19-1447; Rev 2; 6/01 MAX3266/MAX3267 Evaluation Kits Features The MAX3266 and MAX3267 evaluation kits (EV kits) simplify evaluation of the MAX3266 and MAX3267 transimpedance preamplifiers. ♦ Fully Assembled and Tested The EV kits include a circuit that emulates the highspeed, zero-to-peak current input signal that would be produced by a photodiode. The kit also includes a calibration circuit that allows accurate bandwidth measurements. The MAX3266 and MAX3267 EV kits are fully assembled and tested. ♦ Calibration Circuit for Accurate Bandwidth Measurements ♦ Includes Photodiode Emulation Circuit Ordering Information PART TEMP. RANGE MAX3266EVKIT-SO 0°C to +70°C 8 SO IC PACKAGE MAX3267EVKIT-SO 0°C to +70°C 8 SO Component List DESIGNATION QTY Component Suppliers DESCRIPTION C1, C2, C4, C7, C10, C11 6 1000pF, 10% ceramic capacitors C3, C5, C6, C12–C17 9 0.1µF, 25V min, 10% ceramic capacitors C8, C9 2 33µF ±10%, 25V min tantalum capacitors AVX TAJE336K025 J1–J5 5 SMA connectors (Edge Mount) J11–J14 4 Open JU1, JU2 2 2-pin headers (0.1" centers) None 2 Shunts for JU1, JU2 L1, L2 2 Ferrite beads Murata BLM11A601S R1, R2, R9, R10 4 See Table 1 R3, R11 2 49.9Ω, 1% resistors R4, R12 2 1kΩ, 5% resistors SUPPLIER PHONE FAX AVX 843-444-2863 843-626-3123 Central Semiconductor 516-435-1110 516-435-1824 Murata 415-964-6321 415-964-8165 Zetex 516-543-7100 516-864-7630 Note: Please indicate that you are using the MAX3266/MAX3267 when contacting these component suppliers. Quick Start 1) Connect a signal source to INPUT. Set the signal amplitude to 50mVp-p (this may require some attenuation between the source and the MAX3266 EV kit.) The signal should have data rate between 500Mbps and 1250Mbps. R5 1 1kΩ potentiometer R6, R8 2 10kΩ, 5% resistors 2) Connect OUT+ and OUT- to the 50Ω inputs of a high-speed oscilloscope. R7 1 10kΩ potentiometer 3) Remove shunts from jumpers JU1 and JU2. U1 1 MAX3266CSA or MAX3267CSA (8-pin SO) 4) Connect a +3.3V supply to the VCC terminal and ground to the GND terminal. U2 1 CMPT3906 PNP transistor U3 1 MAX400CSA (8-pin SO) 5) The differential signal at the oscilloscope should be between 50mVp-p and 100mVp-p. U4 0 User-supplied optical module U5 0 User-supplied optical module VCC, +15V, GND 3 Test points None 1 MAX3266/MAX3267 evaluation kit (rev. b) circuit board None 1 MAX3266/MAX3267 data sheet Detailed Description The MAX3266 is designed to accept a DC-coupled input from a high-speed photodiode, with an amplitude of 10µA to 1mA zero-to-peak. Unfortunately, high-speed current sources are not common laboratory equipment. Also, because the MAX3266 provides a DC bias for the photodiode, it cannot be DC coupled to signal sources. ________________________________________________________________ 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 Evaluate: MAX3266/MAX3267 General Description Evaluate: MAX3266/MAX3267 MAX3266/MAX3267 Evaluation Kits To allow characterization without a photodiode, the MAX3266 EV kit provides a simple circuit that emulates a photodiode using common voltage output signal sources. The connector at INPUT is terminated with 50Ω to ground. This voltage is then AC coupled to a resistance in series with the MAX3266’s input, creating an input current. U2 and U3 form a simple DC current source that is used to apply a DC current to the input signal. The values of the series resistive elements, R1 and R2, have been carefully selected not to change the bandwidth of the transimpedance amplifier. Surface-mount resistors have parasitic capacitance that reduces their impedance at frequencies above 1GHz. The user should carefully evaluate any changes to R1 and R2 using the calibration network provided on the EV kit. Table 1 shows the recommended resistor values. Photodiode Emulation The following procedure can be used to emulate the high-speed current signal generated by a photodiode: 1) Select the desired optical power (P AVG in dBm) and extinction ratio (re). 2) Calculate the average current (IAVG), and adjust R7 and R5 to obtain it. IAVG = 10(PAVG/10 ) ρ 1000 3) Calculate the AC signal current, and adjust the signal generator to obtain it. IINPUT = 2 ✕ IAVG(re - 1) / (re + 1) For example: 1) Emulate a signal with an average power of -20dBm and an extinction ratio of 10. 2) -20dBm optical power will produce 10µA of average input current (assume photodiode responsivity of 1A/W). Install a current meter at JU1. Adjust R7 and R5 until the current is 10µA. 3) The signal amplitude is 2PAVG(re - 1) / (re + 1) = 16µA. To generate this current through the 1500Ω input resistors, set the signal source to produce an output level of 16µA ✕ 1500Ω = 24mVp-p. Noise Measurement Remove R2 before attempting noise measurements to minimize input capacitance. With R2 removed the total capacitance at the IN pin is approximately 0.5pF. Refer to the Layout Considerations section in the MAX3266/ MAX3267 data sheet for more information. Table 1. Recommended Resistor Values EVALUATION KIT R1, R9 R2, R10 MAX3266EVKIT-SO 1000Ω (0603) 510Ω (0603) MAX3267EVKIT-SO 200Ω (0402) 1020Ω (composed of two 510Ω (0402) resistors) (ρ = photodiode responsivity in A/W) Table 2. Connections, Adjustments, and Control CONTROL Supply Voltage Connection (3.0 to 5.5V, 100mA current limit) +15V Supply Voltage Connection for Photodiode Emulator Circuit (+15V, 25mA) GND Connection for Ground JU1 When shunted, the photodiode emulation circuit is active. This is a convenient location to measure the emulated photodiode current. JU2 Test Pin. Shunting JU2 disables the MAX3266/MAX3267 DC cancellation amplifier. R5 Potentiometer. Fine adjustment of the DC current input. R7 Potentiometer. Coarse adjustment of the DC current input. OUT+, OUTINPUT 2 DESCRIPTION VCC Connections for the MAX3266/MAX3267 Output Signal Input Connection for a Signal Generator _______________________________________________________________________________________ _______________________________________________________________________________________ VCC2 R8 10k R7 10k R5 1k +15V 2 2 C10 1000pF 3 1 3 1 2 1 U3 7 MAX400 4 GND VCC U5 J1 OUT- OUT+ C1 1000pF C4 1000pF INPUT 3 2 3 4 C15 0.1µF C14 0.1µF R3 49.9Ω C3 0.1µF 6 1 U2 J11 R4 1k JU1 3 2 R6 10k VCC1 R2 C2 1000pF R11 49.9Ω C15 0.1µF J12 VCC2 C11 1000pF 500Ω 1k SEE TABLE 1 FOR MAX3267 RESISTOR JU2 VALUES R1 NO GND PLANE INPUT J4 NO GND PLANE R10 R9 1 2 IN N.C. VCC U1 OUT+ GND GND FERRITE L2 J8 FERRITE L1 7 8 GND VCC U4 OUT- OUT+ 3 4 6 MAX3266 OUTMAX3267 5 4 FILTER GND 3 2 1 VCC J7 +15V J6 J5 C13 0.1µF C12 0.1µF J14 C6 0.1µF C5 0.1µF C9 33µF 25V C8 33µF 25V 1k 500Ω C17 0.1µF SEE TABLE 1 FOR MAX3267 RESISTOR VALUES R12 1k OUT- J13 J3 J10 J9 J2 OUT+ +15V VCC2 VCC1 Evaluate: MAX3266/MAX3267 +15V C7 1000µF MAX3266/MAX3267 Evaluation Kits Figure 1. MAX3266/MAX3267 EV Kits Schematic 3 Evaluate: MAX3266/MAX3267 MAX3266/MAX3267 Evaluation Kits 1.0" Figure 2. MAX3266 EV Kit Component Placement Guide 1.0" Figure 3. MAX3266 EV Kit PC Board Layout—Component Side 4 1.0" Figure 4. MAX3266 EV Kit PC Board Layout—Ground Plane _______________________________________________________________________________________ 1.0" 1.0" Figure 5. MAX3266 EV Kit PC Board Layout—Power Plane Figure 6. MAX3266 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.