200MHz Current Feedback Amplifier Features General Description • • • • The EL400C is a wide bandwidth, fast settling monolithic amplifier built using an advanced complementary bipolar process. This amplifier uses current-mode feedback to achieve more bandwidth at a given gain than conventional operational amplifiers. Designed for closedloop gains of ±1 to ±8, the EL400C has a 200MHz -3dB bandwidth (AV = +2), and 12ns settling to 0.05% while consuming only 15mA of supply current. • • • • • • 200MHz -3dB bandwidth, AV = 2 12ns settling to 0.05% VS = ±5V @ 15mA Low distortion: HD2, HD3 @ -60dBc at 20MHz Differential gain 0.02% at NTSC, PAL Differential phase 0.01° at NTSC, PAL Overload/short-circuit protected ±1 to ±8 closed-loop gain range Low cost Direct replacement for CLC400 Applications • • • • • • • • Video gain block Video distribution HDTV amplifier High-speed A/D conversion D/A I-V conversion Photodiode, CCD preamps IF processors High-speed communications EL400C EL400C The EL400C is an obvious high-performance solution for video distribution and line-driving applications. With low 15mA supply current, differential gain/phase of 0.02%/0.01°, and a minimum 50mA output drive, performance in these areas is assured. The EL400's settling to 0.05% in 12ns, low distortion, and ability to drive capacitive loads make it an ideal flash A/D driver. The wide 200MHz bandwidth and extremely linear phase allow unmatched signal fidelity. D/A systems can also benefit from the EL400C, especially if linearity and drive levels are important. Ordering Information Temp. Range Package Outline # EL400CN Part No. -40°C to +85°C 8-Pin P-DIP MDP0031 EL400CS -40°C to +85°C 8-Lead SO MDP0027 Connection Diagrams DIP and SO Package Manufactured under U.S. Patent No. 4,893,091 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. © 2001 Elantec Semiconductor, Inc. September 26, 2001 Top View EL400C EL400C 200MHz Current Feedback Amplifier Absolute Maximum Ratings (T A = 25°C) Supply Voltage (VS) Output Current ±7V Operating Temperature Lead Temperature (Soldering, 5 Seconds) Junction Temperature Storage Temperature Thermal Resistance: θJA = 95°C/W P-DIP θJA = 175°C/W SO-8 Output is short-circuit protected to ground, however, maximum reliability is obtained if IOUT does not exceed 70mA. Common-Mode Input Voltage Differential Input Voltage Power Dissipation ±VS 5V See Curves -40°C to +85°C 300°C 175°C -60°C to +150°C Important Note: All parameters having Min/Max specifications are guaranteed. Typ values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA. Open Loop DC Electrical Characteristics VS = ±5V, RL = 100Ω unless otherwise specified Parameter VOS Description Test Conditions Temp Input Offset Voltage d(VOS)/dT Average Offset Voltage Drift +IIN +Input Current Min Typ Max Unit 2.0 5.5 mV TMIN 8.7 mV TMAX 9.5 mV 25°C  All 10.0 40.0 µV/°C 25°C, TMAX 10.0 25.0 µA TMIN d(+IIN)/dT Average +Input Current Drift -IIN -Input Current   µA All 50.0 200.0 nA/°C 25°C 10.0 25.0 µA TMIN 41.0 µA TMAX 35.0 µA 200.0 nA/°C d(-IIN)/dT Average -Input Current Drift All PSRR Power Supply Rejection Ratio All 40.0 50.0 CMRR Common-Mode Rejection Ratio All 40.0 50.0 IS Supply Current—Quiescent +RIN +Input Resistance No Load 41.0 100.0 All 15.0 25°C, TMAX 100.0 TMIN 50.0 dB dB 23.0 200.0 mA kΩ kΩ CIN Input Capacitance All 0.5 2.0 pF ROUT Output Impedance (DC) All 0.1 0.2 Ω CMIR Common-Mode Input Range IOUT  Output Current VOUT Output Voltage Swing No Load VOUTL Output Voltage Swing 100Ω ROL Transimpedance 1. Measured from T MIN to TMAX. 2. Common-Mode Input Range for Rated Performance. 2 25°C, TMAX 2.0 TMIN 1.2 2.1 V V 25°C, TMAX 50.0 TMIN 35.0 70.0 mA All 3.2 3.5 25°C 3.0 3.4 V 25°C 30.0 125.0 V/mA TMIN 80.0 V/mA TMAX 140.0 V/mA mA V Closed-Loop AC Electrical Characteristics VS = ±5V, RF = 250Ω, AV = +2, RL = 100Ω unless otherwise specified Parameter Frequency Response Gain Flatness Description SSBW LSBW -3dB Bandwidth (VOUT < 5.0VPP) AV = +5 GFPL Peaking VOUT < 0.5VPP <40MHz Peaking VOUT < 0.5VPP >40MHz Rolloff VOUT < 0.5VPP <75MHz GFPH GFR LPD Time-Domain Response Test Conditions -3dB Bandwidth (VOUT < 0.5VPP) Temp Min Typ 25°C 150.0 200.0 TMIN 150.0 MHz 120.0 MHz All 35.0 25°C 50.0 0.0 25°C 0.0 TMIN, TMAX <75MHz tr1, tf1 Rise Time, Fall Time 0.5V Step tr2, tf2 Rise Time, Fall Time 5.0V Step ts1 Settling Time to 0.1% ts2 OS 25°C 0.6 dB dB TMAX 1.3 dB 1.0 ° 25°C, TMIN 0.2 ° 2.4 ns 2.9 ns All 6.5 10.0 ns 2.0V Step All 10.0 13.0 ns Settling Time to 0.05% 2.0V Step All 12.0 15.0 ns Overshoot 0.5V Step 25°C 0.0 10.0 % 25°C, TMIN HD2 2nd Harmonic Distortion at 20MHz AV = +2 2VPP All 15.0 430.0 700.0 All 1600.0 25°C -60.0 TMIN TMAX 3rd Harmonic Distortion at 20MHz 2VPP 25°C -60.0 TMIN, TMAX Video Performance dB dB 1.6 Slew Rate INV 0.5 0.7 1.2 SR NF dB dB 1.0 TMAX AV = - 2 Equivalent Input Noise 0.3 0.4 1.0 TMAX HD3 MHz TMIN TMIN, TMAX Distortion Unit MHz TMAX TMIN, TMAX Linear Phase Deviation VOUT < 0.5VPP Max Noise Floor >100kHz Integrated Noise 100kHz to 200MHz  V/µs -45.0 dBc -40.0 dBc -45.0 dBc -50.0 dBc -50.0 dBc -154.0 dBm (1Hz) TMIN -154.0 dBm (1Hz) TMAX -153.0 dBm (1Hz) 25°C  % V/µs 25°C -157.0 57.0 µV TMIN 40.0 57.0 µV TMAX 63.0 µV dG Differential Gain  NTSC/PAL 25°C 0.02 dP Differential Phase  NTSC/PAL 25°C 0.01 ° pp dG Differential Gain  30MHz 25°C 0.05 % pp dP Differential Phase  30MHz 25°C 0.05 ° pp VBW -0.1dB Bandwidth  25°C 60.0 MHz 1. Noise Tests are Performed from 5MHz to 200MHz. 2. Differential Gain/Phase Tests are RL = 100Ω. For other values of RL, see curves. 3 % pp EL400C EL400C 200MHz Current Feedback Amplifier EL400C EL400C 200MHz Current Feedback Amplifier Typical Performance Curves Non-Inverting Frequency Response Inverting Frequency Response Frequency Response for Various RLs Open-Loop Transimpedance Gain and Phase 2nd and 3rd Harmonic Distortion 2-Tone 3rd Order Intermodulation Intercept Equivalent Input Noise Settling Time Power-Supply Rejection Ratio Long-Term Settling Time 4 Common-Mode Rejection Ratio Settling Time vs Load Capacitance Recommended R S vs Load Capacitance Pulse Response AV = +2 Pulse Response AV = +2 Differential Gain and Phase (3.58MHz) Differential Gain and Phase (4.43MHz) 5 Differential Gain and Phase (30MHz) EL400C EL400C 200MHz Current Feedback Amplifier EL400C EL400C 200MHz Current Feedback Amplifier Equivalent Circuit Burn-In Circuit All Packages Use The Same Schematic. 6 Applications Information Theory of Operation measurement is then made with a 0.714V DC offset (100IRE). Differential Gain is a measure of the change in amplitude of the sine wave, and is measured in percent. Differential Phase is a measure of the change in phase, and is measured in degrees. Typically, the maximum positive and negative deviations are summed to give peak values. The EL400C has a unity gain buffer from the non-inverting input to the inverting input. The error signal of the EL400C is a current flowing into (or out of) the inverting input. A very small change in current flowing through the inverting input will cause a large change in the output voltage. This current amplification is called the transimpedance (ROL) of the EL400C [VOUT=(ROL)*(-IIN)]. Since ROL is very large, the current flowing into the inverting input in the steady-state (non-slewing) condition is very small. In general, a back terminated cable (75Ω in series at the drive end and 75Ω to ground at the receiving end) is preferred since the impedance match at both ends will absorb any reflections. However, when double-termination is used, the received signal is reduced by half; therefore a gain of 2 configuration is typically used to compensate for the attenuation. In a gain of 2 configuration, with output swing of 2V PP , with each backterminated load at 150Ω. The EL400C is capable of driving up to 4 back-terminated loads with excellent video performance. Please refer to the typical curves for more information on video performance with respect to frequency, gain, and loading. Therefore we can still use op-amp assumptions as a firstorder approximation for circuit analysis, namely that: 1. The voltage across the inputs is approximately 0V. 2. The current into the inputs is approximately 0mA. Resistor Value Selection and Optimization The value of the feedback resistor (and an internal capacitor) sets the AC dynamics of the EL400C. The nominal value for the feedback resistor is 250Ω, which is the value used for production testing. This value guarantees stability. For a given closed-loop gain the bandwidth may be increased by decreasing the feedback resistor and, conversely, the bandwidth may be decreased by increasing the feedback resistor. Capacitive Feedback The EL400C relies on its feedback resistor for proper compensation. A reduction of the impedance of the feedback element results in less stability, eventually resulting in oscillation. Therefore, circuit implementations which have capacitive feedback should not be used because of the capacitor's impedance reduction with frequency. Similarly, oscillations can occur when using the technique of placing a capacitor in parallel with the feedback resistor to compensate for shunt capacitances from the inverting input to ground. Reducing the feedback resistor too much will result in overshoot and ringing, and eventually oscillations. Increasing the feedback resistor results in a lower -3dB frequency. Attenuation at high frequency is limited by a zero in the closed-loop transfer function which results from stray capacitance between the inverting input and ground. Consequently, it is very important to keep stray capacitance to a minimum at the inverting input. Offset Adjustment Pin Output offset voltage of the EL400C can be nulled by tying a 10k potentiometer between +VS and -VS with the slider attached to pin 1. A full-range variation of the voltage at pin 1 to ±5V results in an offset voltage adjustment of at least ±10mV. For best settling performance pin 1 should be bypassed to ground with a ceramic capacitor located near to the package, even if the offset voltage adjustment feature is not being used. Differential Gain/Phase An industry-standard method of measuring the distortion of a video component is to measure the amount of differential gain and phase error it introduces. To measure these, a 40 IREPP reference signal is applied to the device with 0V DC offset (0IRE) at 3.58MHz for NTSC, 4.43MHz for PAL, and 30MHz for HDTV. A second 7 EL400C EL400C 200MHz Current Feedback Amplifier EL400C EL400C 200MHz Current Feedback Amplifier Printed Circuit Layout As with any high frequency device, good PCB layout is necessary for optimum performance. Ground plane construction is a requirement, as is good power-supply and Offset Adjust bypassing close to the package. The inverting input is sensitive to stray capacitance, therefore connections at the inverting input should be minimal, close to the package, and constructed with as little coupling the ground plane as possible. Capacitance at the output node will reduce stability, eventually resulting in peaking, and finally oscillation if the capacitance is large enough. The design of the EL400C allows a larger capacitive load than comparable products, yet there are occasions when a series resistor before the capacitance may be needed. Please refer to the graphs to determine the proper resistor value needed. 8 EL400C Macromodel * Revision A. March 1992 * Enhancements include PSRR, CMRR, and Slew Rate Limiting * Connections: +input * | -input * | | +Vsupply * | | | -Vsupply * | | | | output * | | | | | .subckt M400 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 50 l1 11 12 48nH iinp 3 0 8µA iinm 2 0 8µA * * Slew Rate Limiting * h1 13 0 vis 600 r2 13 14 1K d1 14 0 dclamp d2 0 14 dclamp * * High Frequency Pole * *e2 30 0 14 0 0.00166666666 l3 30 17 0.1µH c5 17 0 0.1pF r5 17 0 500 * * Transimpedance Stage * g1 0 18 17 0 1.0 rol 18 0 150K cdp 18 0 2.8pF * * 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 2 r8 22 6 2 ios1 7 19 2.5mA ios2 20 4 2.5mA * * Supply Current * ips 7 4 9mA * * Error Terms * ivos 0 23 5mA vxx 23 0 0V e4 24 0 3 0 1.0 e5 25 0 7 0 1.0 9 EL400C EL400C 200MHz Current Feedback Amplifier EL400C EL400C 200MHz Current Feedback Amplifier e6 26 0 4 0 1.0 r9 24 23 3K r10 25 23 1K r11 26 23 1K * * Models * .model qn npn (is=5e-15 bf=200 tf=0.5nS) .model qp pnp (is=5e-15 bf=200 tf=0.5nS) .model dclamp d(is=1e-30 ibv=0.266 bv=1.3 n=4) .ends EL400C Macromodel 10 EL400C EL400C 200MHz Current Feedback Amplifier 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. September 26, 2001 WARNING - 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 Semiconductor, Inc. 675 Trade Zone Blvd. Milpitas, CA 95035 Telephone: (408) 945-1323 (888) ELANTEC Fax: (408) 945-9305 European Office: +44-118-977-6020 Japan Technical Center: +81-45-682-5820 11 Printed in U.S.A.