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This version (21 Dec 2017 03:21) was approved by trishacabildo.

CN0178 Evaluation Board Guide

Overview

CN0178 is a circuit that measures the rms signal strength of RF signals with varying crest factors (peak-to-average ratio) over a dynamic range of approximately 65 dB and operates at frequencies from 50 MHz up to 9 GHz using the ADL5902 TruPwr™ detector. The measurement result is provided as serial data at the output of a 12-bit ADC. A simple 4-point system calibration at ambient temperature is performed in the digital domain.

The ADL5902 provides a solution in a variety of high frequency systems requiring an accurate measurement of signal power. It can operate from 50 MHz to 9 GHz and can accept inputs from −62 dBm to at least +3 dBm with large crest factors, such as GSM, CDMA, W-CDMA, TD-SCDMA, WiMAX, and LTE modulated signals.

The AD7466 12-bit, high speed, low power, successive approximation analog-to-digital converters (ADC). It operates from a single 1.6 V to 3.6 V power supply and feature throughput rates up to 200 kSPS with low power dissipation. The parts contain a low noise, wide bandwidth track-and-hold amplifier, which can handle input frequencies in excess of 3 MHz.

The EVAL-CN0178-SDPZ board connects to ADI’s System Demonstration Platform (SDP) and is powered by a +6 V supply or +6 V “wall wart”.


Required Equipment

  • EVAL-SDP-CB1Z Controller Board (SDP-B Board)
  • 6 V or 6 V Wall wart
    • Agilent E3631A power supply
  • PC with the following Minimum Requirements
    • Windows 7 (32-bit), Windows Vista (32-bit) or Windows XP
    • USB interface
  • RF signal source
    • Rohde & Schwarz SMT-03 RF signal source
  • Coaxial RF cable with SMA connectors

General Setup

Block assignments


  • The EVAL-CN0178-SDPZ (CN-0178 Board) connects to the EVAL-SDP-CB1Z (SDP-B Board) via the 120-Pin connector
  • The EVAL-SDP-CB1Z (SDP-B Board) connects to the PC via the USB cable.
  • Terminal block J1 is the +6 V power supply
  • Terminal block J2 is the +6 V barrel connector for wall wart supply input
  • Terminal block J3 is the SMA connector for RF input


Test setup


  1. Connect the 120-pin connector on the EVAL-CN0178-SDPZ Evaluation Board to the connector marked “CON A” on the EVAL-SDP-CB1Z evaluation (SDP) board
  2. Connect the RF signal source to the EVAL-CN0178-SDPZ Evaluation Board via the SMA RF input connector
  3. With power to the supply off, connect a +6 V power supply to the pins marked “+6V” and “GND” on the board
    • If available, a +6 V “wall wart” can be connected to the barrel connector on the board and used in place of the +6 V power supply
  4. Connect the USB cable supplied with the SDP board to the USB port on the PC
  5. Apply power to the +6 V supply (or “wall wart”) connected to EVAL-CN0178-SDPZ Evaluation Board
  6. Launch the evaluation software
  7. Connect the USB cable from the PC to the USB mini connector on the SDP board


Do not connect the USB cable to the Mini-USB connector on the SDP board before turning on the dc power supply for the EVAL-CN0178-SDPZ.


Calibration

Because the slope and intercept of the system vary from device to device, a system level calibration is required. For this board, a 4-point calibration is used to correct for some non-linearity in the RF detector's transfer function particularly at the low end.

  1. Apply four known signal levels to ADL5902. Note that it should be well within the linear operating range of the device
  2. Measure the corresponding output codes from the ADC
  3. Calculate SLOPE_ADC and INTERCEPT calibration coefficients using the following equations:
    • SLOPE_1 = (CODE_1 - CODE_2)/(PIN_1 - PIN_2)
    • INTERCEPT1 = CODE_1/(SLOPE_ADC/PIN_1)
  4. This calculation is repeated using CODE2/CODE3 and CODE3/CODE4 to calculate SLOPE2/INTERCEPT2 and SLOPE3/INTERCEPT3 respectively
  5. These will be used to calculate the unknown input power level, PIN, when operation in the field using the equation
    • PIN = (CODE/SLOPE) + INTERCEPT
  6. The observed code from the ADC will be compared to the calibration coefficient codes in order to retrieve the appropriate SLOPE and INTERCEPT calibration coefficients.
    • Example: If CODE from ADC is between CODE1 and CODE2, then SLOPE1/INTERCEPT1 should be used



Installing the Evaluation Software

  1. Extract the file CN0178_Evaluation_Software.zip and open the file setup.exe.

    NOTE: It is recommended that you install the CN0178 Evaluation Software to the default directory path C:\Program Files (x86)\Analog Devices\CN0178\ and all National Instruments products to C:\Program Files\National Instruments\

  2. Click Next to view the installation review page



  3. Click Next to start the installation



  4. Upon completion of the installation of the CN-0178 Evaluation Software, the installer for the ADI SDP Drivers will execute.

    NOTE: It is recommended that you close all other applications before clicking “Next”. This will make it possible to update relevant system files without having to reboot your computer.





  5. Press “Next” to set the installation location for the SDP Drivers.

    It is recommended that you install the drivers to the default directory path
    C:\Program Files\Analog Devices\SDP\Drivers





  6. Press “Install” to install the SDP Drivers and complete the installation of all software. Click “Finish” when done.


Using the Evaluation Software

Main Window

  1. Connect Button - Starts the connection between the CN0178 Evaluation Board and SDP-B Controller Board.
  2. Disconnect Button - Ends the connection between the CN0178 Evaluation Board and SDP-B Controller Board
  3. SDP Connector - Selects which 120-pin connection of the SDP-B Board to use
  4. Input Power - Indicate input signal power level
  5. Frequency - Indicate input signal frequency
  6. Data Acquisition Controls
    • Sample Data - Start acquisition of measurement data
    • Remove Data Point - Remove a data point from samples
    • Clear Data - Clear the current measurement data
    • Save Data - Save measurement data to file
  7. Sample Data Graph Tab - Shows the XY plot of ADC code and output error (%) with respect to the shunt voltage
    • Plot Options - Edit plot display and options like interpolation and color of output waveform
  8. Calibration Tab
    • Calibration Inputs - Four point input power levels used for calibration purposes
    • Calibration Data - Enable calibration of the device
    • Calibration Coefficients - Read only. Calculated calibration coefficients based on four point input power levels
  9. Administration Tab
    • Read Firmware - Reads the firmware of CN0150 Evaluation Board
    • Flash LED - Flashes the LED on the SDP controller board
  10. Quit Button - Closes the evaluation software


Running the System

  1. Open the CN0178.exe application from the default installation location
  2. Set the correct connector and click the Connect Button
  3. Upon successful connection, calibrate the device through the calibration tab
  4. After proper calibration, set the correct input parameters and control the data measurement through the data acquisition control buttons
  5. Click Disconnect if finished
  6. Click Quit to exit the program



Schematic, PCB Layout, Bill of Materials

EVAL-CN0178-SDPZ Design & Integration Files

  • Schematics
  • PCB Layout
  • Bill of Materials
  • PADS project

End of Document

resources/eval/user-guides/circuits-from-the-lab/cn0178.txt · Last modified: 04 Dec 2017 10:38 by trishacabildo