Application Note, Rev. 1.1, May 2009 Application Note No. 170 BFR740L3RH SiGe:C Ultra Low Noise RF Transistor in 5 – 6 GHz LNA Application with 14 dB Gain, 1.3 dB Noise Figure & < 100 nanosecond Turn-On / Turn-Off Time TSLP-3-9 Pb-Free / Halogen Free Transistor Package (For 802.11a & 802.11n “MIMO” Wireless LAN Applications) RF & Protection Devices Edition 2009-05-11 Published by Infineon Technologies AG 81726 München, Germany © Infineon Technologies AG 2008. 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. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Application Note No. 170 Revision History: 2008-12-03, Rev 1.0 2009-05-11, Rev 1.1 Previous Version: Page Subjects (major changes since last revision) 7 Value of C2 in Bill Of Material corrected (1.0 => 1.2pF) 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. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 1 BFR740L3RH SiGe:C Ultra Low Noise RF Transistor in 5 – 6 GHz LNA Application with 14 dB Gain, 1.3 dB Noise Figure & < 100 nanosecond Turn-On / Turn-Off Time Overview • Infineon Technologies BFR740L3RH is a high gain, ultra low noise Silicon-Germanium-Carbon (SiGe:C) HBT device suitable for a wide range of Low Noise Amplifier (LNA) applications. 2 • The circuit shown in this document is targeted for 802.11a & 802.11n “MIMO” applications in the Wireless Local Area Network (WLAN) market, particularly for Access Points (AP’s) which require external LNA’s to fulfill high-sensitivity / low Bit Error Rate (BER) / long range requirements. LNA’s for this application must be able to switch on / off within about 1 microsecond, or 1000 nanoseconds. Charge storage (capacitance) used in the circuit is minimized to reduce turn-on / turn-off times. Trade-off for reduced capacitance values is a reduction in Third Order Intercept (IP3) performance. Amplifier is Unconditionally Stable (µ1 > 1.0) from 10 MHz – 12 GHz. • External parts count (not including BFR740L3RH transistor) = 12; 6 capacitors, 3 resistors, & 3 chip inductors. All passives are ‘0402’ case size. BFR740L3RH leadless transistor package is RoHS – compliant, free of any Halogen-compounds, and is 1 x 0.6 x 0.31mm in size. Summary Of Performance Data (T=25 °C, network analyzer source power ≈ -25 dBm, VCC = 3.0 V, VCE = 2.2 V, IC=12.9 mA, ZS=ZL=50 Ω ) Frequency * NF ** IIP3 ** OIP3 IP1dB OP1dB MHz dB[s11]2 dB[s21]2 dB[s12]2 dB[s22]2 dB dBm dBm dBm dBm 5150 14.6 1.3 - 13.2 -20.7 -12.8 --------5470 14.3 1.3 -19.5 -20.3 -12.7 +4.1 +18.4 -5.2 +8.1 5825 13.9 1.4 -18.0 -20.0 -16.0 --------2500 0.9 --- 2.9 - 44.1 - 0.6 --------* does not extract PCB loss. If PCB loss (at input) were extracted, noise figure would be ~ 0.2 dB lower. Note: reverse isolation ( dB[s12]2 ) when DC power to LNA is OFF = -11.5 dB @ 5470 MHz. See page 18. 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 0.012 inch / 0.305 mm TOP LAYER INTERNAL GROUND PLANE 0.028 inch / 0.711 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 / 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 4 TSLP-3-9 Package Outline & Footprint. Dimensions in millimeters (mm). Note this package does not contain any Halogen compounds in addition to being RoHS – compliant. Application Note 5 / 24 Rev. 1.1, 2009-05-11 Application Note 6 / 24 C1 0.3pF RF INPUT C3 1.5pF C2 1.2pF L1 6.8nH R2 33K L2 R1 22 ohms R3 39 ohms C5 1.5pF C6 0.3pF cc = J2 RF OUTPUT 3.0 V = 50 ohm microstripline L3 1.3nH C4 33pF I = 12.9 mA Q1: VCE = 2.2 V Q1 1.1nH BFR740L3RH SiGe:C Transistor PCB = 740L3RH-080923 Rev A PC Board Material = Standard FR4 J1 6 capacitors 3 inductors 3 resistors 12 external passives used: V 5 Inductors are Murata LQP15M Series (formerly LQP10A) 0402 case size. Capacitors and resistors are 0402 case size. J3 DC Connector Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Schematic Diagram Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 6 Bill Of Material (BOM) Reference Designator Value C1 0.3pF C2 C3 C4 C5 1.2pF 1.5pF 33pF 1.5pF C6 0.3pF L1 6.8nH 6.8nH ‘0402’ case size chip inductor Murata LQP15M Series or equivalent Murata L2 1.1nH 1.1nH ‘0402’ case size chip inductor Murata LQP15M series or equivalent Murata L3 1.3nH 1.3nH ‘0402’ case size chip inductor Murata LQP15M series or equivalent Murata R1 R2 R3 22Ω 33kΩ 39Ω ‘0402’ chip resistor ‘0402’ chip resistor ‘0402’ chip resistor Various Various Various Q1 --- J1, J2 J3 --- Application Note Description / Part # Manufacturer 0.3pF, 50V, COG ‘0402’ case size capacitor Murata GRM1555C1HR30BZ01D or equivalent ‘0402’ chip capacitor ‘0402’ chip capacitor ‘0402’ chip capacitor ‘0402’ chip capacitor 0.3pF, 50V, COG ‘0402’ case size capacitor Murata GRM1555C1HR30BZ01D or equivalent BFR740L3RH SiGe:C Low Noise RF Transistor, TSLP-3-9 package RF Edge Mount SMA Female Connector, 142-0701-841 MTA-100 Series 5 pin connector 640456-5 PC Board, Part # 740L3RH-080923 Rev A 7 / 24 Murata, AVX, etc. Various Various Various Various Murata, AVX, etc. Infineon Technologies Function Input Match Input DC block, Input Matching RF decoupling / blocking cap RF decoupling / blocking cap RF decoupling / blocking cap Output DC block and output matching. Also influences input match. 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. Output matching; also influences input match. For RF stability improvement. DC biasing (base). 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. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 7 Scanned Images of PC Board View of Entire PC Board Application Note 8 / 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Close-In View of LNA Section Application Note 9 / 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 8 Noise Figure Measurement Data Noise Figure Plot, from Rohde and Schwarz FSEK3 + FSEM30 Rohde & Schwarz FSEK3 02 Dec 2008 Noise Figure Measurement EUT Name: Manufacturer: Operating Conditions: Operator Name: Test Specification: Comment: BFR740L3RH 5 - 6 GHz LNA, Fast Switching / Fast Turn ON-OFF Time Infineon Technologies T=25 C, V = 3.0V, Vce = 2.2V, I = 12.9mA Gerard Wevers WLAN 802.11n, 802.11n PCB = 740L3RH-080923 Rev A; Preamp = MITEQ AFS3-04000800-10-ULN 2 December 2008 Analyzer RF Att: Ref Lvl: 0.00 dB -45.00 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 1.90 1.80 1.70 1.60 1.50 1.40 1.30 1.20 1.10 1.00 0.90 4800 MHz Application Note 120 MHz / DIV 10/ 24 6000 MHz Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Noise Figure, Tabular Data Taken With Rohde & Schwarz FSEM30 + FSEK3 System Preamplifier = MITEQ 4 – 8 GHz LNA Frequency 4800 MHz 4850 MHz 4900 MHz 4950 MHz 5000 MHz 5050 MHz 5100 MHz 5150 MHz 5200 MHz 5250 MHz 5300 MHz 5350 MHz 5400 MHz 5450 MHz 5500 MHz 5550 MHz 5600 MHz 5650 MHz 5700 MHz 5750 MHz 5800 MHz 5850 MHz 5900 MHz 5950 MHz 6000 MHz Application Note Nf 1.35 dB 1.34 dB 1.32 dB 1.33 dB 1.31 dB 1.32 dB 1.33 dB 1.31 dB 1.27 dB 1.29 dB 1.30 dB 1.30 dB 1.28 dB 1.29 dB 1.29 dB 1.28 dB 1.28 dB 1.31 dB 1.31 dB 1.32 dB 1.36 dB 1.35 dB 1.36 dB 1.35 dB 1.39 dB 11/ 24 Temp 105.3 K 104.5 K 103 K 104.3 K 102 K 102.9 K 103.8 K 102.4 K 98.3 K 100.4 K 101.6 K 101.3 K 99.7 K 100.4 K 99.9 K 99.8 K 99.3 K 101.9 K 101.7 K 103.3 K 107.1 K 105.7 K 106.7 K 105.5 K 109.5 K Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 9 Amplifier Compression Point Measurement Gain Compression at 5470 MHz, VCC = +3.0 V, I = 12.9mA, VCE = 2.2V, T = 25°C: Rohde & Schwarz ZVB20 Vector Network Analyzer is set up to sweep input power to LNA at a fixed frequency of 5470 MHz. X-axis of VNA screen-shot below shows input power to LNA being swept from –30 to 0 dBm. ZVB20 Port 1 output power is checked / verified against HP E4419A power meter; ZVB20 output power is ≅ 0.6 dB lower than indicated on ZVB20 due to test cable loss. Therefore, a 0.6 dB offset is needed. Input 1 dB compression point = - 4.6 dBm – 0.6 dB offset = - 5.2 dBm Output 1dB compression point = - 5.2 dBm + (Gain – 1dB) = -5.2 dBm + 13.3 dB = +8.1 dBm Trc1 S21 dB Mag 1 dB / Ref 14 dB Cal Smo Offs 1 M 1 -21.52 dBm • M 2 -4.64 dBm S21 15 14.342 dB 13.343 dB M1 14 M2 13 12 11 10 9 8 7 Ch1 Start -30 dBm Freq 5.47 GHz Stop 0 dBm 12/2/2008, 8:15 AM Application Note 12/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 10 Amplifier Stability, Gain, Return Loss and Reverse Isolation Plots µ”: Amplifier Stability - Plot of Stability Factor “ 1 Rohde and Schwarz ZVB Network Analyzer Calculates and plots stability factor “µ1” of the BFP740F amplifier in real time. Stability Factor µ1 is defined as follows [1]: µ 1 - |S11|2 1 = | S22 – S11* det(S) | + |S21S12| The necessary and sufficient condition for Unconditional Stability is µ1 > 1.0. In the plot, µ1 > 1.0 over 10 MHz – 12 GHz; amplifier is Unconditionally Stable over 10 MHz – 12 GHz frequency range. Trc1 µ1 Lin Mag 100 mU/ Ref 1 U Cal Smo Offs 1 M1 •M 2 M3 M4 µ1 1800 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz 1.2361 1.3018 1.3886 1.0437 U U U U 1700 1600 1500 M3 1400 M2 1300 M1 1200 1100 M4 1000 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:27 AM [1]. “Fundamentals of Vector Network Analysis”, Michael Hiebel, 4th edition 2008, pages 175 – 177, ISBN 978-3-939837-06-0 Application Note 13/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Input Return Loss, Log Mag 10 MHz – 12 GHz Sweep Trc1 S11 dB Mag 5 dB / Ref 0 dB Cal Smo Offs 1 M1 •M 2 M3 M4 S11 10 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz -13.228 -19.490 -17.962 -2.9201 dB dB dB dB 5 0 M4 -5 -10 M1 -15 M3 M2 -20 -25 -30 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:23 AM Application Note 14/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Input Return Loss, Smith Chart Reference Plane = Input SMA Connector on PC Board 10 MHz – 12 GHz Sweep Trc1 S11 Smith Ref 1 U Cal Smo Offs 1 1 S11 M 1 5.150000 GHz 0.5 M1 M2 0 0.2 0.5 1 M3 45.694 j20.880 645.27 2 • M 2 5.470000 GHz 55.774 j9.9060 288.22 M 3 5.825000 GHz 56.335 -j12.290 5 2.223 M 4 2.500000 GHz 9.9260 -j21.677 2.937 2 5 Ω Ω pH Ω Ω pH Ω Ω pF Ω Ω pF -5 M4 -0.5 -2 -1 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:24 AM Application Note 15/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Forward Gain. Input / Output Matching Circuits of LNA reduce gain in 2.4 – 2.5 GHz band. 10 MHz – 12 GHz Sweep Trc1 S21 dB Mag 5 dB / Ref 0 dB S21 Cal Smo Offs M1 M 2M 3 15 1 M1 •M 2 M3 M4 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz 14.617 14.312 13.855 0.9331 dB dB dB dB 10 5 M4 0 -5 -10 -15 -20 -25 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:24 AM Application Note 16/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Reverse Isolation 10 MHz – 12 GHz Sweep Trc1 S12 dB Mag 10 dB / Ref 0 dB Cal Smo Offs 1 M1 •M 2 M3 M4 S12 10 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz -20.708 -20.307 -19.968 -44.102 dB dB dB dB 0 -10 M 2M 3 M1 -20 -30 M4 -40 -50 -60 -70 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:25 AM Application Note 17/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Reverse Isolation, AMPLIFIER DC POWER TURNED OFF. 10 MHz – 12 GHz Sweep Trc1 S12 dB Mag 10 dB / Ref 0 dB Cal Smo Offs 1 M1 •M 2 M3 M4 S12 10 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz -12.281 -11.468 -10.070 -34.638 dB dB dB dB 0 M 2M 3 M1 -10 -20 M4 -30 -40 -50 -60 -70 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 5:19 AM Application Note 18/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Output Return Loss, Log Mag 10 MHz to 12 GHz Sweep Trc1 S22 dB Mag 5 dB / Ref 0 dB Cal Smo Offs M1 •M 2 M3 M4 S22 5 M4 0 1 5.150000 5.470000 5.825000 2.500000 GHz GHz GHz GHz -12.819 -12.729 -16.030 -0.5780 dB dB dB dB -5 -10 M2 M1 M3 -15 -20 -25 -30 -35 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:25 AM Application Note 19/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time Output Return Loss, Smith Chart Reference Plane = Output SMA Connector on PC Board 10 MHz to 12 GHz Sweep Trc1 S22 Smith Ref 1 U Cal Smo Offs 1 1 S22 M 1 5.150000 GHz 0.5 M1 04 M 0.2 0.5 1 M2 65.899 j22.074 682.17 2 • M 2 5.470000 GHz 79.719 -j4.3934 6.623 M 3 5.825000 GHz 53.714 -j16.123 5 1.695 M 4 2.500000 GHz 1.6559 -j1.5542 40.962 2 5 Ω Ω pH Ω Ω pF Ω Ω pF Ω Ω pF M3 -5 -0.5 -2 -1 Ch1 Start 10 MHz Pwr -25 dBm Stop 12 GHz 12/3/2008, 3:26 AM Application Note 20/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 11 Amplifier Third Order Intercept (TOI) Measurement In-Band Third Order Intercept (IIP3) Test. Input Stimulus: f1=5470 MHz, f2=5471 MHz, -20 dBm each tone. Input IP3 = -20 + (48.1 / 2) = +4.1 dBm. Output IP3 = +4.1 dBm + 14.3 dB gain = +18.4 dBm. Application Note 21/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time 12 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 +3 Volts Ch. 1 (Trigger, edge) 1 Megaohm input Z Amplifier 3 dB Attenuator Pad Signal Generator f=5470 MHz Agilent 8473B Detector Ch. 2 (50 ohm input Z) ! Note ! Set Ch. 2 Input Impedance to 50 ohms, not 1M ohm! 1M ohm setting will not allow detector to discharge rapidly, and will give erroneous results to turn-off time measurment, e.g. will indicate excessively long turn-off times. 1. Signal Generator set such that output power of BFP740F LNA is approx. 0 dBm when LNA is powered ON 2. Channel 1 of oscilloscope monitors input power supply voltage to Amplifier (+3.0 volts when ON, ~ 0 volts when OFF) 3. Channel 2 of oscilloscope monitors rectified RF output of Amplifier 4. To make measurement of turn-on time, turn power supply OFF, reset o’scope, setup trigger to trigger on rising edge of Ch.1 5. To make measurement of turn-off time, turn power supply ON, reset o’scope, setup trigger to trigger on falling edge of Ch. 1 Application Note 22/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time a) Turn On Time: Refer to oscilloscope screen-shot below. Upper trace (yellow, Channel 1) is the DC power supply turnon step waveform whereas the lower trace (green, Channel 2) is the rectified RF output signal of the LNA stage. Amplifier turn-on time is aproximately 50 nanoseconds, or 0.05microseconds. Main source of time delay in the LNA turn-on and turn-off events are the R-C time constants formed by (R3 * C4), [(R2+R3) * C3], etc. Charge storage has been minimized in this circuit so as to speed up turn on and turn off times. (Refer to Schematic diagram on page 6). Application Note 23/ 24 Rev. 1.1, 2009-05-11 Application Note No. 170 BFR740L3RH 5 – 6 GHz LNA with <100 nSec Turn-On / Turn-Off Time b) Turn-Off Time: Rectified RF output signal (lower green trace) takes approximately ~ 30 nanoseconds, or ~0.03 microseconds to settle out after power supply is turned off. Note that input impedance of digital oscilloscope which senses RF Detector Diode output is set to 50 ohms, rather than 1 Megaohm, to permit RF Detector Diode to rapidly discharge after Amplifier is turned off. If input impedance of oscilloscope is set to 1 Megaohm, the RF Detector will have to discharge through this 1 Megaohm impedance, giving excessively long results for turn-off times. Application Note 24/ 24 Rev. 1.1, 2009-05-11