Ultra-Low Noise, Low Power, Wideband Amplifier ® Features General Description • • • • • • • The EL2125C 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 SOT-23 package, which further helps systems where many input channels create both space and power dissipation problems. Voltage noise of only 0.83nV/√Hz Current noise of only 2.4pA/√Hz 200µV offset voltage 175MHz -3dB BW for AV=10 Low supply current - 10mA SOT-23 package available ±2.5V to ±15V operation The EL2125C 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 the 5-pin SOT-23 and 8-pin SO packages. Applications • • • • • EL2125C EL2125C ® Ultrasound input amplifiers Wideband instrumentation Communication equipment AGC & PLL active filters Wideband sensors The EL2125C is fabricated in Elantec’s proprietary complementary bipolar process, and is specified for operation from -45°C to +85°C. Ordering Information Package Tape & Reel Outline # EL2125CW-T7 5-Pin SOT-23* 7” MDP0038 EL2125CW-T13 5-Pin SOT-23* 13” MDP0038 8-Pin SO - MDP0027 Part No EL2125CS EL2125CS-T7 8-Pin SO 7” MDP0027 EL2125CS-T13 8-Pin SO 13” MDP0027 Connection Diagrams *EL2125CW symbol is .Fxxx where xxx represents date code NC 1 OUT 1 5 VS+ VS- 2 IN- 2 IN+ 3 + 8 NC + 7 VS+ 6 OUT - IN+ 3 4 IN- 5 NC EL2125CS (8-Pin SO) CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-ELANTEC or 408-945-1323 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Elantec ® is a registered trademark of Elantec Semiconductor, Inc. Copyright © Intersil Americas Inc. 2002. All Rights Reserved November 14, 2002 EL2125CW (5-Pin SOT-23) VS- 4 EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Absolute Maximum Ratings (T A VS+ to VSContinuous Output Current Any Input Power Dissipation = 25°C) 33V 40mA VS- - 0.3V to VS+ + 0.3V See Curves Operating Temperature Storage Temperature Maximum Die Junction Temperature -45°C to +85°C -60°C to +150°C +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 Electrical Characteristics VS = ±5V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified. Parameter Description Conditions Min Typ Max Unit 0.2 2 mV DC Performance VOS Input Offset Voltage (SO8) Input Offset Voltage (SOT23-5) 3 TCVOS Offset Voltage Temperature Coefficient IB Input Bias Current IOS Input Bias Current Offset 0.4 TCIB Input Bias Current Temperature Coefficient 0.09 CIN Input Capacitance AVOL Open Loop Gain 1.8 -30 [1] PSRR Power Supply Rejection Ratio Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Output Voltage Swing High No load, RF = 1kΩ at CMIR -22 VOUTL Output Voltage Swing Low No load, RF = 1kΩ Output Voltage Swing High RL = 100Ω VOUTL2 Output Voltage Swing Low RL = 100Ω IOUT Output Short Circuit Current pF dB 80 97 dB 80 106 IS Supply Current 3.5 3.65 -3.7 V V -3 100 10.1 V V 3.3 -3.5 80 dB 3.8 -3.87 3 [2] µA µA/°C 87 -4.6 VOUTH2 µA 2 2.2 80 CMRR mV µV/°C V mA 11 mA AC Performance - RG = 20Ω, CL = 5pF BW -3dB Bandwidth 175 BW ±0.1dB ±0.1dB Bandwidth 34 MHz MHz BW ±1dB ±1dB Bandwidth 150 MHz Peaking Peaking SR Slew Rate VOUT = 2VPP, measured at 20% to 80% OS Overshoot, 4Vpk-pk Output Square Wave 0.4 dB 185 V/µs Positive 0.6 % Negative 2.7 % 42 ns 150 tS Settling Time to 0.1% of ±1V Pulse VN Voltage Noise Spectral Density 0.83 nV/√Hz IN Current Noise Spectral Density 2.4 pA/√Hz HD2 2nd Harmonic Distortion [3] -74 dBc HD3 3rd Harmonic Distortion [4] -91 dBc 1. Measured by moving the supplies from ±4V to ±6V 2. Pulse test only 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load 2 Ultra-Low Noise, Low Power, Wideband Amplifier Electrical Characteristics VS = ±15V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω unless otherwise specified. Parameter Description Conditions Min Typ Max Unit 0.6 3 mV DC Performance VOS Input Offset Voltage (SO8) Input Offset Voltage (SOT23-5) 3 TCVOS Offset Voltage Temperature Coefficient IB Input Bias Current IOS Input Bias Current Offset 0.4 TCIB Input Bias Current Temperature Coefficient 0.08 CIN Input Capacitance AVOL Open Loop Gain 4.9 -30 [1] Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Output Voltage Swing High No load, RF = 1kΩ VOUTL Output Voltage Swing Low No load, RF = 1kΩ VOUTH2 Output Voltage Swing High RL = 100Ω VOUTL2 Output Voltage Swing Low IOUT Output Short Circuit Current IS Supply Current at CMIR -24 µA µA/°C pF 87 dB 80 97 dB 75 105 -14.6 13.35 RL = 100Ω 13.5 -13 V V -9.8 250 10.8 V V 11.6 -10.4 120 dB 13.8 -13.6 11 [2] µA 2 2.2 80 PSRR mV µV/°C V mA 12 mA AC Performance - RG = 20Ω, CL = 5pF BW -3dB Bandwidth 220 MHz BW ±0.1dB ±0.1dB Bandwidth 23 MHz BW ±1dB ±1dB Bandwidth 63 MHz Peaking Peaking 2.5 dB SR Slew Rate 225 V/µs OS Overshoot, 4Vpk-pk Output Square Wave 0.6 % tS Settling Time to 0.1% of ±1V Pulse VN Voltage Noise Spectral Density VOUT = 2VPP, measured at 20% to 80% 180 38 ns 0.95 nV/√Hz IN Current Noise Spectral Density 2.1 pA/√Hz HD2 2nd Harmonic Distortion [3] -73 dBc HD3 3rd Harmonic Distortion [4] -96 dBc 1. Measured by moving the supplies from ±13.5V to ±16.5V 2. Pulse test only 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load 3 EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Non-Inverting Frequency Response for Various RF Non-Inverting Frequency Response for Various RF 5 VS=±5V AV=10 RL=500Ω CL=5pF RF=1kΩ RF=499Ω Normalized Gain (dB) Normalized Gain (dB) 5 0 RF=180Ω VS=±15V AV=10 RL=500Ω CL=5pF RF=1kΩ -5 1M RF=499Ω RF=180Ω RF=100Ω -5 1M 100M 200M 10M 10M Frequency (Hz) 100M 300M Frequency (Hz) Inverting Frequency Response for Various RF Inverting Frequency Response for Various RF 6 6 2 RF=1kΩ -2 RF=350Ω RF=499Ω RF=200Ω -6 RF=97.6Ω -10 -14 1M RF=1kΩ 2 Normalized Gain (dB) Normalized Gain (dB) RF=700Ω 0 RF=100Ω VS=±5V AV=-10 RL=560Ω CL=5pF -2 RF=200Ω -6 -10 10M 100M -14 1M 300M RF=97.6Ω VS=±15V AV=-10 RL=500Ω CL=5pF 10M 100M 300M Frequency (Hz) Non-Inverting Frequency Response vs Gain Non-Inverting Frequency Response for Various Gain 5 5 Normalized Gain (dB) VS=±5V RL=500Ω CL=5pF RG=20Ω AV=10 0 AV=50 -5 1M RF=499Ω RF=350Ω Frequency (Hz) Normalized Gain (dB) EL2125C EL2125C AV=20 10M VS=±15V RL=500Ω CL=5pF RF=700Ω AV=10 0 AV=20 AV=50 -5 1M 100M 200M 10M Frequency (Hz) Frequency (Hz) 4 100M 200M Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Inverting Frequency Response vs Gain Inverting Frequency Response vs Gain 6 6 AV=-10 AV=-10 Normalized Gain (dB) Normalized Gain (dB) 2 -2 AV=-50 -6 -10 -14 1M VS=±5V RL=500Ω CL=5pF RG=35Ω 0 100M -14 1M 300M Frequency (Hz) 100M 300M Inverting Frequency Response for Various Output Signal Levels 5 6 VS=±5V AV=10 RF=180Ω RL= 500Ω CL=5pF 3mVPP 30mVPP 500mVPP 0 4VPP 2VPP 0 3.3VPP 2.5VPP 1VPP -5 1M 10M -14 1M 100M 200M VS=±5V AV=-10 RF=350Ω RL= 500Ω CL=5pF 100M 300M Frequency (Hz) Non-Inverting Frequency Response for Various CL Non-Inverting Frequency Response for Various CL 5 5 VS=±5V AV=10 RF=180Ω RL=500Ω VS=±5V AV=10 RF=700Ω RL=500Ω Normalized Gain (dB) CL=28.5pF CL=16pF 1 -1 CL=5pF CL=17pF CL=11pF 0 CL=5pF CL=1.2pF CL=1pF -3 -5 1M 1VPP 10M Frequency (Hz) 3 500mVPP 250mVPP Normalized Gain (dB) Normalized Gain (dB) 10M Frequency (Hz) Non-Inverting Frequency Response for Various Output Signal Levels Normalized Gain (dB) AV=-20 VS=±15V RL=500Ω CL=5pF RG=50Ω AV=-20 10M AV=-50 10M -5 1M 100M 200M Frequency (Hz) 10M Frequency (Hz) 5 100M 200M EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Inverting Frequency Response for Various CL Inverting Frequency Response for Various CL 6 6 CL=29.4pF CL=29.4pF 2 Normalized Gain (dB) Normalized Gain (dB) CL=16.4pF 0 CL=11.4pF CL=5.1pF -14 1M CL=1.2pF VS=±5V AV=10 RF=350Ω RL=500Ω CL=16.4pF -2 CL=11.4pF CL=5.1pF -6 CL=1.2pF -10 10M 100M -14 1M 300M VS=±15V AV=10 RF=500Ω RL=500Ω 10M 100M 300M 12 15 Frequency (Hz) Frequency (Hz) Open Loop Gain and Phase Supply Current vs Supply Voltage 100 250 12 Gain 150 Supply Current (mA) Phase 9.6 60 50 40 -50 20 -150 2.4 -250 400M 0 Phase (°) Open Loop Gain (dB) 80 7.2 4.8 VS=±5V 0 10k 100k 10M 1M 100M 0 6 3 Frequency (Hz) 9 Supply Voltage (±V) 3dB Bandwidth vs Supply Voltage Peaking vs Supply Voltage 250 3 AV=10 200 2.5 AV=-10 150 Peaking (dB) Bandwidth (MHz) EL2125C EL2125C 100 AV=-20 AV=20 AV=50 2 AV=10 AV=-10 1.5 1 AV=-50 50 0.5 AV=-20 0 2 4 6 8 10 12 14 AV=-50 AV=20 AV=50 0 16 2 VS (±V) 4 6 8 10 VS (±V) 6 12 14 16 Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Small Signal Step Response Small Signal Step Response VS=±15V RL=500Ω RF=180Ω AV=10 CL=5pF 20mV/div 20mV/div VS=±5V RL=500Ω RF=180Ω AV=10 CL=5pF VINx2 VO VINx2 VO 10ns/div 10ns/div Large-Signal Step Response Large-Signal Step Response VS=±15V RL=500Ω RF=180Ω AV=10 CL=5pF Output Voltage (0.5V/div) Output Voltage (0.5V/div) VS=±5V RL=500Ω RF=180Ω AV=10 CL=5pF Time (20ns/div) Time (20ns/div) 1MHz Harmonic Distortion vs Output Swing 1MHz Harmonic Distortion vs Output Swing -40 -30 VS=±5V RF=180Ω AV=10 RL=500Ω Distortion (dBc) -60 VS=±15V RF=180Ω AV=10 RL=500Ω -40 -50 Distortion (dBc) -50 2nd HD -70 -80 3rd HD -90 2nd HD -60 -70 -80 3rd HD -90 -100 -100 -110 -110 0 1 2 3 4 5 6 7 0 VOUT (VPP) 5 10 15 VOUT (VPP) 7 20 25 EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Voltage and Current Noise vs Frequency Voltage Noise (nV/√Hz), Current Noise (pA/√Hz) Total Harmonic Distortion vs Frequency -30 VS=±5V VO=2VPP AV=10 RF=180Ω RL=500Ω -40 THD (dBc) -50 -60 -70 -80 -90 1k 10k 100k 1M 10M 100M 100 10 IN, VS=±5V IN, VS=±15V VN, VS=±15V 1 VN, VS=±5V 0.1 10 100 Frequency (Hz) 1k 10k 100k Frequency (Hz) Settling Time vs Accuracy Group Delay 14 60 VS=±15V VS=±15V VO=5VPP 10 VS=±5V VO=5VPP 40 Group Delay (ns) Settling Time (ns) 50 30 VS=±5V VO=2VPP 20 VS=±15V VO=2VPP AV=20 6 2 AV=10 -2 10 -6 0 0.1 1 1 10 10 100 400 Frequency (MHz) Accuracy (%) CMRR PSRR -10 110 -30 90 -50 70 PSRR (dB) PSRRCMRR (dB) EL2125C EL2125C -70 -99 -110 10 PSRR+ 50 30 100 1k 10k 100k 1M 10M 10 10K 100M Frequency (Hz) 100K 1M 10M Frequency (Hz) 8 100M 600M Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Closed Loop Output Impedance vs Frequency Bandwidth vs Temperature 100 200 10 160 3.5 1 0.1 120 2 Peaking 1.5 80 1 40 0.01 0.5 0.001 10k 100k 1M 10M 0 -40 100M 0 40 80 120 0 160 Temperature (°C) Frequency (Hz) Slew Rate vs Swing Supply Current vs Temperature 350 13 300 15VSR- 12 250 IS (mA) Slew Rate (V/µs) 2.5 5VSR200 VS=±15V 11 10 150 5VSR+ VS=±5V 15VSR+ 100 0 5 10 15 9 -50 20 0 VOUT Swing (VPP) 50 100 150 100 150 Die Temperature (°C) Offset Voltage vs Temperature Input Bias Current vs Temperature 0 -10 VS=±5V -15 -1 IB+ (µA) VOS (mV) VS=±15V -20 -2 -25 -3 -50 0 50 100 -30 -50 150 Die Temperature (°C) 0 50 Die Temperature (°C) 9 Peaking (dB) -3dB Bandwidth (MHz) ROUT (Ω) 3 Bandwidth EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves CMRR vs Temperature PSRR vs Temperature 120 110 VS=±15V VS=±5V 100 PSRR (dB) CMRR (dB) 100 80 VS=±5V 60 -50 0 50 VS=±15V 90 100 80 -50 150 0 Die Temperature (°C) 100 150 100 150 Positive Output Swing vs Temperature 240 3.9 VO=2VPP VS=±15V 3.8 VOUTH (V) 220 SR (V/µs) 50 Die Temperature (°C) Slew Rate vs Temperature 200 3.7 VS=±5V VS=±5V 180 3.6 160 -50 0 50 100 3.5 -50 150 0 Die Temperature (°C) 50 Die Temperature (°C) Positive Output Swing vs Temperature Negative Output Swing vs Temperature 13.6 -9.75 -9.8 VS=±15V VS=±5V VOUTL (V) VOUTH (V) EL2125C EL2125C 13.5 -9.85 -9.9 13.4 -50 0 50 100 -9.95 -50 150 Die Temperature (°C) 0 50 Die Temperature (°C) 10 100 Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Negative Output Swing vs Temperature Loaded Negative Output Swing vs Temperature -13.4 -3.42 -3.44 -13.5 VOUTL2 (V) VOUTL (V) VS=±15V -3.46 VS=±5V -3.48 -13.6 -3.5 -13.7 -50 0 50 100 -3.52 -50 150 0 Die Temperature (°C) 50 100 150 Die Temperature (°C) Negative Output Swing vs Temperature Loaded Positive Output Swing vs Temperature -9.6 3.35 -9.8 VOUTH2 (V) VOUTL2 (V) -10 VS=±15V -10.2 VS=±5V 3.3 -10.4 -10.6 -10.8 -50 0 50 100 3.25 -50 150 0 Die Temperature (°C) Loaded Positive Output Swing vs Temperature 150 1.2 1 11.8 Power Dissipation (W) VS=±15V VOUTH2 (V) 100 Package Power Dissipation vs Ambient Temperature JEDEC JESD51-3 Low Effective Thermal Conductivity Test Board 12 11.6 11.4 11.2 11 -50 50 Die Temperature (°C) 781mW 0.8 θJ 0.6 488mW 0.4 0.2 A =1 SO 8 60° C /W SOT 23-5 θJA = 256 °C/W 0 0 50 100 150 0 Die Temperature (°C) 25 50 75 85 100 Ambient Temperature (°C) 11 125 150 EL2125C EL2125C 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) EL2125C EL2125C 1.136W 1.2 1 θJ A =1 0.8 543mW 0.6 0.4 0.2 SO 8 10 °C/ W SOT2 3-5 θJA =2 30°C /W 0 0 25 50 75 85 100 125 150 Ambient Temperature (°C) 12 Ultra-Low Noise, Low Power, Wideband Amplifier Pin Descriptions EL2125CW (5-Pin SOT-23) EL2125CS (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 EL2125C EL2125C EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Applications Information Product Description 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 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 the in typical performance curves section of this data sheet. The EL2125C is an ultra-low noise, wideband monolithic operational amplifier built on Elantec's proprietary high speed complementary bipolar process. It features 0.83nV/√Hz input voltage noise, 200µV 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 EL2125C also has excellent DC specifications: 200µ V VOS, 22µA IB, 0.4µA IOS, and 106dB CMRR. These specifications allow the EL2125C to be used in DC-sensitive applications such as difference amplifiers. Noise Calculations The primary application for the EL2125C 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 The EL2125C has a gain-bandwidth product of 800MHz at ±5V. For gains greater than 20, its closed-loop -3dB bandwidth is approximately equal to the gain-bandwidth product divided by the small signal gain of the circuit. For gains less than 20, higher-order poles in the amplifier's transfer function contribute to even higher closedloop bandwidths. For example, the EL2125C has a -3dB bandwidth of 175MHz at a gain of 10 and decreases to 40MHz 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 EL2125C 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 2πRC must be less than 400MHz. R3 VIN + - VON VR1 R1 IN - VR2 R2 Figure 2. VN is the amplifier input voltage noise IN+ is the amplifier positive input current noise IN- is the amplifier negative input current noise R C VN IN+ RF + VR3 VRX is the thermal noise associated with each resistor: VOUT VIN V RX = 4kTRx where: Figure 1. - k is Boltzmann's constant = 1.380658 x 10-23 - T is temperature in degrees Kelvin (273+ °C) Choice of Feedback Resistor, RF The feedback resistor forms a pole with the input capacitance. As this pole becomes larger, phase margin is 14 Ultra-Low Noise, Low Power, Wideband Amplifier The total noise due to the amplifier seen at the output of the amplifier can be calculated by using the following equation: V ON = 2 R 1 2 R 1 2 R 1 2 2 R 1 2 2 2 2 BW × VN × 1 + ------ + IN- × R 1 + IN+ × R 3 × 1 + ------ + 4 × K × T × R 1 + 4 × K × T × R 2 × ------ + 4 × K × T × R3 × 1 + ------ R 2 R 2 R 2 R 2 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 4.7µF tantalum capacitor in parallel with 0.1µF 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 4.7µF tantalum capacitor in parallel with a 0.1µ F ceramic capacitor across pins 7 (VS+) and pin 4 (VS-) will suffice. 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-, R2, and R1 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. 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 EL2125C is designed to drive low impedance load. It can easily drive 6VP-P signal into a 100Ω load. This high output drive capability makes the EL2125C an ideal choice for RF, IF, and video applications. Furthermore, the EL2125C 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 EL2125C has been designed to operate with supply voltage range of ±2.5V to ±15V. With a single supply, the EL2125C 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 EL2125C is designed to drive low impedance load, capacitive loads will decreases the amplifier's phase margin. As shown the 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 5Ω to 20Ω. 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 EL2125C 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 EL2125C has an input voltage range which spans from 0.4V to 3.8V. The output range of the EL2125C is also quite large, on a +5V supply, it swings from 0.4V to 3.6V. 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 EL2125C EL2125C EL2125C EL2125C Ultra-Low Noise, Low Power, Wideband Amplifier Effective May 15, 2002, Elantec, a leader in high performance analog products, is now a part of Intersil Corporation. All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. November 14, 2002 For information regarding Intersil Corporation and its products, see www.intersil.com ® Sales Office Headquarters NORTH AMERICA Intersil Corporation 7585 Irvine Center Drive Suite 100 Irvine, CA 92618 TEL: 949-341-7000 FAX: 949-341-7123 Elantec 675 Trade Zone Blvd. Milpitas, CA 95035 TEL: 408-945-1323 800: 888-ELANTEC FAX: 408-945-9305 EUROPE Intersil Europe Sarl Avenue William Fraisse 3 1006 Lausanne Switzerland TEL: +41-21-6140560 FAX: +41-21-6140579 16 ASIA Intersil Corporation Unit 1804 18/F Guangdong Water Bldg. 83 Austin Road TST, Kowloon Hong Kong TEL: +852-2723-6339 FAX: +852-2730-1433 Printed in U.S.A.