MAX2602 Evaluation Kit ____________________________Features ♦ 1W (30dBm) Output Power at 836MHz ♦ 50Ω Inputs and Outputs ♦ +2.7V to +5.5V Supply Range ♦ 11dB Gain at 836MHz ______________Ordering Information PART MAX2602EVKIT-SO TEMP. RANGE -40°C to +85°C BOARD TYPE Surface Mount ____________________Component List _________________________Quick Start DESIGNATION QTY The following section provides instructions for setting up the MAX2602 EV kit as a 1W RF power amplifier. DESCRIPTION C1, C2 2 2pF surface-mount capacitors C3 1 10pF surface-mount capacitor C4 1 12pF surface-mount capacitor C5–C8, C11, C12 6 1000pF surface-mount capacitors C9, C11 2 0.1µF surface-mount capacitors L1 1 100nH surface-mount inductor L2 1 18.5nH surface-mount spring inductor Coilcraft A05T (Note 1) R1 1 430Ω surface-mount resistor R2 1 24Ω surface-mount resistor R3 1 0Ω resistor IN, OUT 2 Edge-mount SMA connectors U1 1 MAX2602ESA (8-pin, thermally enhanced SO) None 1 MAX2601/MAX2602 data sheet None 1 Printed circuit board Note 1: Contact Coilcraft by phone at (800) 322-2645, by fax at (847) 639-1469, or on the World Wide Web at http://www.coilcraft.com. Test Equipment Required • RF signal generator capable of at least 20dBm of output power at 836MHz • Attenuator that can handle at least 30dBm (1W) of RF power (used to protect the test equipment) • RF spectrum analyzer for use at 836MHz (alternatively, a power meter can be used) • DC power supply capable of delivering 1A at +2.7V to +5.5V Connections and Setup Follow these steps for connecting the EV kit: 1) Connect a 50Ω RF signal generator capable of supplying at least 20dBm at 836MHz to the RF input SMA connector (“IN”). Set the generator’s initial output to a much lower power (-10dBm, for instance). Keep this generator’s RF output off at this time. 2) Connect a fixed attenuator that can handle 1W of power to the output SMA connector (“OUT”). This attenuator reduces the power to the test equipment and protects it from overload. Connect this attenuator’s output to a spectrum analyzer that is set to display 836MHz. It may be possible to set a referencelevel offset on the analyzer to compensate for the attenuator. Consult your spectrum analyzer’s manual for details. 3) Set the power supply to +3.6V with a 1A current limit. Disable the output. Connect the power supply to the VC terminal on the EV kit through an ammeter. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. Evaluates: MAX2601/MAX2602 _______________General Description The MAX2602 evaluation kit (EV kit) simplifies the evaluation of the MAX2602 1W RF power transistor for 900MHz band applications. The EV kit demonstrates the MAX2602 in a 3.6V, 836MHz, 1W (30dBm) RF power amplifier for constant-envelope applications. The EV kit is shipped with a MAX2602, which contains an internal biasing diode. With a simple modification, the MAX2602 EV kit can be used to emulate the MAX2601, which does not have an internal biasing diode. Evaluates: MAX2601/MAX2602 MAX2602 Evaluation Kit 4) Connect the same power supply through a separate lead to the EV kit’s VB terminal. emitter inductance as low as possible, as excessive emitter inductance can degrade the performance of any RF common-emitter amplifier. The bottom-side contact is also the principal path for heat dissipation, and must be connected to a large ground plane. 5) Verify that all the connections are correct to avoid damaging the transistor or your test equipment. 6) Turn on the 3.6V supply. Note the supply current with the RF generator off. It should be around 100mA. Biasing Capacitors C5, C9, and C11 provide decoupling for the bias supply. The transistor’s bias current is set by the internal biasing diode’s current. This current is set by the following equation: 7) Activate the RF signal generator and slowly increase the generator’s output power to 20dBm. At this time, the supply current should be about 500mA, and the output power should be 30dBm. IB = _______________Detailed Description VB - 0.75V R1 Figure 1 is the schematic for the MAX2602 EV kit as shipped. The circuit consists of four blocks: power-supply decoupling, a bias network, and both input and output matching networks. The amplifier built on this board is biased for class AB operation at 1W of output power, and provides high efficiency. The collector current is scaled to the bias current: IC = 15IB. R3 is used as a jumper. The transistor’s base is biased through R2 and L1 (a choke). For more information on the internal biasing diode’s operation, refer to the MAX2601/MAX2602 data sheet. Supply Decoupling Circuitry and Grounding The transistor’s RF input does not present a 50Ω impedance, so a matching network is required for proper operation in a 50Ω environment. This network consists of capacitor C1 to ground, approximately 1 inch (or 2.5cm) of the 50Ω transmission line (T1), a DCblocking capacitor (C6), and a shunt capacitor at the transistor base (C4). Input Matching Network Capacitors C8 and C10 provide decoupling for VC. The collector has two separate pins: one for the VC input (connected through choke L2), and one for the RF output. The most important contact for the MAX2602 is not on the top of the board; it is the bottom-side emitter contact that is connected to ground. This contact keeps C11 1000pF R1 430Ω VB C9 0.1µF C5 1000pF L1 100nH C12 1000pF R3 0Ω L2 18.5nH R2 24Ω 3 1 C6 1000pF 4 VC C8 1000pF C7 1000pF 5 C1 2pF T1 C4 12pF OUT 8 U1 IN C10 0.1µF C3 10pF T2 C2 2pF 2, 6, 7 BACK-SIDE SLUG Figure 1. MAX2602 EV Kit Schematic 2 _______________________________________________________________________________________ MAX2602 Evaluation Kit VB C9 0.1µF C5 1000pF L1 100nH C12 1000pF L2 18.5nH R2 24Ω 3 1 C6 1000pF IN 4 5 C1 2pF T1 C4 12pF VC C8 1000pF C10 0.1µF C7 1000pF OUT 8 U1 C3 10pF T2 C2 2pF 2, 6, 7 BACK-SIDE SLUG Figure 2. MAX2602 EV Kit Schematic Without the Bias Diode Output Matching Network The RF output is taken from pin 8 and is not at 50Ω impedance, so a matching network is required. The matching network consists of a shunt capacitor at the collector (C3), a DC-blocking capacitor (C7), a 50Ω transmission line (T2), and a shunt capacitor (C2). Evaluating the MAX2602 Without the Biasing Diode To evaluate the MAX2602 without the biasing diode (functionally equivalent to the MAX2601), the 0Ω resistor (R3) must be removed, and the 430Ω resistor (R1) must be replaced by a 0Ω resistor (a short) (Figure 2). Now an external bias voltage may be connected to the EV kit’s VB input. The biasing diode is no longer connected, so the EV kit will not work without an external biasing voltage. To avoid damage to the MAX2602 in this mode, be sure to turn the VC supply on before the VB supply. When turning the part off, turn the VB supply off first and then the VC supply. External bias voltages ranging from 0V to 0.85V are typically used. _____________Layout Considerations For best results, use the MAX2602 EV kit as a layout guide. The most critical connection is the emitterground contact on the MAX2602’s bottom side. On the EV kit, this contact is made through a large (0.1 inch, 2.5mm diameter) plated through-hole in the board, located directly under the part. This contact must be soldered directly to a large ground plane, as it is the principal path for heat dissipation, as well as the lowinductance emitter ground. The MAX2602 EV kit uses its ground plane as the heatsink. _______________________________________________________________________________________ 3 Evaluates: MAX2601/MAX2602 C11 1000pF R1 0Ω Evaluates: MAX2601/MAX2602 MAX2602 Evaluation Kit 1.0" Figure 3. MAX2602 EV Kit Component Placement Guide 1.0" Figure 4. MAX2602 EV Kit PC Board Layout—Component Side 1.0" Figure 5. MAX2602 EV Kit PC Board Layout—Solder Side (ground plane and heatsink) 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. 4 _____________________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.