19-0461; Rev 2; 4/97 IT K TION LUA BLE A V E ILA AVA 400MHz, Ultra-Low-Distortion Op Amps ____________________________Features ♦ High Speed: 400MHz Unity-Gain Bandwidth (MAX4108) 225MHz -3dB Bandwidth (AVCL = +2, MAX4109) 220MHz -3dB Bandwidth (AVCL = +5, MAX4308) 200MHz -3dB Bandwidth (AVCL = +10, MAX4309) ♦ 1200V/µs Slew Rate ♦ Excellent Spurious-Free Dynamic Range: -93dBc at fC = 5MHz (MAX4108) -90dBc at fC = 5MHz (MAX4109) ♦ 100MHz 0.1dB Gain Flatness (MAX4108) ♦ High Full-Power Bandwidth: 300MHz (MAX4108, VO = 2Vp-p) ♦ High Output Drive: 90mA ________________________Applications ♦ Output Short-Circuit Protected ♦ Low Differential Gain/Phase: 0.004%/0.008° High-Speed ADC/DAC Preamp RGB and Composite Video High-Performance Receivers ______________Ordering Information Pulse/RF Amplifier PART Active Filters MAX4108ESA MAX4109ESA MAX4308ESA MAX4309ESA Ultrasound Broadcast and High-Definition TV ________Typical Application Circuit TEMP. RANGE PIN-PACKAGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C 8 SO 8 SO 8 SO 8 SO __________________Pin Configuration 300Ω 300Ω TOP VIEW 53.6Ω* 10Ω MAX4109 N.C. 1 12-BIT ADC 300Ω IN- 2 IN+ 3 60Ω* MAX4108 MAX4109 MAX4308 MAX4309 VEE 4 300Ω * USED TO MATCH A 50Ω SOURCE IMPEDANCE 8 VCC 7 VCC 6 OUT 5 VEE SO DIFFERENCE AMPLIFIER/ADC PREAMPLIFIER ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX4108/MAX4109/MAX4308/MAX4309 _______________General Description The MAX4108/MAX4109/MAX4308/MAX4309 op amps combine ultra-high-speed performance with ultra-lowdistortion operation. The MAX4108 is compensated for unity-gain stability; the MAX4109, MAX4308, and MAX4309 are compensated for minimum closed-loop gains (AVCL) of 2V/V, 5V/V, and 10V/V, respectively. The MAX4108 delivers a 400MHz unity-gain bandwidth with a 1200V/µs slew rate. An ultra-low-distortion design provides an unprecedented spurious-free dynamic range of -93dBc (MAX4108) at 5MHz (VOUT = 2Vp-p, RL = 100Ω), making these amplifiers ideal for high-performance RF signal processing. These high-speed op amps feature a wide output voltage swing and a high-current output-drive capability of 90mA. MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to VEE) ..................................................12V Voltage on Any Pin to Ground or Any Other Pin ..............................(VEE - 0.3V) to (VCC + 0.3V) Short-Circuit Duration (OUT to GND) .........................Continuous Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) ........................471mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10sec) .............................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +5V, VEE = -5V, TA = TMIN to TMAX, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 8 UNITS DC SPECIFICATIONS (RL = ∞) Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Offset Current VOS VOUT = 0V 1 TCVOS VOUT = 0V 13 mV µV/°C IB VOUT = 0V, VIN = -VOS 12 34 µA IOS VOUT = 0V, VIN = -VOS 0.05 2.5 µA Common-Mode Input Resistance RINCM Either input 1.5 MΩ Common-Mode Input Capacitance CINCM Either input 1 pF f = 10kHz 6 nV/√Hz fB = 1MHz to 100MHz 75 µVRMS in f = 10kHz 2 pA/√Hz In fB = 1MHz to 100MHz Input Voltage Noise en Integrated Voltage Noise EnRMS Input Current Noise Integrated Current Noise 25 Common-Mode Input Voltage VCM Common-Mode Rejection CMR VCM = ±2.5V 70 Power-Supply Rejection PSR VS = ±4.5V to ±5.5V Open-Loop Voltage Gain AOL VOUT = ±2.0V, VCM = 0V, RL = 100Ω Quiescent Supply Current IS Output Voltage Swing -2.5 IOUT Short-Circuit Output Current ISC V 100 dB 70 90 dB 70 100 VIN = 0V 20 dB 27 mA RL = ∞ 2.5 to -3.1 2.9 to -3.8 RL = 100Ω 2.5 to -3.1 2.7 to -3.7 65 90 mA 100 mA VOUT Output Current Drive nARMS 2.5 RL = 33Ω, TA = 0°C to +85°C Short to ground V AC SPECIFICATIONS (RL = 100Ω) -3dB Bandwidth 2 BW-3dB VOUT ≤ 0.1VRMS MAX4108 400 MAX4109 225 MAX4308 220 MAX4309 200 _______________________________________________________________________________________ MHz 400MHz, Ultra-Low-Distortion Op Amps (VCC = +5V, VEE = -5V, TA = TMIN to TMAX, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS AC SPECIFICATIONS (RL = 100Ω) (continued) Full-Power Bandwidth 0.1dB Gain Flatness FPBW BW0.1dB VOUT = 2Vp-p MAX4108 300 MAX4109 200 MAX4308 190 MAX4309 130 MAX4108, AVCL = +1 100 MAX4109, AVCL = +2 25 MAX4308, AVCL = +5 100 MAX4309, AVCL = +10 Slew Rate SR -2V ≤ VOUT ≤ 2V Settling Time tS -1V ≤ VOUT ≤ 1V Rise/Fall Times tR, tF Differential Gain 10% to 90% MHz MHz 30 1200 To 0.1% 8 To 0.01% 12 -2V ≤ VOUT ≤ 2V 3 -50mV ≤ VOUT ≤ 50mV 2 V/µs ns ns DG f = 3.58MHz, RL = 150Ω 0.004 % Differential Phase DP f = 3.58MHz, RL = 150Ω 0.008 degrees Input Capacitance CIN 2 pF Output Resistance ROUT 1 Ω f = 10MHz MAX4108, VOUT = 2Vp-p, AVCL = +1 MAX4109, VOUT = 2Vp-p, AVCL = +2 Spurious-Free Dynamic Range SFDR MAX4308, VOUT = 2Vp-p, AVCL = +5 MAX4309, VOUT = 2Vp-p, AVCL = +10 Third-Order Intercept IP3 fC = 10MHz fC = 5MHz, RL = 100Ω -93 fC = 20MHz, RL = 100Ω -81 fC = 5MHz, RL = 100Ω -90 fC = 20MHz, RL = 100Ω -80 fC = 5MHz, RL = 100Ω -83 fC = 20MHz, RL = 100Ω -80 fC = 5MHz, RL = 100Ω -83 fC = 20MHz, RL = 100Ω -80 MAX4108 39 MAX4109 36 MAX4308 46 MAX4309 43 dBc dBm _______________________________________________________________________________________ 3 MAX4108/MAX4109/MAX4308/MAX4309 ELECTRICAL CHARACTERISTICS (continued) __________________________________________Typical Operating Characteristics (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) 4 2 -1 1 -2 0 AVCL = +2 -4 -2 -2 -3 -5 -6 -7 -5 -7 -8 -6 10 100 0.1 1000 AVCL = +5 -4 -4 1 10 100 0.1 1000 1 100 10 1000 FREQUENCY (MHz) FREQUENCY (MHz) FREQUENCY (MHz) MAX4109 LARGE-SIGNAL GAIN vs. FREQUENCY MAX4308 SMALL-SIGNAL GAIN vs. FREQUENCY MAX4309 SMALL-SIGNAL GAIN vs. FREQUENCY NORMALIZED GAIN (dB) -2 -3 -4 -5 4 1 0 -1 -2 -3 2 0 -1 -2 -3 -4 -7 -5 -5 -6 100 10 AVCL = +20 -6 0.1 1000 AVCL = +10 1 -4 1 VOUT ≤ 100mVp-p 3 -6 -8 MAX4308/9 TOCF 2 0 -1 VOUT ≤ 100mVp-p AVCL = +5 3 NORMALIZED GAIN (dB) VOUT = 2Vp-p AVCL = +2 MAX4308/9 TOCE 4 MAX4108/9-D 2 1 1 10 100 1000 0.1 1 10 100 1000 FREQUENCY (MHz) FREQUENCY (MHz) MAX4308/MAX4309 LARGE-SIGNAL GAIN vs. FREQUENCY MAX4108 HARMONIC DISTORTION vs. FREQUENCY MAX4109 HARMONIC DISTORTION vs. FREQUENCY 2 MAX4308 AVCL = +5 1 0 -1 -2 -3 -4 MAX4309 AVCL = +10 -5 -50 VOUT = 2Vp-p AVCL = +1 -60 -70 -80 2ND HARMONIC -90 1 10 FREQUENCY (MHz) 100 1000 VOUT = 2Vp-p AVCL = +2 -30 -50 -70 2ND HARMONIC 3RD HARMONIC 3RD HARMONIC -110 -110 0.1 -10 -90 -100 -6 10 MAX4108/9-i -40 HARMONIC DISTORTION (dBc) VOUT = 2Vp-p 3 HARMONIC DISTORTION (dBc) 4 MAX4308/9 TOCG FREQUENCY (MHz) MAX4108/9-H NORMALIZED GAIN (dB) -1 -3 1 AVCL = +2 -1 -6 0.1 VOUT ≤ 100mVp-p 0 -5 -8 4 2 1 NORMALIZED GAIN (dB) 0 -3 VOUT = 2Vp-p AVCL = +1 3 GAIN (dB) NORMALIZED GAIN (dB) AVCL = +1 MAX4109 SMALL-SIGNAL GAIN vs. FREQUENCY MAX4108/9-B VOUT ≤ 100mVp-p MAX4108/9-A 2 1 MAX4108 LARGE-SIGNAL GAIN vs. FREQUENCY MAX4108/9-C MAX4108 SMALL-SIGNAL GAIN vs. FREQUENCY NORMALIZED GAIN (dB) MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps 0.1 1 10 FREQUENCY (MHz) 100 0.1 1 10 FREQUENCY (MHz) _______________________________________________________________________________________ 100 400MHz, Ultra-Low-Distortion Op Amps MAX4108 HARMONIC DISTORTION vs. LOAD -40 -50 -60 -70 2ND HARMONIC -80 3RD HARMONIC -60 -70 2ND HARMONIC -80 -100 1 10 3RD HARMONIC 1000 100 10 MAX4109 HARMONIC DISTORTION vs. OUTPUT SWING HARMONIC DISTORTION (dBc) -80 -30 3RD HARMONIC AVCL = +1 VOUT = 2Vp-p fO = 20MHz -40 -50 -60 -70 -80 2ND HARMONIC -30 -90 MAX4108/9-O MAX4108 HARMONIC DISTORTION vs. OUTPUT SWING 2ND HARMONIC AVCL = +2 VOUT = 2Vp-p fO = 20MHz -40 -50 -60 -70 -80 2ND HARMONIC -90 3RD HARMONIC 3RD HARMONIC -100 -100 10 100 10 1 INPUT VOLTAGE NOISE vs. FREQUENCY VOLTAGE NOISE (nV√Hz) 40 35 30 25 20 MAX4108/9-TOCR 100 MAX4108/9-Q 45 THIRD-ORDER INTERCEPT (dBm) 2ND HARMONIC -80 10 15 3RD HARMONIC 1 10 -100 0.1 0.1 MAX4109 TWO-TONE THIRD-ORDER INTERCEPT vs. FREQUENCY MAX4108/09 TOCP HARMONIC DISTORTION (dBc) 10 MAX4308/MAX4309 HARMONIC DISTORTION vs. OUTPUT SWING -60 -90 1 OUTPUT SWING (Vp-p) -50 -70 0.1 OUTPUT SWING (Vp-p) VOUT = 2Vp-p fO = 5MHz MAX4308: AVCL = +5 MAX4309: AVCL = +10 -40 1000 -100 RESISTIVE LOAD (Ω) -20 -30 1000 100 MAX4308/MAX4309 HARMONIC DISTORTION vs. LOAD -60 -90 2ND HARMONIC -80 RESISTIVE LOAD (Ω) -50 -70 -70 RESISTIVE LOAD (Ω) VOUT = 2Vp-p fO = 5MHz MAX4308: AVCL = +5 MAX4309: AVCL = +10 -40 -60 FREQUENCY (MHz) -20 -30 -50 -100 10 100 MAX4108/09 TOCM 0.1 AVCL = +2 VOUT = 2Vp-p fO = 20MHz -40 -90 3RD HARMONIC MAX4108/9-L -30 MAX4108/9-K -50 -90 -100 HARMONIC DISTORTION (dBc) -40 MAX4108/9-N -90 AVCL = +1 VOUT = 2Vp-p fO = 20MHz HARMONIC DISTORTION (dBc) HARMONIC DISTORTION (dBc) -30 -30 MAX4109 HARMONIC DISTORTION vs. LOAD HARMONIC DISTORTION (dBc) VOUT = 2Vp-p MAX4308: AVCL = +5 MAX4309: AVCL = +10 HARMONIC DISTORTION (dBc) -20 MAX4108/09 TOCJ MAX4308/MAX4309 HARMONIC DISTORTION vs.FREQUENCY 1 RESISTIVE LOAD (Ω) 10 1 10 FREQUENCY (MHz) 100 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) _______________________________________________________________________________________ 5 MAX4108/MAX4109/MAX4308/MAX4309 ____________________________Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) ____________________________Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) 0 0 100 100 DIFF PHASE (deg) DIFF PHASE (deg) IRE 0.006 AVCL = +1V 0.004 0.002 0.000 -0.002 0 100 0.002 AVCL = +2V 0.000 -0.002 -0.004 -0.006 0 100 100 MAX4308 DIFFERENTIAL GAIN AND PHASE (RL = 150Ω) MAX4309 DIFFERENTIAL GAIN AND PHASE (RL = 150Ω) AVCL = +2V 0 0.002 AVCL = +5V 0.000 -0.002 -0.004 -0.006 100 0 IRE 0.004 AVCL = +10V 0.002 0.000 -0.002 -0.004 100 0 100 0.004 AVCL = +5V 0.002 0.000 -0.002 -0.004 100 0 IRE DIFF PHASE (deg) DIFF PHASE (deg) IRE 0.006 AVCL = +2V 0.004 0.002 0.000 -0.002 0 IRE 0.002 AVCL = +10V 0.000 -0.002 -0.004 -0.006 -0.008 -0.010 100 0 100 IRE MAX4108 SMALL-SIGNAL PULSE RESPONSE (AVCL = +1) IRE MAX4108 SMALL-SIGNAL PULSE RESPONSE (AVCL = +2) MAX4108 LARGE-SIGNAL PULSE RESPONSE (AVCL = +1) MAX4108/9-AA MAX4108/9-Z MAX4108/9-Y GND IN IN GND VOLTAGE (10mV/div) VOLTAGE (500mV/div) GND IN MAX4108/9-X MAX4109 DIFFERENTIAL GAIN AND PHASE (RL = 75Ω) DIFF GAIN (%) IRE MAX4108/9-W IRE MAX4108/9-V DIFF GAIN (%) 0 100 IRE DIFF GAIN (%) DIFF PHASE (deg) 0.004 AVCL = +1V 0.002 0.000 -0.002 -0.004 0 DIFF PHASE (deg) 0.004 AVCL = +2V 0.002 0.000 -0.002 -0.004 IRE IRE 0.006 0.004 0.002 0.000 -0.002 MAX4108/9-U 0.008 AVCL = +1V 0.006 0.004 0.002 0.000 -0.002 DIFF GAIN (%) DIFF GAIN (%) MAX4108/9-S DIFF GAIN (%) 0.004 AVCL = +1V 0.002 0.000 -0.002 -0.004 MAX4109 DIFFERENTIAL GAIN AND PHASE (RL = 150Ω) MAX4108/9-T MAX4108 DIFFERENTIAL GAIN AND PHASE (RL = 75Ω) MAX4108 DIFFERENTIAL GAIN AND PHASE (RL = 150Ω) VOLTAGE (20mV/div) MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps GND OUT GND TIME (10ns/div) 6 OUT OUT TIME (10ns/div) GND TIME (10ns/div) _______________________________________________________________________________________ 400MHz, Ultra-Low-Distortion Op Amps MAX4108 LARGE-SIGNAL PULSE RESPONSE (AVCL = +2) MAX4108/9-DD MAX4108/9-CC MAX4108/9-BB VOLTAGE (10mV/div) VOLTAGE (500mV/div) GND IN GND OUT GND IN VOLTAGE (500mV/div) GND IN MAX4109 LARGE-SIGNAL PULSE RESPONSE (AVCL = +2) MAX4109 SMALL-SIGNAL PULSE RESPONSE (AVCL = +2) GND GND OUT OUT TIME (10ns/div) TIME (10ns/div) TIME (10ns/div) MAX4308 SMALL-SIGNAL PULSE RESPONSE (AVCL = +5) MAX4308 LARGE-SIGNAL PULSE RESPONSE (AVCL = +5) MAX4309 SMALL-SIGNAL PULSE RESPONSE (AVCL = +10) MAX4108/9EE MAX4108/9FF VOLTAGE (1V/div) VOLTAGE (100mV/div) GND IN OUT GND IN GND VOLTAGE (25mV/div) GND IN MAX4108/9GG OUT GND GND OUT TIME (10ns/div) TIME (10ns/div) TIME (10ns/div) MAX4309 SMALL-SIGNAL PULSE RESPONSE (AVCL = +20) MAX4309 LARGE-SIGNAL PULSE RESPONSE (AVCL = +10) MAX4309 LARGE-SIGNAL PULSE RESPONSE (AVCL = +20) OUT GND IN GND IN GND GND GND GND OUT TIME (10ns/div) MAX4108/9JJ VOLTAGE (500mV/div) VOLTAGE (25mV/div) IN MAX4108/9ii VOLTAGE (500mV/div) MAX4108/9HH OUT TIME (10ns/div) TIME (10ns/div) _______________________________________________________________________________________ 7 MAX4108/MAX4109/MAX4308/MAX4309 ____________________________Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) ____________________________Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, RL = 100Ω, TA = +25°C, unless otherwise noted.) 70 60 MAX4109/ MAX4309 50 40 30 20 10 80 70 MAX4109/ MAX4309 60 50 40 30 10 1 10 100 1000 MAX4108/9-MM 10 1 0.1 0.1 1 10 100 1000 0.1 1 10 100 FREQUENCY (MHz) FREQUENCY (MHz) FREQUENCY (MHz) OUTPUT SWING vs. LOAD RESISTANCE INPUT OFFSET VOLTAGE vs. TEMPERATURE INPUT BIAS CURRENT vs. TEMPERATURE 3.5 1.8 3.0 25 23 21 1.6 1000 MAX4108/9-PP 2.0 MAX4108/9-NN 4.0 MAX4108/9-OO 0.2 2.0 1.5 CURRENT (µA) VOLTAGE (mV) 19 2.5 1.4 1.2 1.0 1.0 0.8 0.5 0.6 0 50 70 90 110 130 13 9 7 150 5 -75 -50 -25 0 25 50 75 -75 100 125 -50 -25 0 25 50 75 LOAD RESISTANCE (Ω) TEMPERATURE (°C) TEMPERATURE (°C) INPUT OFFSET CURRENT vs. TEMPERATURE POWER-SUPPLY CURRENT vs. TEMPERATURE OUTPUT SWING vs. TEMPERATURE 30 MAX4108/9-QQ 0.100 POSITIVE SUPPLY CURRENT 20 0.060 10 0 -10 0.040 NEGATIVE SUPPLY CURRENT -20 -50 -25 0 25 50 TEMPERATURE (°C) 75 100 125 4.0 RL = ∞ 3.0 100 125 RL = 100Ω 2.0 1.0 0.0 -1.0 -2.0 -3.0 RL = 100Ω -4.0 RL = ∞ -5.0 -30 0.020 5.0 OUTPUT SWING (V) CURRENT (mA) 0.080 -75 15 MAX4108/9-SS 30 17 11 0.4 10 8 100 20 0 OUTPUT SWING (VPEAK) MAX4108/MAX4308 90 1000 OUTPUT IMPEDANCE (Ω) MAX4108/MAX4308 80 110 100 CLOSED-LOOP OUTPUT IMPEDANCE vs. FREQUENCY MAX4108/9-RR POWER-SUPPLY REJECTION (dB) 90 COMMON-MODE REJECTION (dB) MAX4108/9-KK 100 COMMON-MODE REJECTION vs. FREQUENCY MAX4108/9-LL POWER-SUPPLY REJECTION vs. FREQUENCY CURRENT (µA) MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps -75 -50 -25 0 25 50 TEMPERATURE (°C) 75 100 125 -75 -50 -25 0 25 50 TEMPERATURE (°C) _______________________________________________________________________________________ 75 100 125 400MHz, Ultra-Low-Distortion Op Amps PIN NAME FUNCTION 1 N.C. No Connection. Not internally connected. 2 IN- Inverting Input 3 IN+ Noninverting Input 4, 5 VEE Negative Power Supply, connect to -5VDC. 6 OUT Amplifier Output 7, 8 VCC Positive Power Supply, connect to +5VDC. _______________Detailed Description Choosing Resistor Values Unity-Gain Configuration The MAX4108 is internally compensated for unity gain. When configured for unity gain, the device requires a small resistor in series with the feedback path. This resistor improves the AC response by reducing the Q of the tank circuit, which is formed by parasitic feedback inductance and capacitance. The MAX4108/MAX4109/MAX4308/MAX4309 are ultralow-distortion, high-bandwidth op amps. The output distortion will be degraded as the total load resistance seen by the amplifier decreases. To minimize distortion products, keep the input and gain-setting resistors relatively large. A 500Ω feedback resistor combined with an appropriate input resistor to set the gain will provide excellent AC performance without significantly increasing distortion. RF 25 MAX4108/9-1B RG Inverting and Noninverting Configurations The values of the gain-setting feedback and input resistors are important design considerations. Large resistor values will increase voltage noise, and will interact with the amplifier’s input and PC board capacitance to generate undesirable poles and zeros, which can decrease bandwidth or cause oscillations. For example, a noninverting gain of +2, using 1kΩ resistors combined with 2pF of input capacitance and 0.5pF of board capacitance, will cause a feedback pole at 128MHz. If this pole is within the anticipated amplifier bandwidth, it will jeopardize stability. Reducing these 1kΩ resistors to 100Ω will extend the pole frequency to 1.28GHz, but could limit output swing by adding 200Ω in parallel with the amplifier’s load. Clearly, the selection of resistor values must be tailored to the specific application. RS VIN CL RL ISOLATION RESISTANCE (Ω) MAX4108 20 MAX4308 15 MAX4109/MAX4309 10 5 PART MAX4108 MAX4109 MAX4308 MAX4309 RF (Ω) 24 500 500 500 RG (Ω) ∞ 500 125 56 GAIN (V/V) 1 2 5 10 Figure 1a. Using an Isolation Resistor for High Capacitive Loads 0 10 40 70 100 130 160 190 220 CAPACITANCE (pF) Figure 1b. Optimal Isolation Resistor (RS) vs. Capacitive Load _______________________________________________________________________________________ 9 MAX4108/MAX4109/MAX4308/MAX4309 _____________________Pin Description RS = 0Ω AVCL = +1 CL = 15pF 8 6 CL = 10pF 4 2 0 -2 20 CL = 5pF RS = 0Ω AVCL = +2 18 CLOSED-LOOP GAIN (dB) 16 14 12 CL = 10pF 10 8 6 -4 4 -6 2 -8 CL = 5pF 0 0.1 1 10 100 0.1 1000 1 FREQUENCY (MHz) RS = 0Ω AVCL = +5 4 3 2 NORMALIZED GAIN (dB) 2 CL = 15pF 1 0 -1 -2 -3 CL = 10pF RS = 0Ω AVCL = +10 1000 CL = 15pF 1 0 -1 -2 CL = 5pF -3 CL = 10pF -4 -4 -5 100 Figure 2b. MAX4109 Response vs. Capacitive Load—No Resistive (RS) Isolation (circuit shown in Figure 1a) MAX4108/9-2C 4 3 10 FREQUENCY (MHz) Figure 2a. MAX4108 Response vs. Capacitive Load—No Resistive (RS) Isolation (circuit shown in Figure 1a) -5 CL = 5pF -6 -6 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 2c. MAX4308 Response vs. Capacitive Load—No Resistive (RS) Isolation (circuit shown in Figure 1a) 10 CL = 15pF MAX4108/9-2D CLOSED-LOOP GAIN (dB) 10 MAX4108/9-2A 12 eliminates this problem, and Figure 1b is a graph of the optimal isolation resistor (R S ) vs. capacitive load. Figures 2a–2d show how a capacitive load causes excessive peaking of the amplifier’s bandwidth if the capacitive load is not isolated (RS) from the amplifier. A small isolation resistor (usually 15Ω to 22Ω) placed MAX4108/9-2B Driving Capacitive Loads The MAX4108/MAX4109/MAX4308/MAX4309 are optimized for AC performance. They are not designed to drive highly reactive loads. Reactive loads will decrease phase margin and may produce excessive ringing and oscillation. Figure 1a shows a circuit that NORMALIZED GAIN (dB) MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 2d. MAX4309 Response vs. Capacitive Load—No Resistive (RS) Isolation (circuit shown in Figure 1a) ______________________________________________________________________________________ 400MHz, Ultra-Low-Distortion Op Amps Input buffer amplifiers can be a source of significant errors in high-speed ADC applications. The input buffer is usually required to rapidly charge and discharge the ADC’s input, which is often capacitive (see the section Driving Capacitive Loads). In addition, a high-speed ADC’s input impedance often changes very rapidly during the conversion cycle, requiring an amplifier with very low output impedance at high frequencies to maintain measurement accuracy. The combination of high speed, fast slew rate, low noise, and a low and stable distortion over load makes the MAX4108/MAX4109/ MAX4308/MAX4309 ideally suited for use as buffer amplifiers in high-speed ADC applications. CL = 10pF AVCL = +1 8 RS = 22Ω 2 0 RS = 30Ω -2 -4 MAX4108/9-3B 6 5 4 RS = 15Ω 1 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 3b. MAX4308 Response vs. Capacitive Load with Resistive (RS) Isolation (circuit shown in Figure 1a) 4 CL = 10pF AV = +5 3 2 RS = 10Ω 6 4 RS = 8.2Ω 7 2 NORMALIZED GAIN (dB) CLOSED-LOOP GAIN (dB) 10 8 3 MAX4108/9-3A 12 9 MAX4108/9-3C ADC Input Buffers CL = 10pF AVCL = +2 10 CLOSED-LOOP GAIN (dB) Coaxial cable and other transmission lines are easily driven when terminated at both ends with their characteristic impedance. When driving back-terminated transmission lines, the capacitance of the transmission line is essentially eliminated. 11 MAX4108/MAX4109/MAX4308/MAX4309 before the reactive load prevents ringing and oscillation. At higher capacitive loads, AC performance will be controlled by the interaction of the load capacitance and isolation resistor. Figures 3a–3c show the effect of an isolation resistor on the MAX4108/MAX4109/ MAX4308/MAX4309 closed-loop response. 1 0 -1 RS = 8.2Ω RS = 15Ω RS = 47Ω -2 -3 -4 -6 -5 -8 -6 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 3a. MAX4108 Response vs. Capacitive Load with Resistive (RS) Isolation (circuit shown in Figure 1a) 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 3c. MAX4108/MAX4309 Response vs. Capacitive Load with Resistive (RS) Isolation (circuit shown in Figure 1a) ______________________________________________________________________________________ 11 ___________________Chip Information TRANSISTOR COUNT: 57 SUBSTRATE CONNECTED TO VEE ________________________________________________________Package Information SOICN.EPS MAX4108/MAX4109/MAX4308/MAX4309 400MHz, Ultra-Low-Distortion Op Amps Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 12 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.