1 MHz to 8 GHz, 70 dB Logarithmic Detector/Controller Data Sheet AD8318 FEATURES FUNCTIONAL BLOCK DIAGRAM VPSI ENBL TADJ VPSO Wide bandwidth: 1 MHz to 8 GHz High accuracy: 1.0 dB over 55 dB range (f < 5.8 GHz) TEMP GAIN TEMP SLOPE SENSOR BIAS I V VSET Stability over temperature: 0.5 dB Low noise measurement/controller output (VOUT) I V VOUT Pulse response time: 10 ns/12 ns (fall/rise) DET DET DET DET Integrated temperature sensor CLPF Small footprint LFCSP INHI Power-down feature: <1.5 mW at 5 V INLO Single-supply operation: 5 V at 68 mA CMIP CMOP Fabricated using high speed SiGe process Figure 1. APPLICATIONS RF transmitter PA setpoint control and level monitoring RSSI measurement in base stations, WLAN, WiMAX, and radars GENERAL DESCRIPTION The AD8318 is a demodulating logarithmic amplifier, capable a decreasing linear-in-dB function of the RF input signal of accurately converting an RF input signal to a corresponding amplitude. decibel-scaled output voltage. It employs the progressive The logarithmic slope is nominally 25 mV/dB but can be compression technique over a cascaded amplifier chain, each adjusted by scaling the feedback voltage from VOUT to the stage of which is equipped with a detector cell. The device is VSET interface. The intercept is 20 dBm (referenced to 50 , used in measurement or controller mode. The AD8318 maintains CW input) using the INHI input. These parameters are very accurate log conformance for signals of 1 MHz to 6 GHz and stable against supply and temperature variations. provides useful operation to 8 GHz. The input range is typically The AD8318 is fabricated on a SiGe bipolar IC process and is 60 dB (referenced to 50 ) with error less than 1 dB. The available in a 4 mm 4 mm, 16-lead LFCSP for the operating AD8318 has a 10 ns response time that enables RF burst o o temperature range of 40 C to +85 C. detection to beyond 45 MHz. The device provides unprecedented 2.4 6 logarithmic intercept stability vs. ambient temperature conditions. 2.2 5 A 2 mV/C slope temperature sensor output is also provided for 2.0 4 additional system monitoring. A single supply of 5 V is required. 1.8 3 Current consumption is typically 68 mA. Power consumption 1.6 2 decreases to <1.5 mW when the device is disabled. 1.4 1 The AD8318 can be configured to provide a control voltage 1.2 0 1.0 1 to a VGA, such as a power amplifier or a measurement output, 0.8 2 from Pin VOUT. Because the output can be used for controller 0.6 3 applications, wideband noise is minimal. 0.4 4 In this mode, the setpoint control voltage is applied to VSET. 0.2 5 The feedback loop through an RF amplifier is closed via VOUT, 0 6 65 60 55 50 45 40 35 30 25 20 15 10 5 0 5 10 the output of which regulates the amplifier output to a magnitude P (dBm) IN corresponding to VSET. The AD8318 provides 0 V to 4.9 V Figure 2. Typical Logarithmic Response and Error vs. Input Amplitude at 5.8 GHz output capability at the VOUT pin, suitable for controller applications. As a measurement device, Pin VOUT is externally connected to VSET to produce an output voltage, V which is OUT, Rev. D Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20042017 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com V (V) OUT 04853-001 ERROR (dB) 04853-052AD8318 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Temperature Compensation of Output Voltage ..................... 13 Applications ....................................................................................... 1 Temperature Sensor ................................................................... 14 Functional Block Diagram .............................................................. 1 Measurement Mode ................................................................... 14 General Description ......................................................................... 1 Device Calibration and Error Calculation .............................. 15 Revision History ............................................................................... 2 Selecting Calibration Points to Improve Accuracy over a Reduced Range ........................................................................... 16 Specifications ..................................................................................... 3 Variation in Temperature Drift from Device to Device ........ 17 Absolute Maximum Ratings ............................................................ 6 Temperature Drift at Different Temperatures ........................ 17 ESD Caution .................................................................................. 6 Setting the Output Slope in Measurement Mode .................. 17 Pin Configuration and Function Descriptions ............................. 7 Response Time Capability ......................................................... 18 Typical Performance Characteristics ............................................. 8 Output Filtering .......................................................................... 18 Theory of Operation ...................................................................... 11 Controller Mode ......................................................................... 19 Using the AD8318 .......................................................................... 12 Characterization Setup and Methods ...................................... 21 Basic Connections ...................................................................... 12 Evaluation Board ............................................................................ 22 Enable Interface .......................................................................... 12 Outline Dimensions ....................................................................... 24 Input Signal Coupling ................................................................ 12 Ordering Guide .......................................................................... 24 Output Interface ......................................................................... 13 Setpoint Interface ....................................................................... 13 REVISION HISTORY 12/2017Rev. C to Rev. D Changes to Table 1 ............................................................................. 3 Updated Outline Dimensions ....................................................... 24 Changes to Figure 5, Figure 6, and Figure 7 Captions .................. 8 Changes to Ordering Guide .......................................................... 24 Changes to Figure 12 Caption ......................................................... 9 Changes to Figure 15 Caption ......................................................... 9 8/2017Rev. B to Rev. C Changed General Description Heading to Theory of Change to Figure 3 ........................................................................... 7 Operation ......................................................................................... 11 Updated Outline Dimensions ...................................................... 24 Changes to Enable Interface Section............................................ 12 Changes to Ordering Guide .......................................................... 24 Inserted Figure 24 ........................................................................... 12 Changes to Input Signal Coupling Section ................................. 12 4/2007Rev. A to Rev. B Changes to Measurement Mode Section ..................................... 14 Added Figure 2 Renumbered Sequentially .................................. 1 Changes to Figure 36 ...................................................................... 17 Changes to Table 1 ............................................................................ 3 Added Output Filtering Section ................................................... 19 Changes to Figure 23 ...................................................................... 12 Changes to Controller Mode Section .......................................... 19 Changes to Characterization Setup and Methods Section ........ 21 Changes to Response Time Capability Section .......................... 18 Changes to Figure 48 ...................................................................... 23 Changes to Table 6 .......................................................................... 22 Updated Outline Dimensions ....................................................... 24 Changes to Figure 47, Figure 48, and Figure 49 ......................... 23 Changes to Ordering Guide .......................................................... 24 Updated Outline Dimensions ....................................................... 24 Changes to Ordering Guide .......................................................... 24 1/2006Rev. 0 to Rev. A Changed TADJ Resistor to R Resistor ........................ Universal 7/2004Rev. 0: Initial Version TADJ Changes to Applications .................................................................. 1 Rev. D Page 2 of 24