g 2V 60 70 I dB ROUT (VOUT e VOUTB e 0V) Output Impedence 0.1 V X 36 2 b 25 a 3.3 I V a 60 I mV TD is 3.7in Parameter EL2140C/2141C 150 MHz Differential Twisted Pair Driver AC Electrical Characteristics Parameter Description Min @ gain of 2) Test Level Units 150 V MHz 800 V V/ms Typ Max BW(b3 dB) b 3 dB Bandwidth (EL2140C and EL2141C SR Differential Slewrate Tstl Settling Time to 1% 15 V ns GBW Gain Bandwidth Product 400 V MHz VREFBW(b3 dB) VREF b3 dB Bandwidth 130 V MHz VREFSR VREF Slewrate 100 V V/ms THDf1 Distortion at 100 kHz (Note 1) b 75 V dB dP Differential Phase 0.16 V § dG Differential Gain 0.24 V % @ @ 3.58 MHz 3.58 MHz Note 1: Distortion measurement quoted for VOUT –VOUTB e 12V pk-pk, RLOAD e 200X, Vgain e 8. Pin Description Pin No. EL2140C EL2141C 1 2 3 Pin Name Function VIN Non-inverting Input VINB Inverting Input (EL2140C only) 1 FBP Non-inverting Feedback Input. Resistor R1 must be Connected from this Pin to VOUT. (EL2141C only) 4 FBN Inverting Feedback Input. Resistor R3 must be Connected from this pin to VOUTB. (EL2141C only) 4 3 VREF Output Common-mode Control. The Common-mode Voltage of VOUT and VOUTB will Follow the Voltage on this Pin. Note that on the EL2141, this pin is also the VINB pin. 5 5 VOUTB Inverting Output 6 6 VCC Positive Supply 7 7 VEE Negative Supply 8 8 VOUT Non-inverting Output 3 TD is 2.0in VCC e a 5V, VEE e b5V, TA e 25§ C, VIN e 0V, RLOAD e 200, unless otherwise specified EL2140C/2141C 150 MHz Differential Twisted Pair Driver Typical Performance Curves IS vs Supply Voltage EL2140 Frequency Response 2140-3 2140-4 EL2141 Frequency Response vs Resistor R2 (GAIN e 2) Frequency Response vs Temperature 2140-5 2140-6 EL2141 Distortion vs Frequency (GAIN e 6, RLOAD e 200X) VIN e 2V pk/pk EL2141 Frequency Response vs Resistor R2 (GAIN e 8) 2140-7 2140-8 4 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Typical Performance Curves Ð Contd. EL2141 Output Signal and Common Mode Signal vs Frequency EL2140 CMRR vs Frequency 2140-9 2140-10 EL2140 VREF Frequency Response 2140-11 2140-12 EL2140 Small Signal Response (Note 1) Note 1: Photo shows voltages on a 100X transmission line terminated at both ends, so voltages at VOUT, VOUTB are twice the values shown. 5 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Applications Information EL2141C EL2140C 2140-14 GAIN e 2 VOUT a VOUTB e VREF 2 (common mode) 2140-13 GAIN e R1 a R2 a R3 R2 The amount of capacitance tolerated on any of these nodes in an actual application will also be dependent on the gain setting and the resistor values in the feedback network. Choice of feedback resistor There is little to be gained from choosing resistor R2 values below 400X and, in fact, it would only result in increased power dissipation and signal distortion. Above 400X, the bandwidth response will develop some peaking (for a gain of two), but substantially higher resistor R2 values may be used for higher voltage gains, such as up to 2 kX at a gain of eight before peaking will develop. R1 and R3 are selected as needed to set the voltage gain, and while R1 e R3 is suggested, the gain equation above holds for any values (see distortion for further suggestions). Distortion considerations The harmonics that these amplifiers will potentially produce are the 2nd, 3rd, 5th, and 6th. Their amplitude is application dependent. All other harmonics should be negligible by comparison. Each should be considered separately: H2 The second harmonic arises from the input stage, and the lower the applied differential signal amplitude, the lower the magnitude of the second harmonic. For practical considerations of required output signal and input noise levels, the user will end up choosing a circuit gain. Referring to Figure 1, it is best if the voltage at the negative feedback node tracks the VREF node, and the voltage at the positive feedback node tracks the VIN node respectively. This would theoretically require that R1 a R2 e R3, although the lowest distortion is found at about R3 e R1 a (0.7*R2). With this arrangement, the second harmonic should be suppressed well below the value of the third harmonic. Capacitance considerations As with many high bandwidth amplifiers, the EL2140C/2141C prefer not to drive highly capacitive loads. It is best if the capacitance on VOUT and VOUTB is kept below 10 pF if the user does not want gain peaking to develop. In addition, on the EL2141C, the two feedback nodes FBP and FBN should be laid out so as to minimize stray capacitance, else an additional pole will potentially develop in the response with possible gain peaking. 6 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Applications Information Ð Contd. H5 The fifth harmonic should always be below the third, and will not become significant until heavy load currents are drawn. Generally, it should respond to the same efforts applied to reducing the third harmonic. H3 The third harmonic should be the dominant harmonic and is primarily affected by output load current which, of course, is unavoidable. However, this should encourage the user not to waste current in the gain setting resistors, and to use values that consume only a small proportion of the load current, so long as peaking does not occur. The more load current, the worse the distortion, but depending on the frequency, it may be possible to reduce the amplifier gain so that there is more internal gain left to cancel out any distortion. H6 The sixth harmonic should not be a problem and is the result of poor power supply decoupling. While 100 nF chip capacitors may be sufficient for some applications, it would be insufficient for driving full signal swings into a twisted pair line at 100 kHz. Under these conditions, the addition of 4.7 mF tantalum capacitors would cure the problem. Typical Applications Circuits 2140-15 Figure 1. Typical Twisted Pair Application 7 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Typical Applications Circuits Ð Contd. 2140-16 Figure 2. Dual Coaxial Cable Driver 2140-17 Figure 3. Single Supply Twisted Pair Driver 8 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Typical Applications Circuits Ð Contd. 2140-18 Figure 4. Differential Line Driver with Equalization DC Gain e R1 a R2 a R3 (See Figure 5) R2 HF Gain e R1 a (R2//R4) a R3 (See Figure 5) (R2//R4) 2140-19 Figure 5 where fo e and fp e 1 2 q C 1 R2 1 2 q C 1 R4 9 EL2140C/2141C 150 MHz Differential Twisted Pair Driver Typical Applications Circuits Ð Contd. 2140-20 Figure 6. Dual Signal Transmission Circuit 10 11 BLANK EL2140C/2141C EL2140C/2141C 150 MHz Differential Twisted Pair Driver General Disclaimer Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes in the circuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. October 1995, Rev A WARNING Ð Life Support Policy Elantec, Inc. products are not authorized for and should not be used within Life Support Systems without the specific written consent of Elantec, Inc. Life Support systems are equipment intended to support or sustain life and whose failure to perform when properly used in accordance with instructions provided can be reasonably expected to result in significant personal injury or death. Users contemplating application of Elantec, Inc. products in Life Support Systems are requested to contact Elantec, Inc. factory headquarters to establish suitable terms & conditions for these applications. Elantec, Inc.’s warranty is limited to replacement of defective components and does not cover injury to persons or property or other consequential damages. Elantec, Inc. 1996 Tarob Court Milpitas, CA 95035 Telephone: (408) 945-1323 (800) 333-6314 Fax: (408) 945-9305 European Office: 44-71-482-4596 12 Printed in U.S.A.