100 MHz Current Feedback Amplifier Features General Description # Excellent differential gain and phase on g 5V to g 15V supplies # 100 MHz b 3 dB bandwidth from gains of g 1 to g 10 # 700 V/ms slew rate # 0.1 dB flatness to 20 MHz # Output disable in 50 ns - remains high impedance even when driven with large slew rates # Single a 5V supply operation # AC characteristics are lot and temperature stable # Available in small SO-8 package The EL2120C is a wideband current feedback amplifier optimized for video performance. Its 0.01% differential gain and 0.03 degree differential phase performance when at g 5V supplies exceeds the performance of other amplifiers running on g 15V supplies. Operating on g 8 to g 15V supplies reduces distortions to 0.01% and 0.01 degrees and below. The EL2120C can operate with supplies as low as g 2.5V or a single a 5V supply. Applications The EL2120C has a superior output disable function. Time to enable or disable is 50 ns and does not change markedly with temperature. Furthermore, in disable mode the output does not draw excessive currents when driven with 1000 V/ms slew rates. The output appears as a 3 pF load when disabled. # # # # # # Video gain block Residue amplifier Multiplexer Current to voltage converter Coax cable driver with gain of 2 ADC driver EL2120C EL2120C Being a current feedback design, bandwidth is a relatively constant 100 MHz over the g 1 to g 10 gain range. The EL2120C has been optimized for flat gain over frequency and all characteristics are maintained at positive unity gain. Because the input slew rate is similar to the 700 V/ms output slew rate the part makes an excellent high-speed buffer. Simplified Schematic Ordering Information Part No. Temp. Range EL2120CN 0§ C to a 75§ C EL2120CS 0§ C to a 75§ C Package Outline Ý 8-Pin P-DIP MDP0031 8-Lead SO MDP0027 Connection Diagrams P-DIP 2120 – 21 2120 – 2 Top View 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. © 1991 Elantec, Inc. January 1996 Rev E 2120 – 1 SO EL2120C 100 MHz Current Feedback Amplifier Absolute Maximum Ratings (TA e 25§ C) Voltage between V a and Vb Voltage at a IN, b IN, VOUT Voltage between a IN and b IN Voltage at /Disable Current into a IN, b IN, and /Disable Output Current Internal Power Dissipation Operating Ambient Temperature Range Operating Junction Temperature P-DIP or SO Storage Temperature Range 33V (Vb) b 0.5V to (V a ) a 0.5V g 5V (V a ) b 10V to (V a ) a 0.5V g 50 mA See Curves 0§ to 75§ C 150§ C b 65§ C to a 150§ C g 5 mA 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. Open Loop DC Electrical Characteristics Parameter Description Temp Min Typ Max Test Level Units 20 25 II II mV mV V mV/§ C VOS Input Offset Voltage VS e g 15V Full Full 4 2 DVOS/DT Input Offset Drift Full 20 IB a a VIN Input Bias Current Full 5 15 II mA IBb b VIN Input Bias Current Full 10 50 II mA CMRR Common-Mode Rejection (Note 1) Full II dB b ICMR b Input Current Common-Mode Rejection (Note 1) Full II mA/V PSRR Power Supply Rejection (Note 2) Full 80 II dB a IPSR a Input Current Power Supply Rejection (Note 2) 25§ C 0.03 V mA/V b IPSR b Input Current Power Supply Rejection (Note 2) Full 0.6 II mA/V ROL Transimpedance Full 70 140 II kX AVOL Voltage Gain Full 58 66 II dB a RIN a VIN Input Impedance 25§ C 2 V MX 2 50 55 8 65 20 5 TD is 3.2in VS e g 5V; RL e 150X, TA e 25§ C unless otherwise specified EL2120C 100 MHz Current Feedback Amplifier Open Loop DC Electrical Characteristics Ð Contd. Parameter Description Temp Min Typ Max Test Level Units VIN a VIN Range Full g 3.0 g 3.5 II V VO Output Voltage Swing Full g 3.0 g 3.5 II V ISC Output Short-Circuit Current 25§ C 100 II mA IO,DIS Output Current, Disabled Full 5 II mA VDIS,ON Disable Pin Voltage for Output Enabled Full II V VDIS,OFF Disable Pin Voltage for Output Disabled Full (V a ) b 4 II V IDIS,ON Disable Pin Current for Output Enabled Full 5 II mA IDIS,OFF Disable Pin Current for Output Disabled Full II mA IS Supply Current (VS e g 15V) Full 20 II mA Max Test Level Units 50 (V a ) b 1 1.0 17 TD is 2.7in VS e g 5V; RL e 150X, TA e 25§ C unless otherwise specified Note 1: The input is moved from b3V to a 3V. Note 2: The supplies are moved from g 5V to g 15V. Closed Loop AC Electrical Characteristics Parameter SR tS BW Description Min Slew Rate; VOUT from b3V to a 3V Measured at b2V and a 2V VS e g 15V VS e g 5V 750 550 V V V/ms V/ms Settling Time to 0.25% of a 0 to a 10V Swing; AV e a 1 with RF e 270X, RG e % , and RL e 400X 50 V ns 95 50 16 V V V MHz MHz MHz 75 35 11 V V V MHz MHz MHz 0.5 V dB Bandwidth b 3 dB g 1 dB g 0.1 dB BW @ 2.5V Typ Bandwidth at VS e g 2.5V b 3 dB g 1 dB g 0.1 dB Peaking 3 TD is 2.4in VS e g 15V; AV e a 2 (RF e RG e 270X); RL e 150X; CL e 7 pF; CINb e 2 pF; TA e 25§ C EL2120C 100 MHz Current Feedback Amplifier Closed Loop AC Electrical Characteristics Ð Contd. Parameter dG di Description Min Test Level Units 0.1 0.01 V V V % % % 0.01 0.1 0.06 V V V § § § Typ Differential Gain; DC Offset from b0.7V through a 0.7V, AC Amplitude 286 mVp–p VS e g 15V, f e 3.58 MHz VS e g 15V, f e 30 MHz VS e g 5V, f e 3.58 MHz k 0.01 Differential Phase; DC Offset from b0.7V through a 0.7V, AC Amplitude 286 mVp–p VS e g 15V, f e 3.58 MHz VS e g 15V, f e 30 MHz VS e g 5V, f e 3.58 MHz Max Typical Performance Curves AC Test Circuit 2120 – 3 Frequency Response vs RF Frequency Response vs Gain 2120 – 4 2120 – 5 4 Frequency Response vs Load 2120 – 6 TD is 2.0in VS e g 15V; AV e a 2 (RF e RG e 270X); RL e 150X; CL e 7 pF; CINb e 2 pF; TA e 25§ C EL2120C 100 MHz Current Feedback Amplifier Typical Performance Curves Ð Contd. Gain Flatness vs RF Gain Flatness vs CIN b b 3 dB Bandwidth, 0.1 dB Bandwidth, and Peaking vs Temperature at VS g 15V b 3 dB Bandwidth, 0.1 dB Bandwidth, and Peaking vs Temperature at VS g 5V b 3 dB Bandwidth, 0.1 dB Bandwidth, and Peaking vs Supply Voltage Deviation From Linear Phase vs Frequency 2120 – 7 5 EL2120C 100 MHz Current Feedback Amplifier Typical Performance Curves Ð Contd. Differential Gain vs DC Input Offset at 3.58 MHz Differential Phase vs DC Input Offset at 3.58 MHz Differential Gain vs DC Input Offset at 30 MHz Differential Phase vs DC Input Offset at 30 MHz Differential Gain and Phase vs Supply Voltage (VIN, DC from 0 to a 0.7V) Input Noise Voltage and Current 2120 – 8 6 EL2120C 100 MHz Current Feedback Amplifier Typical Performance Curves Ð Contd. Undistorted Output Swing vs Frequency Slew Rate vs Temperature 2120 – 9 Small-Signal Transient Response AV e a 2, RF e RG e 270X, RL e 150X Large-Signal Transient Response 2120 – 10 AV e a 2, RF e RG e 270X, RL e 150X, VS e g 15V Settling Time vs Swing 2120 – 11 Long Term Settling Error 2120 – 12 7 EL2120C 100 MHz Current Feedback Amplifier Typical Performance Curves Ð Contd. Enable Response for a Family of Inputs AV e a 2, RL e 150X, VS e g 5V Disable Response for a Family of Inputs 2120 – 13 AV e a 2, RL e 150X, VS e g 5V 2120 – 14 8-Pin Plastic DIP Maximum Power Dissipation vs Ambient Temperature Supply Current vs Supply Voltage 8-Lead SO Maximum Power Dissipation vs Ambient Temperature 2120 – 15 8 EL2120C 100 MHz Current Feedback Amplifier The greatest frequency response flatness (to 0.1 dB, for instance) occurs with RF e 300X to 330X. Even the moderate peaking caused by lower values of RF will cause the gain to peak out of the 0.1 dB window, and higher values of RF will cause an overcompensated response where the gain falls below the 0.1 dB level. Parasitic capacitances will generally degrade the frequency flatness. Applications Information The EL2120C represents the third generation of current-feedback amplifier design. It is designed to provide good high-frequency performance over wide supply voltage, load impedance, gain, temperature, and manufacturing lot variations. It is a well-behaved amplifier in spite of its 100 MHz bandwidth, but a few precautions should be taken to obtain maximum performance. The EL2120C should not output a continuous current above 50 mA, as stated in the ABSOLUTE MAXIMUM RATINGS table. The output current limit is set to 120 mA at a die temperature of 25§ C and reduces to 85 mA at a die temperature of 150§ C. This large current is needed to slew load capacitance and drive low impedance loads with low distortion but cannot be supported continuously. Furthermore, package dissipation capabilities cannot be met under short-circuit conditions. Current limit should not occur longer than a few seconds. The power supply pins must be well bypassed. 0.01 mF ceramic capacitors are adequate, but lead length should be kept below (/4× and a ground plane is recommended. Bypassing with 4.7 mF tantalum capacitors can improve settling characteristics, and smaller capacitors in parallel will not be needed. The lead length of sockets generally deteriorates the amplifier’s frequency response by exaggerating peaking and increasing ringing in response to transients. Short sockets cause little degradation. Load capacitance also increases ringing and peaking. Capacitance greater than 35 pF should be isolated with a series resistor. Capacitance at the VIN b terminal has a similar effect, and should be kept below 5 pF. Often, the inductance of the leads of a load capacitance will be self-resonant at frequencies from 40 MHz to 200 MHz and can cause oscillations. A resonant load can be de-Q’ed with a small series or parallel resistor. A ‘‘snubber’’ can sometimes be used to reduce resonances. This is a resistor and capacitor in series connected from output to ground. Values of 68X and 33 pF are typical. Increasing the feedback resistor can also improve frequency flatness. The output disable function of the EL2120C is optimized for video performance. While in disable mode, the feedthrough of the circuit can be modeled as a 0.2 pF capacitor from VIN a to the output. No more than g 5V can be placed between VIN a and VIN b in disable mode, but this is compatible with common video signal levels. In disabled state the output can withstand about 1000 V/ms slew rate signals impressed on it without the output transistors turning on. The /Disable pin logic level is referred to V a . With g 5V supplies, a CMOS or TTL driver with pull-up resistor will suffice. g 15V supplies require a a 14/ a 11V drive span, or a 15/ a 10V nominally. Open-collector TTL with a tapped pull-up resistor can provide these spans. The impedance of the divider should be 1k or less for optimum enable/disable speed. The VIN a pin can oscillate in the 200 MHz to 500 MHz realm if presented with a resonant or inductive source impedance. A series 27X to 68X resistor right on the VIN a pin will suppress such oscillations without affecting frequency response. The EL2120C enables in 50 ns or less. When VIN e 0, only a small switching glitch occurs at the output. When VIN is some other value, the output overshoots by about 0.7V when settling toward its new enabled value. b 3 dB bandwidth is inversely proportional to the value of feedback resistor RF. The EL2120C will tolerate values as low as 180X for a maximum bandwidth of about 140 MHz, but peaking will increase and tolerance to stray capacitance will reduce. At gains greater than 5, b 3 dB bandwidth begins to reduce, and a smaller RF can be used to maximize frequency response. 9 EL2120C 100 MHz Current Feedback Amplifier Applications Information Ð Contd. When the EL2120C disables, it turns off very rapidly for inputs of g 1V or less, and the output sags more slowly for inputs larger than this. For inputs as large as g 2.5V the output current can be absorbed by another EL2120C simultaneously enabled. Under these conditions, switching will be properly completed in 50 ns or less. The greater thermal resistance of the SO-8 package requires that the EL2120C be operated from g 10V supplies or less to maintain the 150§ C maximum die temperature over the commercial temperature range. The P-DIP package allows the full g 16.5V supply operation. Typical Applications CircuitÐA High Quality Two-Input Multiplexer Channel-to-Channel Isolation of Dual EL2120C Multiplexer Dual EL2120C Multiplexer 2120 – 17 2120 – 16 Dual EL2120C Multiplexer Switching Channels: Uncorrelated Sinewave Switched to a Family of DC Levels Dual EL2120C Multiplexer Switching Channels: a Family of DC Levels Switched to an Uncorrelated Sinewave 2120 – 19 2120 – 18 10 T EL2120C 100 MHz Current Feedback Amplifier The EL2120C Macromodel * Revision A. March 1992 * Enhancements include PSRR, CMRR, and Slew Rate Limiting a input * Connections: b input * l a Vsupply * l l b Vsupply * l l l output * l l l l * l l l l l .subckt M2120 3 2 7 4 6 * * Input Stage * e1 10 0 3 0 1.0 vis 10 9 0V h2 9 12 vxx 1.0 r1 2 11 25 l1 11 12 20nH iinp 3 0 10mA iinm 2 0 5mA r12 3 0 2Meg * * Slew Rate Limiting * h1 13 0 vis 600 r2 13 14 1K d1 14 0 dclamp s2 0 14 dclamp * * High Frequency Pole * e2 30 0 14 0 0.00166666666 15 30 17 1mH c5 17 0 0.5pF r5 17 0 600 * * Transimpedance Stage * g1 0 18 17 0 1.0 rol 18 0 140K cdp 18 0 7.9pF * * Output Stage * q1 4 18 19 qp q2 7 18 20 qn q3 7 19 21 qn q4 4 20 22 qp r7 21 6 4 r8 22 6 4 ios1 7 19 2.5mA ios2 20 4 2.5mA * * Supply * ips 7 4 10mA * * Error Terms * ivos 0 23 5mA vxx 23 0 0V e4 24 0 6 0 1.0 e5 25 0 7 0 1.0 e6 26 0 4 0 1.0 r9 24 23 562 r10 25 23 10K r11 26 23 10K * * Models * .model qn npn (is e 5eb15 bf e 500 tf e 0.1nS) .model qp pnp (is e 5eb15 bf e 500 tf e 0.1nS) .model dclamp d(is e 1eb30 ibv e 0.02 bv e 4 n e 4) .ends 11 TD is 3.8in The model does not simulate these characteristics accurately: noise non-linearities slew rate limitations temperature effects settling time manufacturing variations input or output resonances CMRR and PSRR TAB WIDE This macromodel has been developed to assist the user in simulating the EL2120C with surrounding circuitry. It was developed for the PSPICE simulator (copywritten by the Microsim corporation), and may need to be rearranged for other simulators, particularly the H operator. It approximates frequency response and small-signal transients as well, although the effects of load capacitance does not show. This model is slightly more complicated than the models used for low-frequency op-amps, but is much more accurate for AC. EL2120C EL2120C 100 MHz Current Feedback Amplifier The EL2120C Macromodel Ð Contd. 2120 – 20 EL2120 Macromodel 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. January 1996 Rev E 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.