OM7691/BFU730F,598

AN11007 Single stage 5-6 GHz WLAN LNA with BFU730F Rev. 2 — 20 November 2012 Application note document information Info Content Keywords BFU730F, LNA, 802.11a & 802.11n MIMO WLAN Abstract The document provides circuit, layout, BOM and performance information on 5-6 GHz band LNA equipped with NXP’s BFU730F wide band transistor. This Application note is related to evaluation board OM7691/BFU730F,598 12nC 934065628598 AN11007 NXP Semiconductors 5-6 GHz LNA Revision history Rev Date Description 1 20110104 Initial document. 2 20121120 Chapter added about switching time. Contact information For additional information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 2 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 1. Introduction The BFU730F is a discrete HBT that is produced using NXP Semiconductors’ advanced 110 GHz fT SiGe:C BiCmos process. SiGe:C is a normal silicon germanium process with the addition of Carbon in the base layer of the NPN transistor. The presence of carbon in the base layer suppresses the boron diffusion during wafer processing. This allows steeper and narrower SiGe HBT base and a heavier doped base. As a result, lower base resistance, lower noise and higher cut off frequency can be achieved. The BFU730F is one of a series of transistors made in SiGe:C. BFU710F; BFU760 and BFU790 are the other types, BFU710 is intended for ultra low current applications. The BFU760F and BFU790F are high current types and are intended for application where linearity is key. The BFU7XXF are ideal in all kind of applications where cost matters. It also gives design flexibility. 2. Requirements and design of the 5-6 GHz WLAN LNA The circuit shown in this application note is intended to demonstrate the performance of the BFU730 in a 5-6 GHz LNA for e.g. 802.11 & 802.11n “MIMO” WLAN applications. Key requirements for this application as are: • NF • Gain • Turn on turn of time • Linearity. The target for this circuit is listed in table 1. Table 1. Target spec. Target specification of the 5-6GHz LNA. Vcc Icc NF Gain IRL ORL 3 10 15 >10 >10 V mA dB dB dB dB 3. Design The 5-6 GHz LNA consists of one stage BFU730F amplifier. For this amplifier 12 external components are used, for matching, biasing and decoupling. The design has been conducted using Agilent’s Advanced Design System (ADS). The 2D EM Momentum tool has been used to co simulate the PCB see Fig 1. Results are given in paragraph 4.5. The LNA shows a Gain of 14 dB @5.5 GHz, NF of 1.3 dB, with only 10 mA it shows a high input P1 dB compression of –7.5 dBm, as well as a input IP3 of +10 dBm. Finally the LNA is unconditional stable 10 MHz-20 GHz. AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 3 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 3.1 BFU730F 5-6 GHz-ADS Simulation circuit Fig 1. ADS simulation circuit for 5-6 GHz WLAN LNA AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 4 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 3.2 BFU730F 5-6 GHz - ADS Gain and match simulation results Fig 2. ADS Gain and match simulation results for 5-6 GHz WLAN LNA AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 5 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 3.3 BFU730F 5-6 GHz-ADS NF simulation Fig 3. ADS Noise Figure simulation results of 5-6 GHz WLAN LNA AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 6 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 3.4 BFU730F 5-6 GHz-ADS Stability simulation As K≥1 and Mu≥1, the LNA is unconditionally stable for the whole frequency band Fig 4. ADS stability simulation results of 5-6 GHz WLAN LNA AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 7 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 4. Implementation 4.1 Schematic R2 R3 C4 GND Vcc GND R1 L3 C3 C5 L2 RF_INPUT RF_OUTPUT R4 C2 L4 C6 C1 C7 L1 Fig 5. 5-6 GHz LNA schematic (019aab113) AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 8 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 4.2 Layout and assembly Fig 6. AN11007 Application note Layout and assembly info of 5-6 GHz LNA All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 9 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA Table 2. Bill of materials Designator Description Size Q1 2X2 mm BFU730F PCB Value Type Note NXP Semiconductors HBT 20X35 mm C1,C7 Capacitor 0402 3.9 pF MurataGRM1555 input/output match C2,C6 Capacitor 0402 0.75 pF MurataGRM1555 input/output match C3 Capacitor 0402 15 nF MurataGRM1555 C4 Capacitor 0402 1.5 pF MurataGRM1555 C5 Capacitor 0402 1.5 pF MurataGRM1555 L1,L4 Inductor 0402 1.5 nH Murata LQP15 input/output match L2 Inductor 0402 9.1 nH Murata LQW15 input match L3 Inductor 0402 5.1 nH Murata LQW15 output match R1 Resistor 0402 37 K Bias Setting R2 Resistor 0402 100 Ohm Bias Setting Hfe and Temp spread cancellation R3 Resistor 0402 10 Ohm Stability R4 Resistor 0402 0 Ohm NA X1,X2 SMA RF connector - Johnson, End launch SMA 142-0701-841 RF input/ RF output X3 DC header - Molex, PCB header, Right Angle, 1 row, 3 way 901210763 Bias connector 4.3 PCB layout. A good PCB Layout is an essential part of an RF circuit design. The EVB of the BFU730 can serve as a guideline for laying out a board using either the BFU730 or one of the other SiGe.C HBTs in the SOT343F package. Use controlled impedance lines for all high frequency inputs and outputs. Bypass VCC with decoupling capacitors, preferable located as close as possible to the device. For long bias lines it may be necessary to add decoupling capacitors along the line further away from the device. Proper grounding the emitters is also essential for the performance. Either connect the emitters directly to the ground plane ore through vias, or do both. The material that has been used for the EVB is FR4 using the stack shown in Fig 7. AN11007 Application note All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 10 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA (1) Material supplier is Isola Duraver; Er=4.6-4.9 Tδ=0.02 Fig 7. PCB material stack 4.4 LNA View Fig 8. AN11007 Application note 5-6 GHz LNA EVB All information provided in this document is subject to legal disclaimers. Rev. 2 — 20 November 2012 © NXP B.V. 2012. All rights reserved. 11 of 23 AN11007 NXP Semiconductors 5-6 GHz LNA 4.5 Measurement results Table 3. Typical measurement results measured on the evaluation board. Temp=25 °C, frequency is 5.5 GHz unless otherwise specified. Parameter Symbol Value Unit Supply Voltage Vcc 3 V Supply Current Icc 10 mA Noise Figure NF 1.3 dB 15.8 dB 14.7 dB 13.7 dB [1] 5.0 GHz Power Gain 5.5 GHz GP 6.0 GHz Input return Loss IRL 12 dB Output return Loss ORL 13.5 dB Input 1 dB Gain compression Point Pi1dB -7.5 dBm Output 1 dB Gain compression Point Po1dB +6.5 dBm Input third order intercept point IP3i +10 dBm Output third order intercept point IP3o +24 dBm Ton 160 µs Toff 28 ns Remarks Power settling time [1] The NF and Gain figures are being measured at the SMA connectors of the evaluation board, so the losses of the connectors and the PCB of approximately 0.1dB are not subtracted. 4.5.1 Faster switching time.