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 SOT-23 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 200µV offset voltage 100MHz -3dB BW for AV=10 Very low supply current - 4.7mA SOT-23 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 the 5-pin SOT-23 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 -40°C to +85°C temperature range. Ordering Information Package Tape & Reel Outline # EL2126CW-T7 5-Pin SOT-23* 7” MDP0038 EL2126CW-T13 5-Pin SOT-23* 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 *EL2126CW symbol is .Gxxx 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 EL2126CS (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 EL2126CW (5-Pin SOT-23) VS- 4 EL2126C EL2126C 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 -40°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, 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 0.06 TCIB Input Bias Current Temperature Coefficient 0.013 CIN Input Capacitance AVOL Open Loop Gain 17 -10 VO = -2.5V to +2.5V [1] PSRR Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Positive Output Voltage Swing No load, RF = 1kΩ VOUTL Negative Output Voltage Swing No load, RF = 1kΩ VOUTH2 Positive Output Voltage Swing RL = 100Ω VOUTL2 Negative Output Voltage Swing RL = 100Ω IOUT Output Short Circuit Current ISY Supply Current at CMIR -7 µA 0.6 µA µA/°C 2.2 pF 80 87 dB 80 100 dB 75 106 -4.6 3.8 3.2 V -3.9 V V 3.45 -3.5 80 dB 3.8 3.8 -4 [2] mV µV/°C V -3.2 100 4.7 V mA 5.5 mA AC Performance - RG = 20Ω, CL = 3pF BW -3dB Bandwidth, RL = 500Ω 100 MHz BW ±0.1dB ±0.1dB Bandwidth, RL = 500Ω 17 MHz BW ±1dB ±1dB Bandwidth, RL = 500Ω 80 MHz Peaking Peaking, RL = 500Ω 0.6 dB SR Slew Rate VOUT = 2VPP, measured at 20% to 80% 110 V/µs OS Overshoot, 4Vpk-pk Output Square Wave Positive 2.8 % Negative -7 % 80 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 10Ω load 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load 2 Ultra-Low Noise, Low Power, Wideband Amplifier Electrical Characteristics VS+ = +15V, VS- = -15V, TA = 25°C, RF = 180Ω, RG = 20Ω, RL = 500Ω 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 3 mV 3 mV 4.5 -10 [1] PSRR Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range VOUTH Positive Output Voltage Swing No load, RF = 1kΩ VOUTL Negative Output Voltage Swing No load, RF = 1kΩ VOUTH2 Positive Output Voltage Swing RL = 100Ω, RF = 1kΩ VOUTL2 Negative Output Voltage Swing RL = 100Ω, RF = 1kΩ IOUT Output Short Circuit Current ISY Supply Current at CMIR µA 0.7 µA µA/°C 2.2 pF 80 90 dB 65 80 dB 70 85 -14.6 13.6 10.2 V -13.7 V V 11.2 -10.3 140 dB 13.8 13.7 -13.8 [2] µV/°C -7 V -9.5 220 5 V mA 6 mA AC Performance - RG = 20Ω, CL = 3pF BW -3dB Bandwidth, RL = 500Ω 135 MHz BW ±0.1dB ±0.1dB Bandwidth, RL = 500Ω 26 MHz BW ±1dB ±1dB Bandwidth, RL = 500Ω 60 MHz Peaking Peaking, RL = 500Ω 2.1 dB SR Slew Rate (±2.5V Square Wave, Measured 25%-75%) 150 V/µS OS Overshoot, 4Vpk-pk Output Square Wave Positive 1.6 % Negative -4.4 % 130 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 10Ω load 3. Frequency = 1MHz, VOUT = 2Vpk-pk, into 500Ω and 5pF load 3 EL2126C EL2126C 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=500Ω RF=1kΩ 6 RF=500Ω Normalized Gain (dB) Normalized Gain (dB) 6 2 -2 RF=180Ω -6 10M VS=±15V AV=10 CL=5pF RL=500Ω -2 RF=180Ω RF=100Ω -10 1M 100M 100M Inverting Frequency Response for Various RF 8 8 VS=±5V AV=-10 CL=5pF RL=500Ω RF=500Ω RF=1kΩ 4 RF=350Ω Normalized Gain (dB) Normalized Gain (dB) 10M Frequency (Hz) Inverting Frequency Response for Various RF 0 RF=200Ω -4 RF=100Ω -8 VS=±15V AV=-10 CL=5pF RL=500Ω RF=1kΩ RF=500Ω RF=350Ω 0 RF=200Ω -4 RF=100Ω -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=20Ω RL=500Ω CL=5pF 6 2 Normalized Gain (dB) 6 RF=500Ω 2 Frequency (Hz) 4 RF=1kΩ -6 RF=100Ω -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=20Ω RL=500Ω CL=5pF 10M -10 1M 100M 10M Frequency (Hz) Frequency (Hz) 4 100M Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Inverting Frequency Response for Various Gain Inverting Frequency Response for Various RF 8 8 VS=±5V CL=5pF RG=35Ω 4 0 Normalized Gain (dB) Normalized Gain (dB) 4 AV=-10 -4 AV=-50 AV=-20 VS=±15V CL=5pF RG=20Ω 0 AV=-10 -4 AV=-50 -12 1M 10M -12 1M 100M 10M Non-Inverting Frequency Response for Various Output Signal Levels 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=500Ω RF=180Ω AV=10 0 VO=30mVPP VO=5VPP VO=2.5VPP -8 VS=±15V CL=5pF RL=500Ω RF=180Ω AV=10 10M VO=1VPP -2 VO=10VPP 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=500Ω RF=350Ω 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) Frequency (Hz) 4 AV=-20 -8 -8 0 -4 -8 -12 1M VO=3.4VPP VO=2.5VPP 10M VS=±15V CL=5pF RL=500Ω RF=200Ω AV=10 -4 -12 1M Frequency (Hz) VO=30mVPP VO=1VPP 0 -8 100M VO=500mVPP VO=3.4VPP VO=2.5VPP 10M Frequency (Hz) 5 100M EL2126C EL2126C 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=150Ω AV=10 RL=500Ω CL=28pF CL=11pF 2 CL=16pF CL=5pF -2 VS=±15V RF=180Ω AV=10 RL=500Ω 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=350Ω RL=500Ω 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=200Ω RL=500Ω 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 -250 1M 10M 100M Supply Current (mA) Phase Open Loop Phase (°) 150 80 Open Loop Gain (dB) EL2126C EL2126C 0.6/div 0 1G 0 Frequency (Hz) 6 1.5/div Supply Voltage (V) 100M Ultra-Low Noise, Low Power, Wideband Amplifier Typical Performance Curves Bandwidth vs Vs Peaking vs Vs 160 3.0 VS=±5V RG=20Ω RL=500Ω CL=5pF 140 VS=±5V RG=20Ω RL=500Ω CL=5pF 2.5 AV=10 100 Peaking (dB) -3dB Bandwidth 120 AV=-10 80 AV=-20 60 40 2.0 AV=10 1.5 1.0 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=180Ω RG=20Ω 6 ±Supply Voltage (V) ±VS (V) VS=±5V VO=2VPP 20mV/div 0.5V/div RF=180Ω RG=20Ω VS=±5V VO=100mVPP 10ns/div 10ns/div 1MHz Harmonic Distortion vs Output Swing 1MHz Harmonic Distortion vs Output Swing -40 -30 VS=±5V VO=2VP-P RF=180Ω AV=10 RL=500Ω -60 VS=±5V VO=2VP-P RF=180Ω AV=10 RL=500Ω -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 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 -90 1k 100k 10k 1M 10M IN, VS=±15V 1 10 100M 1k 100 Frequency (Hz) 100k 100M 400M Group Delay vs Frequency 70 16 VS =± 60 VS=±5V RL=500Ω 5V, V O =5V P-P 50 VS =± 15V, 40 VS = 30 VS =± 20 ±5V , 15V, VO = VO =2 VO =5 12 AV=10 Group Delay (ns) Settling Time (ns) 10k Frequency (Hz) Settling Time vs Accuracy VP-P 2VP -P 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 Ultra-Low Noise, Low Power, Wideband Amplifier 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 Supply Current vs Temperature Slew Rate vs Swing 5.2 220 15VSR200 VS=±15V 5.1 160 15VSR+ IS (mA) Slew Rate (V/µs) 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 (Ω) 100 EL2126C EL2126C 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/µs) -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 Ultra-Low Noise, Low Power, Wideband Amplifier 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/µs) 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) Negative Loaded Output Swing vs Temperature Positive Loaded Output Swing vs Temperature -3.35 11.8 11.6 -3.4 VS=±15V VOUTL2 (V) SR (V/µs) 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 50 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 -50 150 Package Power Dissipation vs Ambient Temperature JEDEC JESD51-3 Low Effective Thermal Conductivity Test Board -9.4 -9.8 100 Die Temperature (°C) Die Temperature (°C) 781mW 0.8 θJ A =1 0.6 488mW SO 8 60 °C/ W SOT 23-5 θJA = 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 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 θJ A =1 0.8 543mW 0.6 0.4 0.2 SO 8 10 °C/ W SOT2 3-5 θJA = 230° C/W 0 0 25 50 75 85 100 125 150 Ambient Temperature (°C) 12 Ultra-Low Noise, Low Power, Wideband Amplifier Pin Descriptions EL2126CW (5-Pin SOT-23) 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 EL2126C EL2126C Ultra-Low Noise, Low Power, Wideband Amplifier Applications Information Product Description 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. 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, 200µ 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: 200µV VOS, 22µA IB, 0.4µA 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 2πRC must be less than 200MHz. VR3 VN + - IN+ VON VR1 R1 IN - VR2 R2 Figure 2. RF R C + VOUT VN is the amplifier input voltage noise VIN IN+ is the amplifier positive input current noise IN- is the amplifier negative input current noise Figure 1. VRX is the thermal noise associated with each resistor: 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 4kTRx where: - k is Boltzmann's constant = 1.380658 x 10-23 - T is temperature in degrees Kelvin (273+ °C) 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 EL2126C 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 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 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 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 EL2126C EL2126C 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.