PART MAX477EUA MAX477ESA MAX477 V OUT OUT. Maxim Integrated Products 1

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1 9-67; Rev 3; /99 EVALUATION KIT MANUAL FOLLOWS DATA SHEET 3MHz High-Speed Op Amp General Description The is a ±5V wide-bandwidth, fast-settling, unity-gain-stable op amp featuring low noise, low differential gain and phase errors, high slew rate, high precision, and high output current. The s architecture uses a standard voltage-feedback topology that can be configured into any desired gain setting, as with other general-purpose op amps. Unlike high-speed amplifiers using current-mode feedback architectures, the has a unique input stage that combines the benefits of the voltage-feedback design (flexibility in choice of feedback resistor, two high-impedance inputs) with those of the currentfeedback design (high slew rate and full-power bandwidth). It also has the precision of voltage-feedback amplifiers, characterized by low input-offset voltage and bias current, low noise, and high common-mode and power-supply rejection. The is ideally suited for driving 5Ω or loads and is available in -pin DIP, SO, space-saving µmax, and 5-pin SOT3 packages. Applications Features High Speed 3MHz -3dB Bandwidth (AV = +) MHz Full-Power Bandwidth (AV = +,V O = Vp-p) V/µs Slew Rate 3MHz.dB Gain Flatness Drives pf Capacitive Loads Without Oscillation Low Differential Phase/Gain Error:. /.% ma Quiescent Current Low Input-Referred Voltage Noise: 5nV/ Hz Low Input-Referred Current Noise: pa/ Hz Low Input Offset Voltage:.5mV V ESD Protection Voltage-Feedback Topology for Simple Design Configurations Short-Circuit Protected Available in Space-Saving SOT3 Package Ordering Information Broadcast and High-Definition TV Systems Video Switching and Routing Communications Medical Imaging Precision DAC/ADC Buffer PART EPA ESA EUA TEMP. RANGE - C to +5 C - C to +5 C - C to +5 C P- PACKAGE Plastic DIP SO µmax EUK-T - C to +5 C 5 SOT3-5 MJA -55 C to +5 C CERDIP TOP MARK ABYW Typical Operating Circuit Pin Configuration TOP VIEW V V 5 V CC N.C. N.C. - 7 V CC 5Ω 5Ω V EE V EE 5 N.C. VIDEO/RF CABLE DRIVER SOT3-5 DIP/SO/µMAX Maxim Integrated Products For price, delivery, and to place orders, please contact Maxim Distribution at , or visit Maxim s website at

2 3MHz High-Speed Op Amp ABSOLUTE MAXIMUM RATGS Supply Voltage (V CC to V EE )...V Differential Input Voltage...(V CC +.3V) to (V EE -.3V) Common-Mode Input Voltage...(V CC +.3V) to (V EE -.3V) Output Short-Circuit Duration to...continuous Continuous Power Dissipation (T A = +7 C) Plastic DIP (derate 9.9mW/ C above +7 C)...77mW SO (derate 5.mW/ C above +7 C)...7mW µmax (derate.mw/ C above +7 C)...33mW CERDIP (derate.mw/ C above +7 C)...6mW SOT3 (derate 7.mW/ C above +7 C)...57mW Operating Temperature Ranges E_A...- C to +5 C EUK...- C to +5 C MJA C to +5 C Storage Temperature Range C to +6 C Lead Temperature (soldering, s)...+3 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. DC ELECTRICAL CHARACTERISTICS (V CC = +5V, V EE = -5V, V =, R L =, T A = T M to T MAX, unless otherwise noted. Typical values are at T A = +5 C.) (Note ) PARAMETER Input Offset Voltage Input Offset-Voltage Drift Input Bias Current I B T A = +5 C 3 T A = T M to T MAX 5. Input Offset Current I OS T A = +5 C.. T A = T M to T MAX. Differential-Mode Input Resistance Either input Common-Mode Input Voltage T A = +5 C ±3. ±3.5 V CM Range T A = T M to T MAX ±.5 T A = +5 C V CM = ±3V 7 9 Common-Mode Rejection Ratio CMRR T A = T M to T MAX V CM = ±.5V 6 Power-Supply Rejection Ratio PSRR V S = ±.5V to ±5.5V 7 5 Open-Loop Voltage Gain V = ±.V, E_A/77MJA Open-Loop Voltage Gain A VOL V CM = V, R L = 5Ω EUK 5 65 T A = +5 C R L = ±3.5 ±3.9 Output Voltage Swing V R L = Ω ±3. T A = T M to T MAX R L = 5Ω ±.5 Minimum Output Current I T A = - C to +5 C 7 Short-Circuit Output Current Open-Loop Output Resistance SYMBOL V OS TCV OS R (DM) I SC R CONDITIONS M TYP MAX ESA/EPA/EUA/MJA.5. T A = +5 C EUK.5. ESA/EPA/EUA/MJA T A = T M to 3. EUK T MAX 5. Short to ground V =, f = DC T A = +5 C Quiescent Supply Current I SY E, T A = T M to T MAX MJA, T A = T M to T MAX 5. UNITS mv µv/ C µa µa MΩ V db db db V ma ma Ω ma ma

3 3MHz High-Speed Op Amp AC ELECTRICAL CHARACTERISTICS (V CC = +5V, V EE = -5V, R L = Ω, A VCL = +, T A = +5 C, unless otherwise noted.) PARAMETER Small Signal, -3dB Bandwidth Small Signal, ±.db Gain Flatness Full-Power Bandwidth Slew Rate Settling Time Rise Time, Fall Time Input Voltage Noise Density SYMBOL BW -3dB CONDITIONS M TYP MAX 3 UNITS BW.dB V.Vp-p 3 MHz FPBW SR t S t R, t F e n V.Vp-p V = Vp-p V = ±Vp-p V = V step V = V step f = MHz to.% to.% 5 MHz MHz V/µs ns ns nv/ Hz Input Current Noise Density i n f = MHz, either input pa/ Hz Differential Gain (Note ) DG f = 3.5MHz. % Differential Phase (Note ) DP f = 3.5MHz. degrees Differential-Mode Input Capacitance C (DM) Either input pf Output Impedance Z f = MHz.5 Ω Total Harmonic Distortion THD f c = MHz, V = Vp-p -5 db Spurious-Free Dynamic Range SFDR f = 5MHz, V = Vp-p -7 dbc Third-Order Intercept IP3 f = MHz, V = Vp-p 36 dbm Note : Specifications for the EUK (SOT3 package) are % tested at T A = +5 C, and guaranteed by design over temperature. Note : Tested with a 3.5MHz video test signal with an amplitude of IRE superimposed on a linear ramp ( to IRE). An IRE is a unit of video-signal amplitude developed by the Institute of Radio Engineers. IRE = V. Typical Operating Characteristics (V CC = +5V, V EE = -5V, R L = Ω, C L = pf, T A = +5 C, unless otherwise noted.) SMALL-SIGNAL GA vs. FREQUENCY (A VCL = +V/V) - 7 SMALL-SIGNAL GA vs. FREQUENCY (A VCL = +V/V) - SMALL-SIGNAL GA vs. FREQUENCY (A VCL = +V/V) GA (db) GA (db) 3 GA (db) M M M G - M M M G k M M M 3

4 3MHz High-Speed Op Amp Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, C L = pf, T A = +5 C, unless otherwise noted.) GA (db) GA FLATNESS vs. FREQUENCY (A VCL = +V/V) - GA (db) LARGE-SIGNAL GA vs. FREQUENCY (A VCL = +V/V) -5 (mv/div) SMALL-SIGNAL PULSE RESPONSE (A VCL = +V/V) -.6 M M M G -6 M M M G TIME (ns/div) SMALL-SIGNAL PULSE RESPONSE (A VCL = +V/V) SMALL-SIGNAL PULSE RESPONSE (A VCL = +V/V) LARGE-SIGNAL PULSE RESPONSE (A VCL = +V/V) (5mV/div) (5mV/div) (V/div) (mv/div) (5mV/div) TIME (ns/div) TIME (5ns/div) TIME (ns/div) LARGE-SIGNAL PULSE RESPONSE (A VCL = +V/V) LARGE-SIGNAL PULSE RESPONSE (A VCL = +V/V) SMALL-SIGNAL PULSE RESPONSE (A VCL = +V/V, C L = 5pF) (V/div) (V/div) (mv/ div) (V/div) (mv/div) TIME (ns/div) TIME (5ns/div) TIME (ns/div)

5 3MHz High-Speed Op Amp Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, C L = pf, T A = +5 C, unless otherwise noted.) SMALL-SIGNAL PULSE RESPONSE (A VCL = +V/V, C L = pf) LARGE-SIGNAL PULSE RESPONSE (A VCL = +V/V, C L = 5pF) LARGE-SIGNAL PULSE RESPONSE (A VCL = +V/V, C L = pf) (mv/div) (V/div) (V/div) TIME (ns/div) TIME (ns/div) TIME (ns/div) PUT OFFSET (µv) PUT OFFSET (V OS ) vs. TEMPERATURE V CM = V -7 QUIESCENT SUPPLY CURRENT (ma) 6 QUIESCENT SUPPLY CURRENT (I SY ) vs. TEMPERATURE - PUT BIAS CURRENT (µa) PUT BIAS CURRENT (I B ) vs. TEMPERATURE V CM = V TEMPERATURE ( C) TEMPERATURE ( C) TEMPERATURE ( C). PUT SWG vs. TEMPERATURE R L = -.. PUT COMMON-MODE RANGE (V CM ) vs. TEMPERATURE - PUT SWG (±V) R L = W R L = 5W COMMON-MODE RANGE (±V) TEMPERATURE ( C) TEMPERATURE ( C) 5

6 3MHz High-Speed Op Amp Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, C L = pf, T A = +5 C, unless otherwise noted.) POWER-SUPPLY REJECTJION (db) POWER-SUPPLY REJECTION vs. FREQUENCY 3k k M M M - PUT IMPEDANCE (Ω) k PUT IMPEDANCE vs. FREQUENCY. k M M M 5M -3 - HARMONIC DISTORTION vs. FREQUENCY - OPEN-LOOP GA AND PHASE vs. FREQUENCY DISTORTION (db) TOTAL HARMONIC DISTORTION SECOND HARMONIC THIRD HARMONIC OPEN-LOOP GA (db) PHASE GA - PHASE (DEGREES) k k k M M M - 5M M 5M DIFF PHASE (DEGREES) DIFF GA (%) DIFFERENTIAL GA AND PHASE (A VCL = +, R L = 5Ω) IRE IRE -5 DIFF PHASE (DEGREES) DIFF GA (%) DIFFERENTIAL GA AND PHASE (A VCL = +, R L = 5Ω) IRE IRE -6 6

7 3MHz High-Speed Op Amp Pin Description P SO/µMAX/DIP, 5, SOT3 3 5 NAME N.C. No Connect. Not internally connected. Inverting Input Noninverting Input Negative Power Supply Amplifier Output Positive Power Supply Detailed Description The allows the flexibility and ease of a classic voltage-feedback architecture while maintaining the high-speed benefits of current-mode feedback (CMF) amplifiers. Although the is a voltage-feedback op amp, its internal architecture provides an V/µs slew rate and a low ma supply current. CMF amplifiers offer high slew rates while maintaining low supply current, but use the feedback and load resistors as part of the amplifier s frequency compensation network. In addition, they have only one input with high impedance. The has speed and power specifications like those of current-feedback amplifiers, but has high input impedance at both input terminals. Like other voltagefeedback op amps, its frequency compensation is independent of the feedback and load resistors, and it exhibits a constant gain-bandwidth product. However, unlike standard voltage-feedback amplifiers, its largesignal slew rate is not limited by an internal current source, so the exhibits a very high full-power bandwidth. Output Short-Circuit Protection Under short-circuit conditions, the output current is typically limited to 5mA. This is low enough that a short to ground of any duration will not cause permanent damage to the chip. However, a short to either supply will significantly increase the power dissipation and may cause permanent damage. The high outputcurrent capability is an advantage in systems that transmit a signal to several loads. See High-Performance Video Distribution Amplifier in the Applications Information section. - + V EE V CC FUNCTION Applications Information Grounding, Bypassing, and PC Board Layout To obtain the s full 3MHz bandwidth, microstrip and stripline techniques are recommended in most cases. To ensure the PC board does not degrade the amplifier s performance, design the board for a frequency greater than GHz. Even with very short traces, use these techniques at critical points, such as inputs and outputs. Whether you use a constant-impedance board or not, observe the following guidelines when designing the board: Do not use wire-wrap boards. They are too inductive. Do not use IC sockets. They increase parasitic capacitance and inductance. In general, surface-mount components have shorter leads and lower parasitic reactance, giving better high-frequency performance than through-hole components. The PC board should have at least two layers, with one side a signal layer and the other a ground plane. Keep signal lines as short and straight as possible. Do not make 9 turns; round all corners. The ground plane should be as free from voids as possible. Setting Gain The can be configured as an inverting or noninverting gain block in the same manner as any other voltage-feedback op amp. The gain is determined by the ratio of two resistors and does not affect amplifier frequency compensation. This is unlike CMF op amps, which have a limited range of feedback resistors, typically one resistor value for each gain and load setting. This is because the -3dB bandwidth of a CMF op amp is set by the feedback and load resistors. Figure a shows the inverting gain configuration and its gain V R G V = -(R F /R G ) V R F V Figure a. Inverting Gain Configuration 7

8 3MHz High-Speed Op Amp R G V V = [ + (R F /R G )] V Figure b. Noninverting Gain Configuration V equation, while Figure b shows the noninverting gain configuration. Choosing Resistor Values The feedback and input resistor values are not critical in the inverting or noninverting gain configurations (as with current-feedback amplifiers). However, be sure to select resistors that are small and noninductive. Surface-mount resistors are best for high-frequency circuits. Their material is similar to that of metal-film resistors, but to minimize inductance, it is deposited in a flat, linear manner using a thick film. Their small size and lack of leads also minimize parasitic inductance and capacitance. The s input capacitance is approximately pf. In either the inverting or noninverting configuration, excess phase resulting from the pole frequency formed by R f R g and C can degrade amplifier phase margin and cause oscillations (Figure ). Table shows the recommended resistor combinations and measured bandwidth for several gain values. DC and Noise Errors The standard voltage-feedback topology of the allows DC error and noise calculations to be done in the usual way. The following analysis shows V R G C R F R F R L V Table. Resistor and Bandwidth Values for Various Closed-Loop Gain Configurations GA (V/V) that the s voltage-feedback architecture provides a precision amplifier with significantly lower DC errors and lower noise compared to CMF amplifiers. ) In Figure 3, total output offset error is given by: V = + R f R g V I R I R R I R R R OS B S B f g OS S f g For the special case in which R S is arranged to be equal to Rf Rg, the I B terms cancel out. Note also, for I OS (R S + (Rf Rg) << V OS, the I OS term also drops out of the equation for total DC error. In practice, high-speed configurations for the necessitate the use of low-value resistors for R S, R f, and Rg. In this case, the V OS term is the dominant DC error source. ) The s total input-referred noise in a closedloop feedback configuration can be calculated by: where e n i n = input-referred noise voltage of the (5nV Hz) = input-referred noise current of the (pa Hz) R EQ = total equivalent source resistance at the two inputs, i.e., R EQ = R S + R f R g e R R g (Ω) R f (Ω) e e e i R T n R n EQ = + +( ) -3dB BANDWIDTH (MHz) + Open Short = resistor noise voltage due to REQ, i.e., Figure. Effect of High-Feedback Resistor Values and Parasitic Capacitance on Bandwidth e R = KT REQ

9 3MHz High-Speed Op Amp As an example, consider R S =, Rf = R g = 5Ω. Then: R = EQ +( 5Ω 5Ω)= 35Ω e = KT x 35 =. 3nV / Hz at + 5 C R e = nv nv pa x nv Hz T ( 5 ) + (. 3 ) + ( 35) = 5. 5 V R g R S I B- I B+ R f V 3) The s output-referred noise is simply total input-referred noise, e T, multiplied by the gain factor: e = e + R f T R g In the above example, with e T = 5.5nV Hz, and assuming a signal bandwidth of 3MHz (7MHz noise bandwidth), total output noise in this bandwidth is: e = 5.5nV x 5 + x 7MHz = 39µ V 5 RMS Note that for both DC and noise calculations, errors are dominated by offset voltage (V OS ) and input noise voltage (e n ). For a current-mode feedback amplifier with offset and noise errors significantly higher, the calculations are very different. Driving Capacitive Loads The provides maximum AC performance with no output load capacitance. This is the case when the is driving a correctly terminated transmission line (i.e., a back-terminated cable). However, the is capable of driving capacitive loads up to pf without oscillations, but with reduced AC performance. Driving large capacitive loads increases the chance of oscillations in most amplifier circuits. This is especially true for circuits with high loop gain, such as voltage followers. The amplifier s output resistance and the load capacitor combine to add a pole and excess phase to the loop response. If the frequency of this pole is low enough and phase margin is degraded sufficiently, oscillations may occur. A second problem when driving capacitive loads results from the amplifier s output impedance, which looks inductive at high frequency. This inductance forms an L-C resonant circuit with the capacitive load, which causes peaking in the frequency response and degrades the amplifier s gain margin. Figure 3. Output Offset Voltage GA (db) C L = pf C L = pf C L = pf M M M G C L = pf Figure. Effect of C LOAD on Frequency Response (A VCL = +V/V) The drives capacitive loads up to pf without oscillation. However, some peaking (in the frequency domain) or ringing (in the time domain) may occur. This is shown in Figure and in the Small and Large- Signal Pulse Response graphs in the Typical Operating Characteristics. To drive larger-capacitance loads or to reduce ringing, add an isolation resistor between the amplifier s output and the load, as shown in Figure 5. The value of R ISO depends on the circuit s gain and the capacitive load. Figure 6 shows the Bode plots that result when a Ω isolation resistor is used with a voltage follower driving a range of capacitive loads. At the higher capacitor values, the bandwidth is dominated by the RC network, formed by R ISO and C L ; the bandwidth of the amplifier itself is much higher. Note that adding an isolation resistor degrades gain accuracy. The load and isolation resistor form a divider that decreases the voltage delivered to the load. 9

10 3MHz High-Speed Op Amp Flash ADC Preamp The s high output-drive capability and ability to drive capacitive loads make it well suited for buffering the low-impedance input of a high-speed flash ADC. With its low output impedance, the can drive the inputs of the ADC while maintaining accuracy. Figure 7 shows a preamp for digitizing video, using the 5Msps MAX and the 5Msps MAX flash ADCs. Both of these ADCs have a 5Ω input resistance and a.ghz input bandwidth. V R ISO Figure 5. Capacitive-Load Driving Circuit C L = pf C L C L = pf R L V High-Performance Video Distribution Amplifier In a gain of + configuration, the makes an excellent driver for back-terminated video coaxial cables (Figure ). The high output-current drive allows the attachment of up to six ±Vp-p, 5Ω loads to the at +5 C. With the output limited to ±Vp-p, the number of loads may double. The MAX7 is a similar amplifier configured for a gain of + without the need for external gain-setting resistors. For multiple gain-of- video line drivers in a single package, refer to the MAX96/MAX97 data sheet. Wide-Bandwidth Bessel Filter Two high-impedance inputs allow the to be used in all standard active filter topologies. The filter design is straightforward because the component values can be chosen independently of op amp bias. Figure 9 shows a wide-bandwidth, second-order Bessel filter using a multiple feedback topology. The component values are chosen for a gain of +, a -3dB bandwidth of MHz, and a ns delay. Figure a shows a square-wave pulse response, and Figure b shows the filter s frequency response and delay. Notice the flat delay in the passband, which is characteristic of the Bessel filter. - GA (db) - -3 R ISO = W 5Ω 5Ω - C L = pf -5-6 C L = 7pF M M M G VIDEO Figure 6. Effect of C LOAD on Frequency Response with Isolation Resistor 5Ω 5Ω N VIDEO FLASH ADC (MAX/MAX) Figure 7. Preamp for Video Digitizer Figure. High-Performance Video Distribution Amplifier

11 3MHz High-Speed Op Amp V 3Ω 6Ω Ω pf Chip Information TRANSISTOR COUNT: 75 SUBSTRATE CONNECTED TO V EE pf V Figure 9. MHz Bessel Filter (mv/div).v (V) (mv/div) -.V TIME (5ns/div) Figure a. 5MHz Square Wave Input GA (db) DELAY - - GA M M M FREQUENCY (MHz) DELAY (ns) Figure b. Gain and Delay vs. Frequency

12 3MHz High-Speed Op Amp Package Information SOT5L.EPS LUMAXD.EPS