CLC1605IST5X

Data Sheet A m p l i fy t h e H u m a n E x p e r i e n c e ® Comlinear CLC1605, CLC3605 features n 0.1dB gain flatness to 120MHz n 0.01%/0.01˚ differential gain/phase n 1.2GHz -3dB bandwidth at G = 2 n 700MHz large signal bandwidth n 2,500V/μs slew rate n 3.7nV/√Hz input voltage noise n 120mA output current n Triple offers disable n Fully specified at 5V and ±5V supplies n CLC1605: Pb-free SOT23-5 n CLC3605: Pb-free SOIC-16 applications n RGB video line drivers n High definition video driver n Video switchers and routers n ADC buffer n Active filters n High-speed instrumentation n Wide dynamic range IF amp n Radar/communication receivers Single and Triple, 1.5GHz Amplifiers Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers General Description The COMLINEAR CLC1605 (single) and CLC3605 (triple) are high-performance, current feedback amplifiers that provide 1.5GHz unity gain bandwidth, ±0.1dB gain flatness to 120MHz, and 2,500V/μs slew rate. This high performance exceeds the requirements of high-definition television (HDTV) and other multimedia applications. These COMLINEAR high-performance amplifiers also provide ample output current to drive multiple video loads. The COMLINEAR CLC1605 and CLC3605 are designed to operate from ±5V or +5V supplies. The CLC3605 offers a fast enable/disable feature to save power. While disabled, the outputs are in a high-impedance state to allow for multiplexing applications. The combination of high-speed, low-power, and excellent video performance make these amplifiers well suited for use in many general purpose, high-speed applications including high-definition video, imaging applications, and radar/communications receivers. Typical Application - Driving Dual Video Loads +Vs 75Ω Cable Input 75Ω Rf Rg 75Ω -Vs 75Ω 75Ω Cable Output A 75Ω 75Ω Cable Output B 75Ω Rev 1A Ordering Information Part Number CLC1605IST5X CLC3605ISO16X CLC3605ISO16 Package SOT23-5 SOIC-16 SOIC-16 Pb-Free Yes Yes Yes RoHS Compliant Yes Yes Yes Operating Temperature Range -40°C to +85°C -40°C to +85°C -40°C to +85°C Packaging Method Reel Reel Rail Moisture sensitivity level for all parts is MSL-1. ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com Data Sheet CLC1605 Pin Configuration CLC1605 Pin Assignments Pin No. Pin Name OUT -VS +IN -IN +VS Description Output Negative supply Positive input Negative input Positive supply 1 2 3 4 5 OUT -V S +IN 1 2 3 + 5 +VS 4 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers -IN CLC3605 Pin Configuration Pin No. Pin Name -IN1 +IN1 -VS -IN2 +IN2 -VS +IN3 -IN3 DIS3 OUT3 +VS OUT2 DIS2 +VS OUT1 DIS1 Description Negative input, channel 1 Positive input, channel 1 Negative supply Negative input, channel 2 Positive input, channel 2 Negative supply Positive input, channel 3 Negative input, channel 3 Disable pin. Enabled if pin is grounded, left floating or pulled below VON, disabled if pin is pulled above VOFF. Output, channel 3 Positive supply Output, channel 2 Disable pin. Enabled if pin is grounded, left floating or pulled below VON, disabled if pin is pulled above VOFF. Positive supply Output, channel 1 Disable pin. Enabled if pin is grounded, left floating or pulled below VON, disabled if pin is pulled above VOFF. CLC3605 Pin Configuration 1 2 3 4 -IN1 +IN1 -VS -IN2 +IN2 -VS +IN3 -IN3 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 DIS1 OUT1 +VS DIS2 OUT2 +VS OUT3 DIS3 5 6 7 8 9 10 11 12 13 14 15 16 Rev 1A Disable Pin Truth Table Pin DIS *Default Open State High Disabled Low* Enabled ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 2 Data Sheet Absolute Maximum Ratings The safety of the device is not guaranteed when it is operated above the “Absolute Maximum Ratings”. The device should not be operated at these “absolute” limits. Adhere to the “Recommended Operating Conditions” for proper device function. The information contained in the Electrical Characteristics tables and Typical Performance plots reflect the operating conditions noted on the tables and plots. Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Parameter Supply Voltage Input Voltage Range Continuous Output Current Min 0 -Vs -0.5V Max 14 +Vs +0.5V 120 Unit V V mA Reliability Information Parameter Junction Temperature Storage Temperature Range Lead Temperature (Soldering, 10s) Package Thermal Resistance 5-Lead SOT23 16-Lead SOIC Notes: Package thermal resistance (qJA), JDEC standard, multi-layer test boards, still air. Min -65 Typ Max 150 150 260 Unit °C °C °C °C/W °C/W 221 68 ESD Protection Product Human Body Model (HBM) Charged Device Model (CDM) SOT23-5 2kV 1kV SOIC-16 2kV 1kV Recommended Operating Conditions Parameter Operating Temperature Range Supply Voltage Range Min -40 4.5 Typ Max +85 12 Unit °C V Rev 1A ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 3 Data Sheet Electrical Characteristics at +5V TA = 25°C, Vs = +5V, Rf = Rg =330Ω, RL = 150Ω to VS/2, G = 2; unless otherwise noted. symbol UGBW BWSS BWLS BW0.1dBSS BW0.1dBLS tR, tF tS OS SR HD2 HD3 THD DG DP IP3 SFDR en in XTALK VIO dVIO Ibn dIbn Ibi dIbi PSRR IS TON TOFF OFFIOS VOFF VON ISD parameter Unity Gain Bandwidth -3dB Bandwidth Large Signal Bandwidth 0.1dB Gain Flatness 0.1dB Gain Flatness Rise and Fall Time Settling Time to 0.1% Overshoot Slew Rate 2nd Harmonic Distortion 3rd Harmonic Distortion Total Harmonic Distortion Differential Gain Differential Phase Third Order Intercept Spurious Free Dynamic Range Input Voltage Noise Input Current Noise Crosstalk Input Offset Voltage Average Drift Input Bias Current - Non-Inverting Average Drift Input Bias Current - Inverting Average Drift Power Supply Rejection Ratio Supply Current Turn On Time Turn Off Time Off Isolation Power Down Input Voltage Enable Input Voltage Disable Supply Current conditions G = +1, VOUT = 0.5Vpp, Rf = 499Ω G = +2, VOUT = 0.5Vpp G = +2, VOUT = 1Vpp G = +2, VOUT = 0.5Vpp G = +2, VOUT = 1Vpp VOUT = 1V step; (10% to 90%) VOUT = 1V step VOUT = 0.2V step 2V step VOUT = 1Vpp, 5MHz VOUT = 1Vpp, 5MHz VOUT = 1Vpp, 5MHz NTSC (3.58MHz), AC-coupled, RL = 150Ω NTSC (3.58MHz), AC-coupled, RL = 150Ω VOUT = 1Vpp, 10MHz VOUT = 1Vpp, 5MHz > 1MHz > 1MHz, Inverting > 1MHz, Non-Inverting Channel-to-channel 5MHz, VOUT = 2Vpp Min typ 1250 1000 825 100 100 0.6 10 1 1350 -75 -85 74 0.04 0.01 37 61 3.7 20 30 60 0 1.6 3 7 6 20 Max units MHz Frequency Domain Response Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers MHz MHz MHz MHz ns ns % V/µs dBc dBc dB % ° dBm dBc nV/√Hz pA/√Hz pA/√Hz dB mV µV/°C µA nA/°C µA nA/°C dB mA ns ns dB V V mA kΩ Ω pF V dB www.cadeka.com Time Domain Response Distortion/Noise Response DC Performance DC per channel 58 11 23 350 Disable Characteristics - CLC3605 only Rev 1A 5MHz, VOUT = 2Vpp DIS pin, disabled if pin is pulled above VOFF DIS pin, enabled if pin is grounded, left open or pulled below VON DIS pin is pulled to VS Non-inverting Inverting 75 Disabled if DIS > 1.5V Enabled if DIS < 0.5V 0.09 150 70 1.0 1.5 to 3.5 Input Characteristics RIN CIN CMIR CMRR Input Resistance Input Capacitance Common Mode Input Range Common Mode Rejection Ratio DC 50 ©2007-2008 CADEKA Microcircuits LLC 4 Data Sheet Electrical Characteristics at +5V continued TA = 25°C, Vs = +5V, Rf = Rg =330Ω, RL = 150Ω to VS/2, G = 2; unless otherwise noted. symbol RO VOUT IOUT notes: 1. 100% tested at 25°C parameter Output Resistance Output Voltage Swing Output Current conditions Closed Loop, DC RL = 150Ω Min typ 0.1 1.5 to 3.5 ±120 Max units Ω V mA Output Characteristics Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Rev 1A ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 5 Data Sheet Electrical Characteristics at ±5V TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. symbol UGBW BWSS BWLS BW0.1dBSS BW0.1dBLS tR, tF tS OS SR HD2 HD3 THD DG DP IP3 SFDR en in XTALK VIO dVIO Ibn dIbn Ibi dIbi PSRR IS TON TOFF OFFIOS VOFF VON ISD parameter Unity Gain Bandwidth -3dB Bandwidth Large Signal Bandwidth 0.1dB Gain Flatness 0.1dB Gain Flatness Rise and Fall Time Settling Time to 0.1% Overshoot Slew Rate 2nd Harmonic Distortion 3rd Harmonic Distortion Total Harmonic Distortion Differential Gain Differential Phase Third Order Intercept Spurious Free Dynamic Range Input Voltage Noise Input Current Noise Crosstalk Input Offset Voltage (1) Average Drift Input Bias Current - Non-Inverting (1) Average Drift Input Bias Current - Inverting (1) Average Drift Power Supply Rejection Ratio (1) Supply Current (1) Turn On Time Turn Off Time Off Isolation Power Down Input Voltage Enable Input Voltage Disable Supply Current (1) conditions G = +1, VOUT = 0.5Vpp, Rf = 499Ω G = +2, VOUT = 0.5Vpp G = +2, VOUT = 2Vpp G = +2, VOUT = 0.5Vpp G = +2, VOUT = 2Vpp VOUT = 2V step; (10% to 90%) VOUT = 2V step VOUT = 0.2V step 2V step VOUT = 2Vpp, 5MHz VOUT = 2Vpp, 5MHz VOUT = 2Vpp, 5MHz NTSC (3.58MHz), AC-coupled, RL = 150Ω NTSC (3.58MHz), AC-coupled, RL = 150Ω VOUT = 2Vpp, 10MHz VOUT = 1Vpp, 5MHz > 1MHz > 1MHz, Inverting > 1MHz, Non-Inverting Channel-to-channel 5MHz Min typ 1500 1200 700 120 120 0.65 13 1 2500 -73 -85 72 0.01 0.01 42 73 3.7 20 30 60 Max units MHz Frequency Domain Response Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers MHz MHz MHz MHz ns ns % V/µs dBc dBc dB % ° dBm dBc nV/√Hz pA/√Hz pA/√Hz dB 10 40 35 mV µV/°C µA nA/°C µA nA/°C dB 18 mA ns ns dB V V 0.3 mA kΩ Ω pF V dB Time Domain Response Distortion/Noise Response DC Performance -10 -40 -35 DC per channel 40 0 1.6 19 7 6 20 60 12 35 410 5MHz, VOUT = 2Vpp DIS pin, disabled if pin is pulled above VOFF DIS pin, enabled if pin is grounded, left open or pulled below VON per channel, DIS pin is pulled to VS Non-inverting Inverting 75 Disabled if DIS > 3V Enabled if DIS < 1V 0.1 150 70 1.0 ±4.0 DC 40 55 Disable Characteristics - CLC3605 only Rev 1A Input Characteristics RIN CIN CMIR CMRR Input Resistance Input Capacitance Common Mode Input Range Common Mode Rejection Ratio (1) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 6 Data Sheet Electrical Characteristics at ±5V continued TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. symbol RO VOUT IOUT notes: 1. 100% tested at 25°C parameter Output Resistance Output Voltage Swing Output Current conditions Closed Loop, DC RL = 150Ω (1) Min typ 0.1 Max units Ω V mA Output Characteristics Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers ±3.0 ±3.8 ±280 Rev 1A ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 7 Data Sheet Typical Performance Characteristics TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. Non-Inverting Frequency Response 3 G=1 Rf = 499Ω G=1 Rf = 750Ω Inverting Frequency Response 1 0 -1 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers G = -1 G = -2 Normalized Gain (dB) Normalized Gain (dB) 0 G=2 -3 -2 -3 -4 -5 -6 -7 VOUT = 0.5Vpp 0.1 1 G = -5 G = -10 G=5 G = 10 VOUT = 0.5Vpp -6 -9 0.1 1 10 100 1000 10 100 1000 Frequency (MHz) Frequency (MHz) Frequency Response vs. CL 1 0 Frequency Response vs. RL 5 4 Normalized Gain (dB) -2 -3 -4 -5 -6 -7 0.1 1 VOUT = 0.5Vpp CL = 500pF Rs = 5Ω CL = 100pF Rs = 10Ω CL = 50pF Rs = 15Ω CL = 20pF Rs = 20Ω 10 100 1000 Normalized Gain (dB) -1 CL = 1000pF Rs = 3.3Ω 3 2 1 0 -1 -2 -3 -4 -5 -6 0.1 1 10 100 1000 VOUT = 0.5Vpp RL = 25Ω RL = 100Ω RL = 50Ω Frequency (MHz) Frequency (MHz) Frequency Response vs. VOUT 1 0 Frequency Response vs. Temperature 2 1 0 VOUT = 4Vpp Rev 1A Normalized Gain (dB) Normalized Gain (dB) -1 -2 -3 -4 -5 -6 -7 0.1 1 10 100 1000 VOUT = 1Vpp VOUT = 2Vpp -1 -2 -3 -4 -5 -6 -7 0.1 1 10 100 1000 10000 VOUT = 0.2Vpp + 25degC - 40degC + 85degC Frequency (MHz) Frequency (MHz) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 8 Data Sheet Typical Performance Characteristics TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. Non-Inverting Frequency Response at VS = 5V 3 G=1 Rf = 750Ω G=1 Rf = 499Ω Inverting Frequency Response at VS = 5V 1 0 -1 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers G = -1 G = -2 Normalized Gain (dB) Normalized Gain (dB) 0 G=2 -3 G=5 G = 10 VOUT = 0.5Vpp -9 0.1 1 10 100 1000 -2 -3 -4 -5 -6 -7 0.1 1 VOUT = 0.5Vpp G = -5 G = -10 -6 10 100 1000 Frequency (MHz) Frequency (MHz) Frequency Response vs. CL at VS = 5V 1 0 Frequency Response vs. RL at VS = 5V 3 2 Normalized Gain (dB) Normalized Gain (dB) -1 -2 -3 -4 -5 -6 -7 0.1 CL = 1000pF Rs = 3.3Ω CL = 500pF Rs = 5Ω CL = 100pF Rs = 10Ω CL = 50pF Rs = 15Ω VOUT = 0.5Vpp 1 CL = 20pF Rs = 20Ω 10 100 1000 1 0 -1 -2 -3 -4 -5 -6 0.1 1 10 100 1000 VOUT = 0.5Vpp RL = 100Ω RL = 50Ω RL = 25Ω Frequency (MHz) Frequency (MHz) Frequency Response vs. VOUT at VS = 5V 1 0 Frequency Response vs. Temperature at VS = 5V 2 1 0 Rev 1A Normalized Gain (dB) VOUT = 3Vpp Normalized Gain (dB) -1 -2 -3 -4 -5 -6 -7 0.1 1 10 -1 -2 -3 -4 -5 -6 -7 VOUT = 0.2Vpp + 85degC + 25degC - 40degC VOUT = 2Vpp VOUT = 1Vpp 100 1000 0.1 1 10 100 1000 10000 Frequency (MHz) Frequency (MHz) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 9 Data Sheet Typical Performance Characteristics - Continued TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. Gain Flatness 0.1 0 Gain Flatness at VS = 5V 0.1 0 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Normalized Gain (dB) -0.1 -0.2 -0.3 -0.4 -0.5 0.1 1 10 100 1000 VOUT = 2Vpp RL = 150Ω Rf = 330Ω Normalized Gain (dB) -0.1 -0.2 -0.3 -0.4 -0.5 0.1 1 10 100 1000 VOUT = 2Vpp RL = 150Ω Rf = 330Ω Frequency (MHz) Frequency (MHz) -3dB Bandwidth vs. VOUT 1800 1600 -3dB Bandwidth vs. VOUT at VS = 5V 1200 1100 1000 -3dB Bandwidth (MHz) -3dB Bandwidth (MHz) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 1400 1200 1000 800 600 400 200 900 800 700 600 500 400 300 200 0.0 0.5 1.0 1.5 2.0 2.5 3.0 VOUT (VPP) VOUT (VPP) Closed Loop Output Impedance vs. Frequency 10 VS = ±5.0V Input Voltage Noise 25 Input Voltage Noise (nV/√Hz) Rev 1A Output Resistance (Ω) 20 15 10 5 0 0.0001 1 0.1 0.01 10K 100K 1M 10M 100M 0.001 0.01 0.1 1 10 Frequency (Hz) Frequency (MHz) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 10 Data Sheet Typical Performance Characteristics - Continued TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. 2nd Harmonic Distortion vs. RL -55 -60 -65 RL = 150Ω 3rd Harmonic Distortion vs. RL -65 -70 -75 RL = 150Ω Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Distortion (dBc) Distortion (dBc) RL = 1kΩ VOUT = 2Vpp 0 5 10 15 20 -70 -75 -80 -85 -90 -95 -100 -80 -85 -90 -95 -100 0 5 10 15 20 RL = 1kΩ VOUT = 2Vpp Frequency (MHz) Frequency (MHz) 2nd Harmonic Distortion vs. VOUT -60 -65 -70 10MHz 3rd Harmonic Distortion vs. VOUT -70 -75 10MHz -80 -85 -90 -95 -100 RL = 100Ω 150 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 1MHz 5MHz Distortion (dBc) -75 -80 -85 -90 -95 -100 RL = 150Ω 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 1MHz 5MHz Output Amplitude (Vpp) Distortion (dBc) Output Amplitude (Vpp) CMRR vs. Frequency -25 VS = ±5.0V PSRR vs. Frequency 0 -10 -30 Rev 1A CMRR (dB) -40 -45 -50 -55 10k 100k 1M 10M 100M PSRR (dB) -35 -20 -30 -40 -50 -60 10K 100K 1M 10M 100M Frequency (Hz) Frequency (Hz) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 11 Data Sheet Typical Performance Characteristics - Continued TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. Small Signal Pulse Response 0.125 0.1 0.075 0.05 Small Signal Pulse Response at VS = 5V 2.625 2.6 2.575 2.55 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Voltage (V) 0 -0.025 -0.05 -0.075 -0.1 -0.125 0 20 40 60 80 100 120 140 160 180 200 Voltage (V) 0.025 2.525 2.5 2.475 2.45 2.425 2.4 2.375 0 20 40 60 80 100 120 140 160 180 200 Time (ns) Time (ns) Large Signal Pulse Response 2.5 2 1.5 1 Large Signal Pulse Response at VS = 5V 4 3.5 3 Voltage (V) 0 -0.5 -1 -1.5 -2 -2.5 0 20 40 60 80 100 120 140 160 180 200 Voltage (V) 0.5 2.5 2 1.5 1 0 20 40 60 80 100 120 140 160 180 200 Time (ns) Time (ns) Differential Gain & Phase AC Coupled Output 0.01 0.005 DG 0 -0.005 -0.01 -0.015 -0.02 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 DP Differential Gain & Phase DC Coupled Output 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 DG Rev 1A Diff Gain (%) / Diff Phase (°) RL = 150Ω AC coupled Diff Gain (%) / Diff Phase (°) DP RL = 150Ω DC coupled Input Voltage (V) Input Voltage (V) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 12 Data Sheet Typical Performance Characteristics - Continued TA = 25°C, Vs = ±5V, Rf = Rg =330Ω, RL = 150Ω to GND, G = 2; unless otherwise noted. Differential Gain & Phase AC Coupled Output at VS = ±2.5V 0.01 DP 0 -0.01 -0.02 -0.03 -0.04 -0.05 -0.35 -0.25 -0.15 -0.05 0.05 0.15 0.25 0.35 Differential Gain & Phase DC Coupled at VS = ±2.5V 0.02 0.01 DP Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Diff Gain (%) / Diff Phase (°) Diff Gain (%) / Diff Phase (°) 0 -0.01 -0.02 -0.03 -0.04 -0.05 -0.06 -0.07 -0.35 -0.25 -0.15 -0.05 0.05 0.15 0.25 0.35 RL = 150Ω DC coupled DG DG RL = 150Ω AC coupled Input Voltage (V) Input Voltage (V) Crosstalk vs. Frequency (CLC3605) -30 -35 -40 -45 -50 Crosstalk vs. Frequency at VS=5V (CLC3605) -30 -35 -40 -45 -50 Crosstalk (dB) -55 -60 -65 -70 -75 -80 -85 -90 -95 0.1 1 10 100 VOUT = 2Vpp Crosstalk (dB) -55 -60 -65 -70 -75 -80 -85 -90 -95 0.1 1 10 100 VOUT = 1Vpp Frequency (MHz) Frequency (MHz) Off Isolation vs. Frequency -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 -105 -110 0.1 1 10 100 VOUT = 2Vpp Off Isolation vs. Frequency at VS=5V -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 -105 -110 0.1 1 10 100 VOUT = 1Vpp Rev 1A Off Isolation (dB) Frequency (MHz) Off Isolation (dB) Frequency (MHz) ©2007-2008 CADEKA Microcircuits LLC www.cadeka.com 13 Data Sheet General Information - Current Feedback Technology Advantages of CFB Technology The CLC1605 Family of amplifiers utilize current feedback (CFB) technology to achieve superior performance. The primary advantage of CFB technology is higher slew rate performance when compared to voltage feedback (VFB) architecture. High slew rate contributes directly to better large signal pulse response, full power bandwidth, and distortion. CFB also alleviates the traditional trade-off between closed loop gain and usable bandwidth that is seen with a VFB amplifier. With CFB, the bandwidth is primarily determined by the value of the feedback resistor, Rf. By using optimum feedback resistor values, the bandwidth of a CFB amplifier remains nearly constant with different gain configurations. When designing with CFB amplifiers always abide by these basic rules: • Use the recommended feedback resistor value • Do not use reactive (capacitors, diodes, inductors, etc.) elements in the direct feedback path • Avoid stray or parasitic capacitance across feedback resistors • Follow general high-speed amplifier layout guidelines • Ensure proper precautions have been made for driving capacitive loads Ierr x1 Zo*Ierr Rf VOUT Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers VIN Rg RL VOUT VIN =− Rf Rg + 1+ 1 Rf Zo(jω ) Eq. 2 Figure 2. Inverting Gain Configuration with First Order Transfer Function CFB Technology - Theory of Operation Figure 1 shows a simple representation of a current feedback amplifier that is configured in the traditional noninverting gain configuration. Instead of having two high-impedance inputs similar to a VFB amplifier, the inputs of a CFB amplifier are connected across a unity gain buffer. This buffer has a high impedance input and a low impedance output. It can source or sink current (Ierr) as needed to force the non-inverting input to track the value of Vin. The CFB architecture employs a high gain trans-impedance stage that senses Ierr and drives the output to a value of (Zo(jω) * Ierr) volts. With the application of negative feedback, the amplifier will drive the output to a voltage in a manner which tries to drive Ierr to zero. In practice, primarily due to limitations on the value of Zo(jω), Ierr remains a small but finite value. A closer look at the closed loop transfer function (Eq.1) shows the effect of the trans-impedance, Zo(jω) on the gain of the circuit. At low frequencies where Zo(jω) is very large with respect to Rf, the second term of the equation approaches unity, allowing Rf and Rg to set the gain. At higher frequencies, the value of Zo(jω) will roll off, and the effect of the secondary term will begin to dominate. The -3dB small signal parameter specifies the frequency where the value Zo(jω) equals the value of Rf causing the gain to drop by 0.707 of the value at DC. For more information regarding current feedback amplifiers, visit www.cadeka.com for detailed application notes, such as AN-3: The Ins and Outs of Current Feedback Amplifiers. www.cadeka.com VIN Ierr x1 Zo*Ierr Rf VOUT Rev 1A RL Rg VOUT VIN = 1+ Rf Rg + 1+ 1 Rf Zo(jω ) Eq. 1 Figure 1. Non-Inverting Gain Configuration with First Order Transfer Function ©2007-2008 CADEKA Microcircuits LLC 14 Data Sheet Application Information Basic Operation Figures 3, 4, and 5 illustrate typical circuit configurations for non-inverting, inverting, and unity gain topologies for dual supply applications. They show the recommended bypass capacitor values and overall closed loop gain equations. +Vs 6.8μF CFB amplifiers can be used in unity gain configurations. Do not use the traditional voltage follower circuit, where the output is tied directly to the inverting input. With a CFB amplifier, a feedback resistor of appropriate value must be used to prevent unstable behavior. Refer to figure 5 and Table 1. Although this seems cumbersome, it does allow a degree of freedom to adjust the passband characteristics. Feedback Resistor Selection One of the key design considerations when using a CFB amplifier is the selection of the feedback resistor, Rf. Rf is used in conjunction with Rg to set the gain in the traditional non-inverting and inverting circuit configurations. Refer to figures 3 and 4. As discussed in the Current Feedback Technology section, the value of the feedback resistor has a pronounced effect on the frequency response of the circuit. Table 1, provides recommended Rf and associated Rg values for various gain settings. These values produce the optimum frequency response, maximum bandwidth with minimum peaking. Adjust these values to optimize performance for a specific application. The typical performance characteristics section includes plots that illustrate how the bandwidth is directly affected by the value of Rf at various gain settings. Gain (V/V 1 2 5 10 ±0.1dB BW (MHz) 167 120 66 38 -3dB BW (MHz) 1500 1200 385 245 Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Input + - 0.1μF Output 0.1μF RL Rf G = 1 + (Rf/Rg) Rg -Vs 6.8μF Figure 3. Typical Non-Inverting Gain Circuit +Vs 6.8μF R1 Input Rg + - 0.1μF Output 0.1μF 6.8μF -Vs RL Rf G = - (Rf/Rg) For optimum input offset voltage set R1 = Rf || Rg Rf (Ω) 499 330 330 330 Rg (Ω) 330 82.5 33 Figure 4. Typical Inverting Gain Circuit Table 1: Recommended Rf vs. Gain +Vs 6.8μF Rev 1A Input + - 0.1μF Output 0.1μF 6.8μF -Vs RL Rf G=1 Rf is required for CFB amplifiers In general, lowering the value of Rf from the recommended value will extend the bandwidth at the expense of additional high frequency gain peaking. This will cause increased overshoot and ringing in the pulse response characteristics. Reducing Rf too much will eventually cause oscillatory behavior. Increasing the value of Rf will lower the bandwidth. Lowering the bandwidth creates a flatter frequency response and improves 0.1dB bandwidth performance. This is important in applications such as video. Further increase in Rf will cause premature gain rolloff and adversely affect gain flatness. www.cadeka.com Figure 5. Typical Unity Gain (G=1) Circuit ©2007-2008 CADEKA Microcircuits LLC 15 Data Sheet Driving Capacitive Loads Increased phase delay at the output due to capacitive loading can cause ringing, peaking in the frequency response, and possible unstable behavior. Use a series resistance, RS, between the amplifier and the load to help improve stability and settling performance. Refer to Figure 6. In general, avoid adding any additional parasitic capacitance at this node. In addition, stray capacitance across the Rf resistor can induce peaking and high frequency ringing. Refer to the layout considerations section for additional information regarding high speed layout techniques. Overdrive Recovery Comlinear CLC1605, CLC3605 Single and Triple, 1.5GHz Amplifiers Input + Rf Rg Rs CL RL Output Figure 6. Addition of RS for Driving Capacitive Loads Table 2 provides the recommended RS for various capacitive loads. The recommended RS values result in