19-2158; Rev 0; 9/01 MAX3271 Evaluation Kit Features ♦ Fully Assembled and Tested ♦ Includes Photodiode Emulation Circuit ♦ Calibration Circuit for Accurate Bandwidth Measurement Component Suppliers SUPPLIER PHONE FAX AVX 843-444-2863 843-626-3123 Coilcraft 847-639-6400 847-639-1469 Murata 415-964-6321 415-964-8165 Ordering Information PART TEMP. RANGE IC PACKAGE MAX3271EVKIT -40°C to +85°C Chip-On-Board Note: Please indicate that you are using the MAX3271 when contacting these component suppliers. Component List DESIGNATION QTY DESCRIPTION 4 0.01µF ±10% ceramic capacitors (0402) Murata GRM36X7R103K016A C2–C4, C9, C10 5 0.1µF ±10% ceramic capacitors (0402) Murata GRM36X5R104K010AD C7 1 10µF ±10% tantalum capacitor AVX TAJC106K010R C1, C5, C6, C8 C11 1 100pF ±10% ceramic capacitor (0402) Murata GRM36X7R102K050AD J1–J3, J6, J7 5 SMA connectors (edge-mount, round contact) Note: Cut center pin to approximately 1/16in length. JU1 1 1 × 2-pin header (0.1in centers) L1 1 56nH inductor Coilcraft 0805HS-560XKBC L2, L3 2 0Ω resistors DESIGNATION QTY R1A, R1B, R5A, R5B DESCRIPTION 4 499Ω ±1% resistors (0402) R3, R7 2 4.99kΩ ±1% resistors (0402) R4, R8 2 49.9Ω ±1% resistors (0402) TP1, J4, J5 3 Test points Digi-Key 5000K-ND U1 1 MAX3271E/D die Outside Vendor to Supply 0 1mil Au wire (8 bonds) American Fine Wire EL4-7 TS8 AW8 Outside Vendor to Supply 0 Epoxy, Ablefilm 84-1 LMI None 1 MAX3271 EV kit circuit board None 1 MAX3271 data sheet ________________________________________________________________ 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: MAX3271 General Description The MAX3271 evaluation kit (EV kit) allows complete evaluation of the MAX3271 transimpedance amplifier. The EV kit includes 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 measurement. The MAX3271 EV kit is fully assembled and tested. Evaluates: MAX3271 MAX3271 Evaluation Kit Quick Start Photodiode Emulation 1) Connect a signal source to IN (J1). Set the signal amplitude to 40mVp-p (this may require some attenuation between the source and the MAX3271 EV kit.) The signal should have a data rate of 2.5Gbps. The following procedure can be used to emulate the high-speed current signal generated by a photodiode: 2) Connect OUT+ and OUT- to the 50Ω inputs of a high-speed oscilloscope at J2 and J3. 2) Calculate the average current (IAVE, A). Set the DC current at TP1 to IAVE. 1) Select the desired optical power (PAVE, dBm) and extinction ratio (re). 3) Remove the shunt from jumper JU1. 4) Connect a +3.3V supply to the VCC terminal and ground to the GND terminal. 5) The differential signal at the oscilloscope should be between 75mVp-p and 150mVp-p. Detailed Description The MAX3271 EV kit allows characterization without a photodiode. The MAX3271 is designed to accept a DCcoupled input from a high-speed photodiode. Diode currents may have 20µAp-p to 2mAp-p AC current with a DC component from 10µA to 1mA. The high-speed current source of the photodiode is emulated on the EV kit using separate AC and DC paths. The AC signal is supplied from a standard 50Ω lab source that delivers power to an onboard termination resistor. A current is then generated from the voltage signal by a resistor with low stray capacitance. The effect of the DC photodiode current may be emulated by a current source at TP1. An isolation resistor prevents the DC source from loading the AC path. The values of the series resistive elements, R1A and R1B, have been carefully selected so that the bandwidth of the transimpedance amplifier is not altered. Surface-mount resistors have parasitic capacitance that reduces their impedance at frequencies above 1GHz. Changes to R1A and R1B must be evaluated using the calibration network. IAVE = 10(PAVE / 10) ×ρ 1000 (ρ = photodiode responsivity in A/W) 3) Calculate the AC signal current and adjust the signal generator to obtain it. r −1 IAC = 2 × IAVE × e re + 1 For example, to emulate a photodiode with an average power of -16dBm and an extinction ratio of 10: 1) -16dBm optical power will produce 25µA of average input current (assume photodiode responsivity of 1A/W). Set the DC current input to 25µA at TP1. 2) The signal amplitude is 2 IAVE (re-1)/(re+1) = 41µA. To generate this current through the 1000Ω input resistors, set the signal source to produce an output level of 41µA ✕ 1000Ω = 41mVp-p. Noise Measurement Remove R1A and R1B before attempting noise measurements to minimize input capacitance. With R1A and R1B removed, the total capacitance at the IN pin is approximately 0.85pF. Refer to the Layout Considerations section in the MAX3271 data sheet for more information. Adjustment and Control Descriptions (see Quick Start) 2 COMPONENT NAME JU1 OFFSET CORRECTION TP1 DC CURRENT INPUT FUNCTION Install a shunt on JU1 to disable offset correction. Apply DC current for photodiode emulation. _______________________________________________________________________________________ MAX3271 Evaluation Kit Evaluates: MAX3271 L1 56nH J4 VCC C11 100pF C7 10µF L2 SHORT J5 L3 SHORT GND C5 0.01µF C6 0.01µF C2 0.1µF J1 R1A 499Ω 5 4 R1 R1B 499Ω IN VCC 3 VCC IN GND 6 U1 R4 49.9Ω R3 4.99kΩ OUT+ C3 0.1µF J2 C4 0.1µF J3 7 MAX3271 TP1 OUT- C1 0.01µF JU1 1 FILTER GND 8 9 R5 C9 0.1µF J6 R8 49.9Ω R5A 499Ω R5B 499Ω C10 0.1µF J7 R7 4.99kΩ C8 0.01µF Figure 1. MAX3271 EV Kit Schematic _______________________________________________________________________________________ 3 Evaluates: MAX3271 MAX3271 Evaluation Kit 1.0" Figure 3. MAX3271 EV Kit PC Board Layout—Component Side 1.0" Figure 2. MAX3271 EV Kit Component Placement Guide— Component Side 1.0" Figure 4. MAX3271 EV Kit PC Board Layout—Ground Plane 4 _______________________________________________________________________________________ MAX3271 Evaluation Kit 1.0" Figure 5. MAX3271 EV Kit PC Board Layout—Power Plane Figure 6. MAX3271 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. Evaluates: MAX3271 1.0"