Ultra-Low Noise, Low Power, Wideband Amplifier Features General Description * * * * * * * The EL2126C is an ultra-low noise, wideband amplifier that runs on half the supply current of competitive parts. It is intended for use in systems such as ultrasound imaging where a very small signal needs to be amplified by a large amount without adding significant noise. Its low power dissipation enables it to be packaged in the tiny SOT23 package, which further helps systems where many input channels create both space and power dissipation problems. Voltage noise of only 1.3nV/Hz Current noise of only 1.2pA/Hz 200V offset voltage 100MHz -3dB BW for AV=10 Very low supply current - 4.7mA SOT23 package 2.5V to 15V operation The EL2126C is stable for gains of 10 and greater and uses traditional voltage feedback. This allows the use of reactive elements in the feedback loop, a common requirement for many filter topologies. It operates from 2.5V to 15V supplies and is available in 5-pin SOT23 and 8-pin SO packages. Applications * * * * * EL2126C EL2126C Ultrasound input amplifiers Wideband instrumentation Communication equipment AGC & PLL active filters Wideband sensors The EL2126C is fabricated in Elantec's proprietary complementary bipolar process, and is specified for operation over the full -40C to +85C temperature range. Ordering Information Package Tape & Reel Outline # EL2126CW-T7 5-Pin SOT23 7" MDP0038 EL2126CW-T13 5-Pin SOT23 13" MDP0038 8-Pin SO - MDP0027 Part No EL2126CS EL2126CS-T7 8-Pin SO 7" MDP0027 EL2126CS-T13 8-Pin SO 13" MDP0027 Connection Diagrams NC 1 OUT 1 VS- 2 5 VS+ + IN+ 3 - IN+ 3 4 INEL2126C (5-Pin SOT23) IN- 2 8 NC + VS- 4 7 VS+ 6 OUT 5 NC EL2126C (8-Pin SO) March 15, 2002 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. (c) 2002 Elantec Semiconductor, Inc. EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Absolute Maximum Ratings (T A= VS+ to VSContinuous Output Current Any Input Power Dissipation 25C) 33V 40mA VS+ - 0.3V to VS- + 0.3V See Curves Operating Temperature Storage Temperature Maximum Die Junction Temperature -40C to +85C -60C to +150C +150C 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: T J = TC = TA Electrical Characteristics VS+ = +5V, VS- = -5V, TA = 25C, RF = 180, RG = 20, RL = 500 unless otherwise specified. Parameter Description Conditions Min Typ Max Unit DC Performance VOS Input Offset Voltage (SO8) 0.2 Input Offset Voltage (SOT23-5) TCVOS Offset Voltage Temperature Coefficient IB Input Bias Current IOS Input Bias Current Offset 0.06 TCIB Input Bias Current Temperature Coefficient 0.013 CIN Input Capacitance AVOL Open Loop Gain PSRR Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Positive Output Voltage Swing VOUTL Negative Output Voltage Swing No load, RF = 1k VOUTH2 Positive Output Voltage Swing RL = 100 VOUTL2 Negative Output Voltage Swing RL = 100 IOUT Output Short Circuit Current ISY Supply Current 2 mV 3 mV 17 -10 VO = -2.5V to +2.5V [1] at CMIR A A/C 2.2 pF 87 dB 80 100 dB 75 106 3.8 3.8 3.2 3.45 -4 80 dB 3.8 -3.5 [2] A 0.6 80 -4.6 No load, RF = 1k V/C -7 -3.9 V -3.2 V 5.5 mA V 100 4.7 V V mA AC Performance - RG = 20, CL = 3pF BW -3dB Bandwidth, RL = 500 100 BW 0.1dB 0.1dB Bandwidth, RL = 500 17 MHz BW 1dB 1dB Bandwidth, RL = 500 80 MHz Peaking Peaking, RL = 500 SR Slew Rate OS Overshoot, 4Vpk-pk Output Square Wave VOUT = 2VPP, measured at 20% to 80% 80 MHz 0.6 dB 110 V/s Positive 2.8 % Negative -7 % tS Settling Time to 0.1% of 1V Pulse 51 ns VN Voltage Noise Spectral Density 1.3 nV/Hz IN Current Noise Spectral Density 1.2 pA/Hz HD2 2nd Harmonic Distortion [3] -70 dBc HD3 3rd Harmonic Distortion [3] -70 dBc 1. Measured by moving the supplies from 4V to 6V 2. Pulse test only and using a 10 load 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500 and 5pF load 2 Electrical Characteristics VS+ = +15V, VS- = -15V, TA = 25C, RF = 180, RG = 20, RL = 500 unless otherwise specified. Parameter Description Conditions Min Typ Max Unit DC Performance VOS Input Offset Voltage (SO8) 0.5 Input Offset Voltage (SOT23-5) TCVOS Offset Voltage Temperature Coefficient IB Input Bias Current IOS Input Bias Current Offset 0.12 TCIB Input Bias Current Temperature Coefficient 0.016 CIN Input Capacitance AVOL Open Loop Gain PSRR Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Positive Output Voltage Swing 3 mV 3 mV 4.5 -10 [1] at CMIR VOUTL Negative Output Voltage Swing No load, RF = 1k VOUTH2 Positive Output Voltage Swing RL = 100, RF = 1k VOUTL2 Negative Output Voltage Swing RL = 100, RF = 1k IOUT Output Short Circuit Current ISY Supply Current [2] A 0.7 A A/C 2.2 pF 80 90 dB 65 80 dB 70 85 -14.6 No load, RF = 1k V/C -7 13.6 13.7 -13.8 10.2 -13.7 V V -9.5 220 5 V V 11.2 -10.3 140 dB 13.8 V mA 6 mA AC Performance - RG = 20, CL = 3pF BW -3dB Bandwidth, RL = 500 135 BW 0.1dB 0.1dB Bandwidth, RL = 500 26 MHz BW 1dB 1dB Bandwidth, RL = 500 60 MHz Peaking Peaking, RL = 500 SR Slew Rate (2.5V Square Wave, Measured 25%-75%) OS Overshoot, 4Vpk-pk Output Square Wave 130 MHz 2.1 dB 150 V/S Positive 1.6 % Negative -4.4 % TS Settling Time to 0.1% of 1V Pulse 48 ns VN Voltage Noise Spectral Density 1.4 nV/Hz IN Current Noise Spectral Density 1.1 pA/Hz HD2 2nd Harmonic Distortion [3] -72 dBc HD3 3rd Harmonic Distortion [3] -73 dBc 1. Measured by moving the supplies from 13.5V to 16.5V 2. Pulse test only and using a 10 load 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500 and 5pF load 3 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Non-Inverting Frequency Response for Various RF Non-Inverting Frequency Response for Various RF 10 10 VS=5V AV=10 CL=5pF RL=500 RF=1k 6 RF=500 Normalized Gain (dB) Normalized Gain (dB) 6 2 -2 RF=180 -6 10M VS=15V AV=10 CL=5pF RL=500 -2 RF=180 RF=100 -10 1M 100M 100M Inverting Frequency Response for Various RF 8 8 VS=5V AV=-10 CL=5pF RL=500 RF=500 RF=1k 4 RF=350 Normalized Gain (dB) Normalized Gain (dB) 10M Frequency (Hz) Inverting Frequency Response for Various RF 0 RF=200 -4 RF=100 -8 VS=15V AV=-10 CL=5pF RL=500 RF=1k RF=500 RF=350 0 RF=200 -4 RF=100 -8 -12 1M 10M -12 1M 100M Frequency (Hz) 10M 100M Frequency (Hz) Non-Inverting Frequency Response for Various Gain Non-Inverting Frequency Response for Various Gain 10 10 VS=5V RG=20 RL=500 CL=5pF 6 2 Normalized Gain (dB) 6 RF=500 2 Frequency (Hz) 4 RF=1k -6 RF=100 -10 1M Normalized Gain (dB) EL2126C EL2126C AV=10 AV=20 -2 AV=50 AV=10 2 AV =20 -2 AV=50 -6 -6 -10 1M VS=15V RG=20 RL=500 CL=5pF 10M -10 1M 100M Frequency (Hz) 10M Frequency (Hz) 4 100M Typical Performance Curves Inverting Frequency Response for Various Gain Inverting Frequency Response for Various RF 8 VS=5V CL=5pF RG=35 4 0 Normalized Gain (dB) Normalized Gain (dB) 4 8 AV=-10 -4 AV=-50 AV=-20 -8 VS=15V CL=5pF RG=20 0 AV=-10 -4 AV=-50 -8 -12 1M 10M -12 1M 100M 10M Frequency (Hz) Non-Inverting Frequency Response for Various Output Signal Levels 8 6 VO=500mVPP -4 Normalized Gain (dB) Normalized Gain (dB) 10 VS=5V CL=5pF RL=500 RF=180 AV=10 0 VO=30mV PP VO=5VPP VO=2.5V PP -8 VS=15V CL=5pF RL=500 RF=180 AV=10 10M VO=1VPP -2 VO=10V PP VO =5VPP -6 VO=2.5VPP -10 1M 100M Frequency (Hz) 10M 100M Frequency (Hz) Inverting Frequency Response for Various Output Signal Levels Inverting Frequency Response for Various Output Signal Levels 8 8 VS=5V CL=5pF RL=500 RF=350 AV=10 VO=500mVPP VO =1VPP 4 VO=30mVPP Normalized Gain (dB) Normalized Gain (dB) VO=30mVPP VO=500mVPP 2 VO =1VPP -12 1M 4 100M Frequency (Hz) Non-Inverting Frequency Response for Various Output Signal Levels 4 AV=-20 0 -4 -8 -12 1M VO=3.4V PP VO=2.5V PP 10M VS=15V CL=5pF RL=500 RF=200 AV=10 -4 -12 1M Frequency (Hz) VO=30mVPP VO =1VPP 0 -8 100M VO=500mVPP VO=3.4V PP VO=2.5V PP 10M Frequency (Hz) 5 100M EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Non-Inverting Frequency Response for Various CL Non-Inverting Frequency Response for Various CL 10 10 VS=5V RF=150 AV=10 RL=500 CL=28pF CL=11pF 2 CL=16pF CL=5pF -2 VS=15V RF=180 AV=10 RL=500 6 Normalized Gain (dB) Normalized Gain (dB) 6 CL=1pF -10 1M CL=16pF CL=5pF -2 CL=1.2pF 10M -10 1M 100M 10M 100M Frequency (Hz) Inverting Frequency Response for Various CL Inverting Frequency Response for Various CL 8 8 VS=5V RF=350 RL=500 AV=-10 CL=28pF 4 CL=16pF Normalized Gain (dB) Normalized Gain (dB) CL=11pF 2 Frequency (Hz) 4 CL=28pF -6 -6 0 CL=11pF -4 CL=5pF CL=1.2pF -8 VS=15V RF=200 RL=500 AV=-10 CL=28pF CL=16pF 0 CL=11pF -4 CL=5pF CL=1.2pF -8 -12 1M 10M -12 1M 100M Frequency (Hz) 10M Frequency (Hz) Open Loop Gain/Phase Supply Current vs Supply Voltage 100 250 Gain 60 50 40 -50 20 -150 VS=5V 0 10k 100k 1M 10M 100M -250 1G Supply Current (mA) Phase Open Loop Phase () 150 80 Open Loop Gain (dB) EL2126C EL2126C 0.6/div 0 0 Frequency (Hz) 6 1.5/div Supply Voltage (V) 100M Typical Performance Curves Bandwidth vs V s Peaking vs V s 160 3.0 VS=5V RG =20 RL=500 CL=5pF 140 VS=5V RG=20 RL=500 CL=5pF 2.5 AV=10 100 Peaking (dB) -3dB Bandwidth 120 AV=-10 80 AV =-20 60 2.0 AV=10 1.5 1.0 40 AV=-20 0.5 AV=-50 20 AV=-10 AV=50 0 0 0 2 4 6 8 10 12 14 16 0 2 4 8 12 10 14 16 Small Signal Step Response Large Signal Step Response RF=180 RG =20 6 Supply Voltage (V) VS (V) VS=5V VO=2VPP 20mV/div 0.5V/div RF=180 RG=20 VS=5V VO=100mV PP 10ns/div 10ns/div 1MHz Harmonic Distortion vs Output Swing 1MHz Harmonic Distortion vs Output Swing -40 -30 VS=5V VO=2VP-P RF=180 AV=10 RL=500 -60 VS=5V VO=2VP-P RF=180 AV=10 RL=500 -40 Harmonic Distortion (dBc) Harmonic Distortion (dBc) -50 2nd HD -70 -80 3rd HD -90 -50 2nd HD -60 -70 3rd HD -80 -90 -100 -100 0 1 2 3 4 5 6 7 8 0 VOUT (VP-P ) 5 10 15 VOUT (VP-P) 7 20 25 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Total Harmonic Distortion vs Frequency Noise vs Frequency -20 10 VS=5V VO=2VP-P IN (pA/Hz), VN (nV/Hz) -30 THD (dBc) -40 -50 -60 -70 IN, VS=5V VN , VS=15V VN, VS=5V -80 IN, VS =15V -90 1k 10k 100k 1M 10M 1 10 100M 100 1k Frequency (Hz) 100k 100M 400M Group Delay vs Frequency 70 16 50 VS= 5V, 15V, 40 VS = 30 VO =5 VS=5V RL=500 12 VP-P AV=10 VP-P 5V , V VS = 15V , 20 VO =5 Group Delay (ns) VS = 60 Settling Time (ns) 10k Frequency (Hz) Settling Time vs Accuracy O =2V P-P VO =2 VP-P 8 4 AV=-10 0 10 0 0.1 1.0 -4 1M 10.0 10M Accuracy (%) Frequency (Hz) CMRR vs Frequency PSRR vs Frequency -10 110 -30 90 -50 70 PSRR (dB) VS=5V CMRR (dB) EL2126C EL2126C -70 -90 -110 10 50 PSRR- PSRR+ 30 100 1k 10k 100k 1M 10M 10 10k 100M Frequency (Hz) 100k 1M Frequency (Hz) 8 10M 200M Typical Performance Curves Closed Loop Output Impedance vs Frequency Bandwidth and Peaking vs Temperature 120 3.5 VS=5V VS=5V 3 100 1 80 Bandwidth 2 60 1.5 1 40 Peaking 0.1 0.5 20 0.01 10k 1M 100k 0 -40 100M 10M 0 -0.5 40 0 Frequency (Hz) 80 120 160 Temperature Slew Rate vs Swing Supply Current vs Temperature 220 5.2 15VSR - 200 VS=15V 5.1 160 15VSR + IS (mA) Slew Rate (V/s) 180 140 120 5 5VSR- 100 VS=5V 4.9 5VSR+ 80 60 -1 1 3 5 7 9 11 13 4.8 -50 15 0 VOUT Swing (VPP) 50 100 150 100 150 Die Temperature (C) Offset Voltage vs Temperature CMRR vs Temperature 1 120 VS=5V 110 CMRR (dB) VOS (mV) 0 VS=15V VS=5V 100 -1 90 -2 -50 0 50 100 80 -50 150 Die Temperature (C) 0 50 Die Temperature (C) 9 Peaking (dB) 2.5 10 Bandwidth (MHz) Closed Loop Output Impedance () 100 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves PSRR vs Temperature Positive Output Swing vs Temperature 110 4.05 106 VOUTH (V) PSRR (dB) 4 VS=5V 102 98 94 3.95 VS=5V 3.9 90 VS=15V 3.85 86 82 -50 0 50 100 3.8 -50 150 0 Die Temperature (C) 50 100 150 100 150 100 150 Die Temperature (C) Positive Output Swing vs Temperature Negative Output Swing vs Temperature 13.85 -3.9 -3.95 13.8 VOUTL (V) VOUTH (V) -4 VS=15V 13.75 13.7 VS=5V -4.05 -4.1 -4.15 13.65 -4.2 13.6 -50 0 50 100 -4.25 -50 150 0 Die Temperature (C) 50 Die Temperature (C) Negative Output Swing vs Temperature Slew Rate vs Temperature -13.76 102 100 VS=5V 98 Slew Rate (V/s) -13.78 VOUTL (V) EL2126C EL2126C VS=15V -13.8 96 94 92 90 -13.82 -50 0 50 100 88 -50 150 Die Temperature (C) 0 50 Die Temperature (C) 10 Typical Performance Curves Positive Loaded Output Swing vs Temperature Slew Rate vs Temperature 155 3.52 3.5 VS=5V VS=15V VOUTH2 (V) SR (V/s) 150 145 140 3.48 3.46 VO=2VPP 135 -50 0 50 100 3.44 -50 150 0 50 100 150 Die Temperature (C) Die Temperature (C) Positive Loaded Output Swing vs Temperature Negative Loaded Output Swing vs Temperature -3.35 11.8 11.6 -3.4 VS=15V VOUTL2 (V) SR (V/s) 11.4 11.2 -3.45 -3.5 VS=5V 11 3.55 10.8 10.6 -50 0 50 100 -3.6 -50 150 0 Die Temperature (C) 18 Negative Loaded Output Swing vs Temperature -9.6 1 VOUTL2 (V) Power Dissipation (W) 1.2 VS=15V -10 -10.2 -10.4 -10.6 -50 100 150 Package Power Dissipation vs Ambient Temperature JEDEC JESD51-3 Low Effective Thermal Conductivity Test Board -9.4 -9.8 50 Die Temperature (C) 781mW 0.8 J A =1 0.6 488mW SO 8 60 C/ W SOT 23-5 JA= 256 C/W 0.4 0.2 0 0 50 100 150 0 Die Temperature (C) 25 50 75 85 100 Ambient Temperature (C) 11 125 150 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Package Power Dissipation vs Ambient Temperature JEDEC JESD51-7 High Effective Thermal Conductivity Test Board 1.8 1.6 1.4 Power Dissipation (W) EL2126C EL2126C 1.136W 1.2 1 J 0.8 543mW 0.6 0.4 0.2 A =1 SO 8 10 C/W SOT2 3-5 JA=2 30C /W 0 0 25 50 75 85 100 125 150 Ambient Temperature (C) 12 Pin Descriptions EL2126CW (5-Pin SOT23) EL2126CS (8-Pin SO) Pin Name Pin Function 1 6 VOUT Output Equivalent Circuit VS+ VOUT Circuit 1 2 4 VS- Supply 3 3 VINA+ Input VS+ VIN + VIN- VSCircuit 2 4 2 VINA- Input 5 7 VS+ Supply Reference Circuit 2 13 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Applications Information optimum performance. If a large value of RF must be used, a small capacitor in the few pF range in parallel with RF can help to reduce this ringing and peaking at the expense of reducing the bandwidth. Frequency response curves for various RF values are shown in the typical performance curves section of this data sheet. Product Description The EL2126C is an ultra-low noise, wideband monolithic operational amplifier built on Elantec's proprietary high speed complementary bipolar process. It features 1.3nV/Hz input voltage noise, 200 V typical offset voltage, and 73dB THD. It is intended for use in systems such as ultrasound imaging where very small signals are needed to be amplified. The EL2126C also has excellent DC specifications: 200V V OS , 22A IB, 0.4 A IOS , and 106dB CMRR. These specifications allow the EL2126C to be used in DC-sensitive applications such as difference amplifiers. Noise Calculations The primary application for the EL2126C is to amplify very small signals. To maintain the proper signal-tonoise ratio, it is essential to minimize noise contribution from the amplifier. Figure 2 below shows all the noise sources for all the components around the amplifier. Gain-Bandwidth Product R3 VIN The EL2126C has a gain-bandwidth product of 650MHz at 5V. For gains less than 20, higher-order poles in the amplifier's transfer function contribute to even higher closed-loop bandwidths. For example, the EL2126C has a -3dB bandwidth of 100MHz at a gain of 10 and decreases to 33MHz at gain of 20. It is important to note that the extra bandwidth at lower gain does not come at the expenses of stability. Even though the EL2126C is designed for gain 10. With external compensation, the device can also operate at lower gain settings. The RC network shown in Figure 1 reduces the feedback gain at high frequency and thus maintains the amplifier stability. R values must be less than RF divided by 9 and 1 divided by 2RC must be less than 200MHz. VR3 VN + - IN + VON VR1 R1 IN- VR2 R2 Figure 2. RF R C + VOUT V is the amplifier input voltage noise I + is the amplifier positive input current noise I - is the amplifier negative input current noise V is the thermal noise associated with each resistor: N VIN N Figure 1. N RX Choice of Feedback Resistor, RF V RX = The feedback resistor forms a pole with the input capacitance. As this pole becomes larger, phase margin is reduced. This increases ringing in the time domain and peaking in the frequency domain. Therefore, RF has some maximum value which should not be exceeded for 4 kTRx where: - k is Boltzmann's constant = 1.380658 x 10 - T is temperature in degrees Kelvin (273+ C) -23 14 The total noise due to the amplifier seen at the output of the amplifier can be calculated by using the following equation: VON = BW x 2 VN 2 R 1 2 R 1 2 R 1 2 R 1 2 2 2 2 x 1 + ------ + I N- x R 1 + IN+ x R 3 x 1 + ------ + 4 x K x T x R1 + 4 x K x T x R2 x ------ + 4 x K x T x R 3 x 1 + ------ R 2 R 2 R2 R 2 As the above equation shows, to keep noise at a minimum, small resistor values should be used. At higher amplifier gain configuration where R2 is reduced, the noise due to IN-, R 2, and R 1 decreases and the noise caused by IN+, VN, and R3 starts to dominate. Because noise is summed in a root-mean-squares method, noise sources smaller than 25% of the largest noise source can be ignored. This can greatly simplify the formula and make noise calculation much easier to calculate. Ground plane construction is highly recommended. Lead lengths should be kept as short as possible. The power supply pins must be closely bypassed to reduce the risk of oscillation. The combination of a 4.7F tantalum capacitor in parallel with 0.1F ceramic capacitor has been proven to work well when placed at each supply pin. For single supply operation, where pin 4 (VS-) is connected to the ground plane, a single 4.7F tantalum capacitor in parallel with a 0.1 F ceramic capacitor across pins 7 (VS+) and pin 4 (VS-) will suffice. Output Drive Capability For good AC performance, parasitic capacitance should be kept to a minimum. Ground plane construction again should be used. Small chip resistors are recommended to minimize series inductance. Use of sockets should be avoided since they add parasitic inductance and capacitance which will result in additional peaking and overshoot. The EL2126C is designed to drive low impedance load. It can easily drive 6V P-P signal into a 100 load. This high output drive capability makes the EL2126C an ideal choice for RF, IF, and video applications. Furthermore, the EL2126C is current-limited at the output, allowing it to withstand momentary short to ground. However, the power dissipation with output-shorted cannot exceed the power dissipation capability of the package. Supply Voltage Range and Single Supply Operation The EL2126C has been designed to operate with supply voltage range of 2.5V to 15V. With a single supply, the EL2126C will operate from +5V to +30V. Pins 4 and 7 are the power supply pins. The positive power supply is connected to pin 7. When used in single supply mode, pin 4 is connected to ground. When used in dual supply mode, the negative power supply is connected to pin 4. Driving Cables and Capacitive Loads Although the EL2126C is designed to drive low impedance load, capacitive loads will decreases the amplifier's phase margin. As shown in the performance curves, capacitive load can result in peaking, overshoot and possible oscillation. For optimum AC performance, capacitive loads should be reduced as much as possible or isolated with a series resistor between 5 to 20. When driving coaxial cables, double termination is always recommended for reflection-free performance. When properly terminated, the capacitance of the coaxial cable will not add to the capacitive load seen by the amplifier. As the power supply voltage decreases from +30V to +5V, it becomes necessary to pay special attention to the input voltage range. The EL2126C has an input voltage range of 0.4V from the negative supply to 1.2V from the positive supply. So, for example, on a single +5V supply, the EL2126C has an input voltage range which spans from 0.4V to 3.8V. The output range of the EL2126C is also quite large, on a +5V supply, it swings from 0.4V to 3.8V. Power Supply Bypassing And Printed Circuit Board Layout As with any high frequency devices, good printed circuit board layout is essential for optimum performance. 15 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband 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. March 15, 2002 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 warrant y 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 16 Printed in U.S.A.