APPLICATION NOTE SKY85405-11: Ruggedness Improvements in 5 V Applications Introduction This Application Note provides information on how to improve ruggedness in a 5 V application. This level can be significantly improved to greater than +12 dBm maximum input power drive by adding a 20 series resistor on Vcc2 and a 1 series resistor on Vcc3, with minimal trade-off on overall performance. The locations of the 20 and the 1 resistors are shown in Figure 1. The SKY85405-11 is rated for a maximum input power drive of +10 dBm under a voltage standing wave ratio (VSWR) of 10:1 presented to its output, but the device sometimes fails at input power of around 0 dBm when the actual Vcc = 5.25 V ~ 5.5 V. Skyworks GreenTM products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of GreenTM, document number SQ04–0074. 3 × 4 5 VCC1 2 × 6 7 × 8 9 VCC3 C20 10 μF R2 20 Ω C6 100 nF C7 100 nF 5 GND GND GND GND GND RF_IN GND 6 7 8 9 × × × × Note: 15 14 RF_OUT 13 GND 12 GND 11 EN N/C VREF1 16 J1 SMA C18 10 pF DET 4 R3 1Ω N/U N/U 3 SMA 17 N/U 2 N/C C19 10 pF J2 1 18 VCC3 PAD × 19 VCC2 20 VCC1 21 10 VDET VREF1 1 VCC2 J3 Header 10 VDET R1 26.7 kΩ R1 is used to simulate the load presented by the customer’s detector input and should not be installed on any other designs. 203840A-001 Figure 1. SKY85405-11 Schematic for Improved Ruggedness Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 203840A • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice • January 28, 2016 1 APPLICATION NOTE • SKY85405-11: RUGGEDNESS IMPROVEMENTS IN 5 V APPLICATIONS Power Dissipation Considerations Adding a series resistor on Vcc2 limits the Icc2 and Icc3 current and the voltage on pin 19 (Vcc2) as the last stage is eventually starved when the RF input exceeds saturation. Adding a series resistor on Vcc3 further limits the voltage on pin 18 (Vcc3) and the Icc3 current to protect the last stage from being over-driven. The voltage drop across the 20 resistor on Vcc2 at 0 dBm (well above the 1dB input compression point) is 1.85 V or an equivalent power dissipation of 170 mW. The voltage drop across the 1 resistor on Vcc3 at 0 dBm is 0.6 V or an equivalent power dissipation of 360 mW. The resistor should be sized appropriately to handle this power dissipation during operation conditions. The measured current and voltage at pin 19 on Vcc2 and Vcc3 are shown in Figure 2 and Figure 3, respectively. The measured current and voltage at pin 18 on Vcc2 and Vcc3 are shown in Figure 3 and Figure 4, respectively. Figure 2. Measured Current at Pin-19 with and without 20 Ω on Vcc2 and 1 Ω Resistors on Vcc3 Figure 4. Measured Current at Pin-18 with and without 20 Ω on Vcc2 and 1 Ω Resistors on Vcc3 Figure 3. Measured Voltage at Pin-19 with and without 20 Ω on Vcc2 and 1 Ω Resistors on Vcc3 Figure 5. Measured Voltage at Pin-18 with and without 20 Ω on Vcc2 and 1 Ω Resistors on Vcc3 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 2 January 28, 2016 • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice • 203840A APPLICATION NOTE • SKY85405-11: RUGGEDNESS IMPROVEMENT IN 5 V APPLICATIONS Performance Trade-Off Because the voltage at Vcc2 and Vcc3 decreases as input power or current increases, some linearity degradation is expected. Figure 6. HT20 MCS7 Dynamic EVM performance with and without 20 Ω on Vcc2 and 1Ωresistor on Vcc3 HT20 MCS7 dynamic EVM performance with and without the resistors on Vcc2 and Vcc3 is shown in Figure 6. VHT80 MCS9 dynamic EVM performance with and without the resistors on Vcc2 and Vcc3 is shown in Figure 7. Figure 7. VHT80 MCS9 Dynamic EVM performance with and without 20 Ω on Vcc2 and 1Ωresistor on Vcc3 Copyright © 2016 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 203840A • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice January 28, 2016 3