19-2359; Rev 0; 3/02 MAX4450 Evaluation Kit Simplified Circuit Features ♦ 3-Pole, Active Lowpass, Sallen-Key Video Filter ♦ 5.25MHz -3dB Bandwidth ♦ >20dB Attenuation at 13.5MHz ♦ >40dB Attenuation at 27MHz ♦ 18dB/Octave Attenuation Rate ♦ Low-Cost Circuit Design ♦ Video-Filter Solution for NTCS and PAL Applications ♦ ±2.25V to ±5.5V Dual-Supply Voltage or +4.5V to +11V Single-Supply Voltage ♦ Surface-Mount Construction ♦ Fully Assembled and Tested Ordering Information C2 R1 INPUT R2 PART MAX4450EVKIT VCC R3 TEMP RANGE 0°C to +70°C IC PACKAGE 5 SOT23 R6 R11 C3 C1 MAX4450 OUTPUT VEE R5 R4 Component List DESIGNATION QTY C1 C2 1 1 DESCRIPTION 330pF ±2%, 50V COG ceramic capacitor (0603) Murata GRM1885C1H331GA01D 100pF ±2%, 50V COG ceramic capacitor (0603) Murata GRM1885C1H101GA01D DESIGNATION QTY DESCRIPTION R1, R6, R11 3 75Ω ±1% resistors (0603) R2 1 221Ω ±1% resistor (0603) R3 1 332Ω ±1% resistor (0603) 604Ω ±1% resistors (0603) R4, R5 2 R7–R10 0 Not installed (0603) U1 1 MAX4450EUK, 5-pin SOT23 INPUT, OUTPUT 2 75Ω BNC connectors, A/D Electronics 580-072-10 C3 1 82pF ±2%, 50V COG ceramic capacitor (0603) Murata GRM1885C1H820GZ01D 1 MAX4450 PC board 2 0.1µF ±10%, 16V X7R ceramic capacitors (0603) None C4, C5 None 1 MAX4450 data sheet 10µF ±10%, 6.3V X5R ceramic capacitors (1206) Taiyo Yuden JMK316BJ106KL or TDK C3216X5R0J106KT None 1 MAX4450 EV kit data sheet C6, C7 2 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX4450 General Description The MAX4450 evaluation kit (EV kit) demonstrates the capability of the high-speed MAX4450 operational amplifier configured in a 3-pole, lowpass Sallen-Key filter which provides a Butterworth response with a bandwidth of -3dB at 5.25MHz. This circuit can be used for video anti-aliasing and reconstruction filtering. The circuit is designed to drive a 75Ω termination, common in video applications, with an overall gain of 1. The MAX4450 EV kit board operates from a ±2.25V to ±5.5V dual-voltage supply or a +4.5V to +11V single-voltage supply. The MAX4450 EV kit is a fully assembled and tested surface-mount board. Evaluates: MAX4450 MAX4450 Evaluation Kit Component Suppliers SUPPLIER A/D Electronics PHONE FAX 253-851-8005 253-858-9869 WEBSITE www.adelectronics.com Murata 770-436-1300 770-436-3030 www.murata.com Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com TDK 847-803-6100 847-390-4498 www.component.tdk.com Note: When contacting these suppliers, please indicate you are using the MAX4450. Quick Start Required Equipment: • Dual ±5.0V DC power supply • Signal generation platform (e.g., Tektronix TG 2000) • Video measurement set (e.g., Tektronix VM 700A) The MAX4450 EV kit is a fully assembled and tested surface-mount board. Follow the steps below for board operation. Do not turn on the power supply until all connections are completed. 1) Connect the output from the 75Ω video-signal generator to the INPUT BNC connector on the EV kit. 2) Connect the input of the 75Ω video measurement set to the OUTPUT BNC connector on the EV kit. 3) For dual-supply operation connect the +5V supply to the VCC pad. Connect ground to the GND pad. For single-voltage supply operation see note below. tion to an overall gain of 1. The board operates from a ±2.25V to ±5.5V dual-voltage supply or a +4.5V to +11V single-voltage supply. Test The MAX4450 circuit has been evaluated using the Tektronix TG2000 generator and VM700 measurement test setup as shown in Figure 2. The filter bandwidth and differential gain and phase were measured using the industry-standard Tektronix TG2000 and VM700 set C2 R1 INPUT R2 VCC R3 R6 R11 C1 C3 MAX4450 OUTPUT VEE 4) Connect the -5.0V supply to the VEE pad. R5 R4 5) Set the signal generator for the pattern desired. 6) Turn on the ±5.0V DC power supply. 7) Analyze the filtered-output signal with the video measurement set. Figure 1. Simplified Video Filter Circuit Note: The generator and the video test set must be 75Ω terminated. The signal source must provide a DC return to ground. If it does not, place a 1kΩ resistor at R11 to provide this. If the measuring device is highimpedance, a 75Ω resistor must be installed at R7. If a 50Ω system is used, resistor R6 must be changed to 50Ω. For single-supply (5V) operation connect VEE to ground. ±5V POWER SUPPLY TEKTRONIX TG2000 EV KIT TEKTRONIX VM700 Detailed Description The MAX4450 EV kit is a fully assembled and tested surface-mount circuit board that demonstrates the capability of the high-speed MAX4450 configured in a 3-pole, active lowpass, Sallen-Key filter circuit shown in Figure 1. The filter can be used for video anti-aliasing or as a reconstruction filter. The circuit is a Sallen-Key realization with a gain of 2V/V for driving a 75Ω termina2 NOTE: THESE MUST BE 75Ω COAXIAL CABLES SUCH AS RG-59 Figure 2. MAX4450 EV Kit Measurement Setup _______________________________________________________________________________________ MAX4450 Evaluation Kit 0 MAX450EV fig04 DIFF GAIN (°) MAX4450EV fig03 0.5 0.5 0 -0.5 -1.0 -0.5 0 1 2 3 STEP 4 5 6 0 1 2 3 STEP 4 5 6 1.0 DIFF PHASE (°) AMPLITUDE (dB) 1.0 -1.0 -1.5 0.5 0 -0.5 -1.0 -2.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 FREQUENCY (MHz) Figure 3. Multiburst Measurement of the EV Kit Circuit Figure 4. Differential Gain/Differential Phase Measurement of EV Kit Circuit for the NTSC Composite format. The results are shown in Figures 3 and 4 for multiburst and differential gain/differential phase (DG/DP), respectively. The bandwidth was measured using the HP4195A spectrum analyzer to show the out-of-band insertion loss and the results are shown in Figure 5. The bandwidth of the filter is a function of the components’ value and their tolerances but the DG/DP is indicative of the excellent gain and phase linearity of the MAX4450 itself. The linearity combined with the 175MHz large-signal bandwidth, and the 50MHz, 0.1dB large-signal bandwidth, make the MAX4450 an excellent choice for all video applications. Output The MAX4450 EV kit circuit’s output bandwidth is 5.25MHz at -3dB point and has an insertion loss greater than 20dB at 13.5MHz and greater than 40dB at 27MHz. Figure 5 illustrates the Signal Gain vs. Input Signal Frequency of the EV kit’s filtering circuit. The group delay variation across the bandwidth is 25ns or less and can be used for all of the video formats (RGB, Component, and Composite Video). To preserve the quality of the video waveform it is important that the filter’s group delay variation and the group delay differential between filters, be as low as possible. To accomplish that, some means of adjusting group delay without affecting bandwidth is required. The addition of R8 in series with C3 (see Figure 9) creates a lag-lead network. By keeping the sum of R3 and R8 approximately equal to the original R3 value, the dominant pole frequency is not affected, preserving the bandwidth. As the value of R3 increases, a “lead” term is introduced, reducing the rate of change of the phase, and consequentially, the group delay. In the circuit shown in Figure 9, the average group delay variation across the filters bandwidth for R8 = 0, and R3 = 332Ω is about 20ns at 4.5MHz (see Figure 6). Raising R8 to 31.6Ω and lowering R3 to 301Ω drops the group delay variation to about 10ns at 4.5MHz (see Figure 7), and to <3ns at 4.5MHz for R3 = 274Ω, and R8 = 59Ω (see Figure 8). This slightly affects the bandedge selectivity, <0.5dB, but the -3dB bandwidth remains unchanged, as shown in Table 1. Table 1. Group Delay Results with Varying Resistor Values RESISTOR CONFIGURATION SIGNAL FREQUENCY AT 4.5MHz R3 (Ω) R8 (Ω) AVERAGE GROUP DELAY (ns) 332 0 (shorted) 25 -2.1 301 31.6 15 -2.2 274 59 7 -2.4 SIGNAL LOSS (dB) Termination The MAX4450 EV kit circuit’s input is DC-coupled and resistor R11 insures a path to ground for the input current. When the circuit is driven from a low-impedance source, resistor R11 may be removed to make the circuit a high-impedance load for the preceding stage. Resistor R7 is used to simulate a back-terminated coax and a 75Ω resistor should be installed if an external load is not applied. _______________________________________________________________________________________ 3 Evaluates: MAX4450 DIFFERENTIAL GAIN AND PHASE MULTIBURST 1.0 GROUP DELAY AND GAIN GAIN vs. FREQUENCY -5 GAIN (dB) 0 -15 -20 -25 GROUP DELAY (ns) GAIN (dB) -10 0 -0.5 -1.0 -1.5 -2.0 -2.5 -30 -35 -40 -45 1 10 100 FREQUENCY (MHz) 30 25 20 15 10 5 0 -5 -10 MAX450EV fig06 0.5 MAX4450EV fig05 5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 FREQUENCY (MHz) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 FREQUENCY (MHz) Figure 5. Signal Gain vs. Frequency Response of the EV Kit Circuit Figure 6. Group Delay for R3 = 332Ω and R8 = 0 in the EV Kit Circuit GROUP DELAY AND GAIN GROUP DELAY AND GAIN 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 FREQUENCY (MHz) GROUP DELAY (ns) 20 15 10 5 0 -5 -10 10 8 6 4 2 0 -2 -4 -6 -8 -10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 FREQUENCY (MHz) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 FREQUENCY (MHz) FREQUENCY (MHz) Figure 7. Group Delay for R3 = 301Ω and R8 = 31.6Ω in the EV Kit Circuit 4 0 -0.5 -1.0 -1.5 2.0 -2.5 MAX450EV fig08 0.5 GAIN (dB) 0 -0.5 -1.0 -1.5 2.0 -2.5 MAX450EV fig07 GAIN (dB) 0.5 GROUP DELAY (ns) Evaluates: MAX4450 MAX4450 Evaluation Kit Figure 8. Group Delay for R3 = 274Ω and R8 = 59Ω in the EV Kit Circuit _______________________________________________________________________________________ MAX4450 Evaluation Kit 1 OUTPUT OUT VCC VEE R7 OPEN U1 R9 SHORT (PC TRACE) R1 75Ω R2 221Ω VCC VEE R3 332Ω C1 330pF 2% C4 0.1µF 3 IN+ IN- 4 C3 82pF 2% R5 604Ω R8 SHORT (PC TRACE) VCC VCC NOTE: ALL RESISTORS ARE 1% UNLESS OTHERWISE SPECIFIED. R4 604Ω 5 C5 0.1µF INPUT R11 75Ω R10 SHORT (PC TRACE) MAX4450 2 C2 100pF 2% Evaluates: MAX4450 R6 75Ω C7 10µF VEE C6 10µF VEE GND Figure 9. MAX4450 EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX4450 MAX4450 Evaluation Kit Figure 10. MAX4450 EV Kit Component Placement Guide— Component Side Figure 11. MAX4450 EV Kit PC Board Layout—Component Side Figure 12. MAX4450 EV Kit PC Board Layout—Solder Side 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. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.