AWT6111 CDMA/AMPS Power Amplifier Application Note - Rev 0 General Description The AWT6111 is a hetero-junction bipolar transistor (HBT) amplifier designed for the CDMA cellular handset. The frequency band of operation is 824-849 MHz. The AWT6111 is designed to operate from a single lithium-ion (Li-ion) battery. The amplifier input and output are matched to provide optimum performance in a 50 Ω system. Minimal external components are required for proper RF bypassing. The tantalum capacitors, C8 and C9, are not required. Landings should be made available on the printed circuit board (PCB) as a precaution. Table 1: AWT6111 Module Pin Description PIN NAME DESCRIPTION NOTES 1 V CC1 Bias supply to 1st stage collector 3.0 - 4.2 V 2 RFIN RF Input Use 50 Ω transmission line 3 VREF Reference supply to base bias 2.75 - 3.1 V 4 VMODE Mode select 0 V for high power mode, 2.7 V for low power mode 5 V CC2 Bias supply to 2nd stage collector 3.0 - 4.2 V 6 RFOUT RF Output Use 50 Ω transmission line 7 GND Supply ground DC ground Figure 1: Application Schematic 04/2002 AWT6111 Application Board The application board was designed with GETEK material and 0.014" thickness. Figure 2: Evaluation Board Layout Notes: 1. Copper trace width is 0.0257 ±0.001". 2. Relative dielectric constant is 4.37 at 1 GHz. 3. Dielectric thickness is 0.014 ±0.001". Table 2: Parts List DESCRIPTION VALUE FUNCTION C1 0.01 uF Bypass C2 0.01 uF Bypass C4 0.01 uF Bypass C8 22 uF, tant. Bypass C9 22 uF, tant. Bypass C3, C5, C6 & C7 not used. Designations same as engineering fixture. 2 Application Note - Rev 0 04/2002 AWT6111 Minimum Bench Requirements The following minimum equipment is required for proper power amplifier operation. 1. 2. 3. 4. 5. 6. 7. Spectrum Analyzer Three power supplies CDMA function generator RF filter (Surface Acoustic Wave-SAW) Isolator RF power meter Coupler(s) Turn On Procedures Upon receiving the amplifier, the characterization sheet should be reviewed for the appropriate bias conditions. Review the evaluation board drawing prior to connection of the proper bias pins on the application board. Other Recommendations In order to maximize performance in a CDMA system, the AWT6111 achieves full output power (+28.5dBm in digital mode and +31dBm in analog mode) while operating in low power mode. This minimizes quiescent current (47 mA typical) and eliminates the need for mode switching between high and low power or between analog and digital modes of operation. Applying logic low (0 V) to both VREF and V MODE pins, places the amplifier in shutdown (standby) mode. To minimize external switch requirements, the VREF and VMODE lines can be tied together. IMODE is only ~300 uA, therefore tying it to the V REF line doesn’t significantly increase the current requirements on the switched line. 1. Be sure to connect the amplifier to 50 Ω RF in/ out cables. 2. No RF power should be applied to the amplifier prior to biasing. 3. Attach VCC1 and VCC2 first; then VREF and VMODE. 4. Turn the VREF supply to +2.85 V. Observe current draw of approximately 5 mA. 5. Turn on the VCC1 and VCC2 supply to +3.5 V. Observe current of ~100 mA from VCC supply. 6. Turn on RF power applying +5 dBm. Gradually increase until the appropriate power level is obtained from the output (28.5 - 29 dBm in digital mode, 31 dBm in analog mode). 7. Perform measurements. Layout Considerations A sufficient number of holes (QTY 12 - 0.2mm diameter plated through hole) should be placed under the module in order to channel the heat properly. In addition, contact should be made between the PA slug located under the amplifier and the board. For hand assembly of the board, place sufficient bonding paste so that contact is made between the PA and ground. For large volume assembly, please refer to the solder profile recommendations application note. For RF in and out provide 50 Ω transmission lines. Application Note - Rev 0 04/2002 3 AWT6111 ANADIGICS, Inc. 141 Mount Bethel Road Warren, New Jersey 07059, U.S.A. Tel: +1 (908) 668-5000 Fax: +1 (908) 668-5132 URL: http://www.anadigics.com E-mail: [email protected] IMPORTANT NOTICE ANADIGICS, Inc. reserves the right to make changes to its products or to discontinue any product at any time without notice. The product specifications contained in Advanced Product Information sheets and Preliminary Data Sheets are subject to change prior to a product’s formal introduction. Information in Data Sheets have been carefully checked and are assumed to be reliable; however, ANADIGICS assumes no responsibilities for inaccuracies. ANADIGICS strongly urges customers to verify that the information they are using is current before placing orders. WARNING ANADIGICS products are not intended for use in life support appliances, devices or systems. Use of an ANADIGICS product in any such application without written consent is prohibited. 4 Application Note - Rev 0 04/2002