BF P640 F AN 179 High Gain , Hi gh IP3 G PS L NA us ing BF P640 F Si Ge: C Tr ans is to r Applic atio n N ote Revision: Rev 1.2, 2011.09.29 RF and P r otecti on D evic es Edition 2011-09-29 Published by Infineon Technologies AG 81726 München, Germany © Infineon Technologies AG 2011. All Rights Reserved. LEGAL DISCLAIMER THE INFORMATION GIVEN IN THIS APPLICATION NOTE IS GIVEN AS A HINT FOR THE IMPLEMENTATION OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL NOT BE REGARDED AS ANY DESCRIPTION OR WARRANTY OF A CERTAIN FUNCTIONALITY, CONDITION OR QUALITY OF THE INFINEON TECHNOLOGIES COMPONENT. THE RECIPIENT OF THIS APPLICATION NOTE MUST VERIFY ANY FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION. INFINEON TECHNOLOGIES HEREBY DISCLAIMS ANY AND ALL WARRANTIES AND LIABILITIES OF ANY KIND (INCLUDING WITHOUT LIMITATION WARRANTIES OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF ANY THIRD-PARTY) WITH RESPECT TO ANY AND ALL INFORMATION GIVEN IN THIS APPLICATION NOTE. Information For further information on technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies Office (www.infineon.com). Warnings Due to technical requirements components may contain dangerous substances. For information on the types in question please contact your nearest Infineon Technologies Office. Infineon Technologies Components may only be used in life-support devices or systems with the express written approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may be endangered. Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Application Note No. 179 Revision History: 2009-01-12, Rev 1.0 2009-01-16, Rev 1.1 2011-09-29, Rev 1.2 Previous Version: Page Subjects (major changes since last revision) 4 Correction of errors (V1.0 =>V1.1) 4 Correction of errors in „Summary Of Performance Data‟ (V1.1 => V1.2) Trademarks SIEGET® is a registered trademark of Infineon Technologies AG. Additional Information: More details about Infineon RF Transistors may be found at www.infineon.com/RF Direct link to RF Transistor Datasheets / Specifications: www.infineon.com/rf.specs For S-Parameters, Noise Parameters, SPICE models: www.infineon.com/rf.models For Application Notes: www.infineon.com/rf.appnotes Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 1 High Gain, High Third-Order Intercept Low Noise Amplifier for 1575 MHz GPS Applications using the BFP640F SiGe:C Low Noise RF Transistor Overview Infineon Technologies‟ BFP640F is a high gain, low noise Silicon-Germanium-Carbon (SiGe:C) Heterojunction Bipolar Transistor (HBT) suitable for a broad range of Low Noise Amplifier (LNA) applications. 2 This circuit is targeted for 1575 MHz „L1‟ frequency GPS applications. The LNA has high linearity / high Third Order Intercept (IP3) performance, useful in reducing the magnitude of potential spurious signals generated in the LNA by strong out-of-band signals. Additional charge storage (capacitance) is used to achieve a reduction in Third-Order distortion, with the penalty of increased turn-on / turn-off times. Reference [1] describes in detail how additional charge storage reduces Third Order product levels. Both In-Band and Out-Of-Band IP3 tests are performed, with the Out-Of-Band test being done in such a way as to enable prediction of levels of a potential spurious signal falling at the desired 1575.42 MHz GPS frequency if the amplifier is injected with signals that could be present in or around a multi-band mobile phone. Amplifier is Unconditionally Stable (1 > 1.0) from 10 MHz – 12 GHz. External parts count (not including BFP640F transistor) = 10; 5 capacitors, 3 resistors, & 2 chip inductors. All passives are „0402‟ case size. Summary Of Performance Data (T=25 C, network analyzer source power -25 dBm, VCC = 2.8 V, VCE = 2.4 V, IC=8.6 mA, ZS=ZL=50 ) Frequency * NF ** IIP3 ** OIP3 IP1dB OP1dB MHz dB[s11]2 dB[s21]2 dB[s12]2 dB[s22]2 dB dBm dBm dBm dBm 900 - 3.4 17.9 -32.5 -4.8 ----------1575 -11.8 18.4 -24.9 -11.7 0.7 +5.8 +24.2 -14.1 +3.3 1800 -18.0 13.9 -20.0 -16.0 0.7 --------2400 -15.6 14.8 - 22.3 - 5.5 0.8 --------* does not extract PCB loss. If PCB loss (at input) were extracted, noise figure would be ~ 0.1 dB lower. ** In-band IIP3 result. Turn-on time: ~ 1.5 milliseconds; Turn-Off Time ~ 30 microseconds. Please see pages 24 – 26. 3 Details of PC Board Construction PC board is fabricated from standard, low-cost “FR4” glass-epoxy material. A cross-section diagram of the PC board is given below. PCB CROSS SECTION TOP LAYER (RF TRACES) 0.010 inch / 0.254 mm INTERNAL GROUND PLANE 0.031 inch / 0.787 mm ? LAYER FOR MECHANICAL RIGIDITY OF PCB, THICKNESS HERE NOT CRITICAL AS LONG AS TOTAL PCB THICKNESS DOES NOT EXCEED 0.045 INCH / 1.14 mm (SPECIFICATION FOR TOTAL PCB THICKNESS: 0.040 + 0.005 / - 0.005 INCH; 1.016 + 0.127 mm / - 0.127 mm ) BOTTOM LAYER Application Note 4 / 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 4 TSFP-4 Package Outline & Footprint. Dimensions in millimeters (mm). Refer to BFP640F Datasheet [2] for emitter – base – collector pin assignments. Application Note 5 / 28 Rev. 1.2, 2011-09-29 Application Note 6 / 28 C1 22pF L1 22nH R1 15 ohms PCB = 640F-021904 Rev A PC Board Material = Standard FR4 C2 1.8pF C4 5.6pF C5 0.1uF ( BFP640F Vce = 2.4 V ) L2 8.2nH Q1 BFP640F SiGe:C Low Noise Transistor R2 47K R3 27 ohms J2 RF OUTPUT Inductive Emitter Degeneration (Microstrip Inductors) for IP3 improvement, Low Frequency Stability Improvement & RF matching. Width = 0.010 inch / 0.25 mm, Length = 0.035 inch / 0.89 mm J1 RF INPUT Black rectangles are 50 ohm microstrip tracks, not chip components ! C3 0.1uF Inductors L1 & L2 are Murata LQP15M Series I = 8.6 mA 5 J3 DC Connector Vcc = 2.80 V Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Schematic Diagram Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 6 Bill Of Material (BOM) Reference Designator Value C1 C2 C3 22pF 1.8pF 0.1uF C4 Manufacturer Function „0402‟ chip capacitor „0402‟ chip capacitor „0402‟ chip capacitor Various Various Various 5.6pF „0402‟ chip capacitor Various C5 0.1uF „0402‟ chip capacitor Various Input DC block Output DC block, output match Low frequency decoupling / blocking cap; improves thirdorder intercept (TOI). Please refer to Reference [1], pages RF decoupling / blocking cap; also has some influence on stability and output match Low frequency decoupling / blocking cap; improves thirdorder intercept (TOI). Please refer to Reference [1], pages L1 22nH „0402‟ case size chip inductor Murata LQP15M Series or equivalent Murata L2 8.2nH „0402‟ case size chip inductor Murata LQP15M series or equivalent Murata R1 15 „0402‟ chip resistor Various R2 R3 47k 27 „0402‟ chip resistor „0402‟ chip resistor Various Various Q1 --- J1, J2 J3 --- Application Note Description / Part # BFP640F SiGe:C Low Noise RF Transistor, TSFP-4 package Infineon Technologies RF Edge Mount SMA Female Connector, 142-0701-841 MTA-100 Series 5 pin connector 640456-5 PC Board, Part # 640F-021904 Rev A 7 / 28 RF Choke at LNA input (for DC bias to base). RF „Choke‟ at LNA output, for DC bias to collector. Also influences matching and stability. For RF stability improvement. Not a DC bias component. DC biasing (base current). DC biasing (provides DC negative feedback to stabilize DC operating point over temperature variation, transistor hFE variation, etc.) LNA active device. Emerson / Johnson Input, Output RF connector Tyco (AMP) Infineon Technologies 5 Pin DC connector header Printed Circuit Board Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 7 Scanned Images of PC Board View of Entire PC Board Application Note 8 / 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Close-In View of LNA Section Application Note 9 / 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 8 Noise Figure Measurement Data Noise Figure Plot, from Rohde and Schwarz FSEK3 + FSEM30 Rohde & Schwarz FSEK3 14 Jan 2009 Noise Figure Measurement EUT Name: Manufacturer: Operating Conditions: Operator Name: Test Specif ication: Comment: BFP640F High Linearity GPS LNA - AN179 Inf ineon Technologies T=25 C, V = 2.8 V, Vce = 2.4 V, I = 8.6 mA Gerard Wevers GPS PCB = 640F-021904 Rev A; Preamp = MITEQ SMC-02 12 January 2009 Analyzer RF Att: Ref Lvl: 0.00 dB -50.00 dBm RBW : VBW : 1 MHz 100 Hz Range: 30.00 dB Ref Lvl auto: ON Measurement 2nd stage corr: ON Mode: Direct ENR: 346A_1.ENR Noise Figure /dB 1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 1475 MHz Application Note 20 MHz / DIV 10/ 28 1675 MHz Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Noise Figure, Tabular Data Taken With Rohde & Schwarz FSEM30 + FSEK3 System Preamplifier = MITEQ SMC-02 Frequency 1475 MHz 1485 MHz 1495 MHz 1505 MHz 1515 MHz 1525 MHz 1535 MHz 1545 MHz 1555 MHz 1565 MHz 1575 MHz 1585 MHz 1595 MHz 1605 MHz 1615 MHz 1625 MHz 1635 MHz 1645 MHz 1655 MHz 1665 MHz 1675 MHz Application Note Nf 0.75 dB 0.76 dB 0.72 dB 0.73 dB 0.74 dB 0.73 dB 0.72 dB 0.73 dB 0.73 dB 0.74 dB 0.74 dB 0.71 dB 0.73 dB 0.72 dB 0.69 dB 0.74 dB 0.74 dB 0.72 dB 0.75 dB 0.73 dB 0.71 dB 11/ 28 Temp 54.6 K 55.4 K 52.3 K 53.2 K 54.2 K 53.4 K 52.1 K 52.9 K 53.4 K 54.2 K 53.5 K 51.3 K 53 K 52.4 K 50.3 K 53.9 K 53.6 K 52.2 K 54.7 K 52.9 K 51.3 K Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 9 Amplifier Compression Point Measurement Gain Compression at 1575.42 MHz, VCC = +2.8 V, I = 8.6mA, VCE = 2.4V, T = 25C: Rohde & Schwarz ZVB20 Vector Network Analyzer is set up to sweep input power to LNA in a “Power Sweep” at a fixed frequency of 1575.42 MHz. ZVB20 Port 1, which provides INPUT power to drive the LNA, has its power level calibrated with the NRP-Z21 power sensor to ensure power level accuracy with the reference plane at the RF input connector of the amplifier. X-axis of VNA screen-shot below shows input power to LNA swept from –30 to –5 dBm. Input 1 dB compression point = -14.1 dBm Output 1dB compression point = -14.1 dBm + (Gain – 1dB) = -14.1 dBm + 17.4 dB = +3.3 dBm Trc3 S21 dB Mag 1 dB / Ref 18 dB Cal int PCal Smo Offs 3 of 4 (Max) M 1 -29.14 dBm • M 2 -14.06 dBm S21 18.417 dB 17.416 dB 20 19 M1 18 M2 17 16 15 14 13 12 Ch1 Start -30 dBm Freq 1.57542 GHz Stop -5 dBm 1/12/2009, 10:25 PM Application Note 12/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 10 Amplifier Stability, Gain, Return Loss and Reverse Isolation Plots Rohde and Schwarz ZVB Network Analyzer Calculates and plots stability factor “1” of the BFP640F amplifier in real time. Stability Factor 1 1 is defined as follows [1]: 1 - |S11|2 = | S22 – S11* det(S) | + |S21S12| The necessary and sufficient condition for Unconditional Stability is 1 > 1.0. In the plot, 1 > 1.0 over 10 MHz – 12 GHz; amplifier is Unconditionally Stable over 10 MHz – 12 GHz frequency range. Trc3 µ1 Lin Mag 100 mU/ Ref 1 U Cal Smo Offs 3 of 4 (Max) • M 1 1.975420 GHz 1.0320 M 2 900.00000 MHz 1.2660 M 3 1.800000 GHz 1.0449 M 4 2.400000 GHz 1.0532 µ1 1700 U U U U 1600 1500 1400 M 1300 2 1200 1100 MM3 1M 4 1000 900 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:58 AM [1]. “Fundamentals of Vector Network Analysis”, Michael Hiebel, 4th edition 2008, pages 175 – 177, ISBN 978-3-939837-06-0 Application Note 13/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Input Return Loss, Log Mag 10 MHz – 12 GHz Sweep Trc3 S11 dB Mag 5 dB / Ref 0 dB Cal Smo Offs 3 of 4 (Max) M 1 1.575420 GHz -11.799 M 2 900.00000 MHz -3.4089 M 3 1.800000 GHz -15.208 • M 4 2.400000 GHz -15.610 S11 10 dB dB dB dB 5 0 M2 -5 -10 M1 M3 M4 -15 -20 -25 -30 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:55 AM Application Note 14/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Input Return Loss, Smith Chart Reference Plane = Input SMA Connector on PC Board 10 MHz – 12 GHz Sweep Trc3 S11 Smith Ref 1 U Cal Smo Offs 3 of 4 (Max) 1 S11 M1 33.486 -j14.511 6.962 2 M 2 900.00000 MHz 44.208 -j85.353 2.072 M 3 1.800000 GHz 38.358 -j10.375 5 8.522 • M 4 2.400000 GHz 41.066 -j12.458 5.323 0.5 0 0.2 0.5 1 1.575420 GHz 2 5 Ω Ω pF Ω Ω pF Ω Ω pF Ω Ω pF 10 MM3 4 M1 -5 M2 -0.5 -2 -1 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:55 AM Application Note 15/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Forward Gain. Input / Output Matching Circuits of LNA reduce gain in 2.4 – 2.5 GHz band. 10 MHz – 12 GHz Sweep Trc3 S21 dB Mag 10 dB / Ref 0 dB S21 13 M 2 MM 20 Cal Smo Offs 3 of 4 (Max) M 1 1.575420 GHz 18.379 M 2 900.00000 MHz 17.893 M 3 1.800000 GHz 17.522 • M 4 2.400000 GHz 14.750 M4 dB dB dB dB 10 0 -10 -20 -30 -40 -50 -60 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:56 AM Application Note 16/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Reverse Isolation 10 MHz – 12 GHz Sweep Trc3 S12 dB Mag 10 dB / Ref 0 dB Cal Smo Offs 3 of 4 (Max) M 1 1.575420 GHz -24.897 M 2 900.00000 MHz -32.494 M 3 1.800000 GHz -23.854 • M 4 2.400000 GHz -22.304 S12 20 dB dB dB dB 10 0 -10 MM 13 -20 -30 M4 M2 -40 -50 -60 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:56 AM Application Note 17/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Output Return Loss, Log Mag 10 MHz to 12 GHz Sweep Trc3 S22 dB Mag 5 dB / Ref 0 dB Cal Smo Offs 3 of 4 (Max) M 1 1.575420 GHz -11.705 M 2 900.00000 MHz -4.7874 M 3 1.800000 GHz -8.3500 • M 4 2.400000 GHz -5.4592 S22 10 dB dB dB dB 5 0 M2 M4 -5 M3 -10 M1 -15 -20 -25 -30 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:57 AM Application Note 18/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Output Return Loss, Smith Chart Reference Plane = Output SMA Connector on PC Board 10 MHz to 12 GHz Sweep Trc3 S22 Smith Ref 1 U Cal Smo Offs 3 of 4 (Max) 1 S22 M1 43.356 -j24.148 4.184 2 M 2 900.00000 MHz 18.959 -j30.665 5.767 M 3 1.800000 GHz 34.326 -j30.637 5 2.886 • M 4 2.400000 GHz 17.108 -j16.684 3.975 0.5 0 0.2 0.5 1 1.575420 GHz 2 5 Ω Ω pF Ω Ω pF Ω Ω pF Ω Ω pF 10 M1 M4 M3 -5 M2 -0.5 -2 -1 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 1/12/2009, 4:57 AM Application Note 19/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 11 Amplifier In-Band Third Order Intercept (TOI) Measurement In-Band Third Order Intercept (IIP3) Test. Input Stimulus: f1=1575 MHz, f2=1576 MHz, - 20 dBm each tone. Input IP3 = -20 + (51.5 / 2) = +5.8 dBm. Output IP3 = +5.8 dBm + 18.4 dB gain = +24.2 dBm. Application Note 20/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 12 Amplifier Out-Of-Band Third Order Intercept Measurement Amplifier Two-Tone Test (Third Order Product which falls @ GPS L1 Frequency 1575.42 MHz): This test is a check for a Third-Order distortion product which falls on top of desired GPS “L1” frequency of 1575.42 MHz. Input Tones are as follows: f1 = L1 + 138 MHz = 1713.42 MHz, -16 dBm f2 = L1 + 276 MHz = 1851.42 MHz, -16 dBm One third order product (2f1-f2) generated in the LNA due to the amplifier third-order nonlinearities can fall right at the desired 1575.42 MHz frequency, as follows: 2f1 – f2 = 2(1713.42MHz) – 1851.42 MHz = 1575.42 MHz Photo of Input Test Tones, from signal generators f1 = 1713.42 MHz P = -16.0 dBm Application Note f2 = 1851.42 MHz P = -16.0 dBm 21/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 Photo below shows partial output spectrum of the LNA after being driven by test tones shown on previous page. Markers are placed at the peak input tone and the “Left Hand” Third Order Product which falls at 1575 MHz. The difference in amplitudes (“delta”) is read. Note the product 2f 1 – f2 is 54.2 dB below the input test tone. The Input Third Order Intercept (IIP3) with respect to the left-side IM product at 1575.42 MHz is as follows: IIP3 = -16 dBm + (43.3 / 2) = +5.7 dBm. 2f1 – f2 product falls on GPS frequency of 1575.42 MHz Application Note 22/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 This additional image below shows the partial output spectrum of the LNA subjected to the input test tones shown two pages back, however the markers are placed at the peak tone and the “Right Hand” Third Order Product which falls at 1989.42 MHz. This “right-hand side” product is likely less relevant to GPS receivers as it is “far away” (in terms of frequency) from the desired “L1” GPS frequency of 1575.42 MHz. Note the product 2f2 – f1 is 37.2 dB below the input test tone. The Input Third Order Intercept (IIP3) with respect to the right-side IM3 product at 1989.42 MHz is as follows: IIP3 (right side) = -16 dBm + (37.2 / 2) = +2.6 dBm. 2f2 – f1 product Application Note 23/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 13 Amplifier Turn-On / Turn-Off Time Measurements The amplifier is tested for turn-on / turn-off time. See diagram below. The RF signal generator runs continuously at a power level sufficient to drive the output of the LNA to approximately 0 dBm when the LNA has DC power ON. Agilent DSO6104A Digital Oscilloscope +Vcc to amplifier „Scope Probe +DC Pin Amplifier 3 dB Attenuator Pad RF Signal Generator Agilent 8473B Detector Ch. 1 (Trigger, edge) 1 Megaohm input Z Ch. 2 ( 1 Megaohm or 50 ohm input Z) ! Note ! It may be necessary to set Ch. 2 Input Impedance to 50 ohms instead of 1M ohm. 1M ohm setting may not allow detector to discharge rapidly, depending on detector type and detector‟s output capacitance, and might give erroneous results to turn-off time measurement, e.g. could indicate excessively long turn-off times. The user can test turnoff time with Ch. 2 input impedance set to 1M ohm and then 50 ohms and see if the two results differ. 1. Signal Generator set such that output power of Amplifier is ~ 0 dBm when LNA is powered ON 2. Channel 1 of oscilloscope monitors input power supply voltage to Amplifier (+1.8, +2.8 or +3.0 volts ON, depending on the amplifier, and 0 volts when OFF). Hook oscilloscope probe to +Vcc pin on amplifier to monitor Vcc rising / falling edge. 3. Channel 2 of oscilloscope monitors rectified RF output of Amplifier 4. To make measurement of turn-on time, leave DC power supply on, disconnect and “ground” +Vcc line to discharge amplifier, then insert Vcc line back into power supply. This method will eliminate turn on time transient of power supply itself. Set up trigger of O‟Scope to trigger on rising edge of Ch.1 5. To make measurement of turn-off time, with supply ON, reset o‟scope, setup trigger to trigger on falling edge of Ch. 1, and simply remove +Vcc line / wire from the power supply input to turn amplifier OFF. Application Note 24/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 a) Turn On Time: Refer to oscilloscope screen-shot below. Upper trace (yellow, Channel 1) is DC power supply turn-on step waveform whereas lower trace (green, Channel 2) is rectified RF output signal of the LNA stage. Amplifier turn-on time is aproximately 1.5 milliseconds, or 1500 microseconds. Main source of time delay in the LNA turn-on and turn-off events are the R-C time constants formed by (R2 + R3) x C4 and R3 x C5. Additional Charge Storage (e.g. relatively large values of C3 and C5) help to reduce Third-Order distortion levels but increase turn-on / turn-off times of the amplifier. (Please refer to Schematic diagram on page 6). Application Note 25/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 b) Turn-Off Time: Rectified RF output signal (lower green trace) takes approximately ~ 30 microseconds to settle out after power supply is turned off. Application Note 26/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 14 References [1]. “A High IIP3 Low Noise Amplifier for 1900 MHz Applications Using the SiGe BFP620 Transistor”. Applied Microwave and Wireless, July 2000. The article explains how additional charge-storage (capacitance) placed across base-emitter and collector-emitter junctions can reduce the levels of thirdorder products generated during a two-tone intermodulation test; refer to the section entitled “Effect of adding additional charge storage across the base-emitter junction” on pages 3 and 4. [2]. BFP640F Datasheet, Infineon Technologies AG. Application Note 27/ 28 Rev. 1.2, 2011-09-29 Application Note No. 179 BFP640F High Linearity 1575 MHz GPS LNA with 18 dB Gain, > +5 dBm IIP3 w w w . i n f i n e o n . c o m AN179 Published by Infineon Technologies AG Application Note 28/ 28 Rev. 1.2, 2011-09-29