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Table of Contents

CN0150 Evaluation Board Guide

Overview

CN0150 is a circuit that measures RF power at any frequency from 1 MHz to 8 GHz over a range of approximately 60 dB. The measurement result is provided as a digital code at the output of a 12-bit ADC with serial interface and integrated reference. The output of the RF detector has a glueless interface to the ADC and uses most of the ADC’s input range without further adjustment. A simple two-point system calibration is performed in the digital domain.

The AD8318 is a demodulating logarithmic amplifier, capable of accurately converting an RF input signal to a corresponding decibel-scaled output voltage. It employs the progressive compression technique over a cascaded amplifier chain, each stage of which is equipped with a detector cell. It maintains accurate log conformance for signals of 1 MHz to 6 GHz and provides useful operation to 8 GHz. The input range is typically 60 dB (re: 50 Ω) with error less than ±1 dB and provides a typical output voltage temperature stability of ±0.5 dB.

The AD7887 is a high speed, low power, 12-bit analog-to-digital converter (ADC) that operates from a single 2.7 V to 5.25 V power supply. It is capable of 125 kSPS throughput rate. The output coding for the AD7887 is straight binary, and the part is capable of converting full power signals of up to 2.5 MHz. The ADC can be configured for either dual or single channel operation via the on-chip control register. There is a default single-channel mode that allows the AD7887 to be operated as a read-only ADC, thereby simplifying the control logic.

The EVAL-CN0150-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

General Setup

Block assignments


  • The EVAL-CN0150-SDPZ (CN-0150 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-CN0150A-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-CN0150A-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-CN0150A-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-CN0150-SDPZ.


Calibration

Because the slope and intercept of the system vary from device to device, a system level calibration is required.

  1. Apply two known signal levels PIN_1 and PIN_2 close to the endpoints of the AD8318 linear input range. Note that it should be well within the linear operating range of the device (-50 dBm to -10 dBm for this device)
  2. Measure the corresponding output codes CODE_1 and CODE_2 from the ADC
  3. Calculate SLOPE_ADC and INTERCEPT using the following equations:
    • SLOPE_ADC = (CODE_2 - CODE_1)/(PIN_2 - PIN1)
    • INTERCEPT = PIN_2 - (CODE_2/SLOPE_ADC)
  4. These will be used to calculate the unknown input power level, PIN, when operation in the field using the equation
    • PIN = (CODE_OUT/SLOPE_ADC) + INTERCEPT


Installing the Evaluation Software

  1. Extract the file CN0150_Evaluation_Software.zip and open the file setup.exe.

    NOTE: It is recommended that you install the CN0150 Evaluation Software to the default directory path C:\Program Files (x86)\Analog Devices\CN0150\ and all National Instruments products to C:\Program Files\National Instruments\

  2. Accept the license agreement to proceed to the installation review page

    }

  3. Click Next to view the installation review page



  4. Click Next to start the installation



  5. Upon completion of the installation of the CN-0150 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.





  6. 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





  7. 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 CN0150 Evaluation Board and SDP-B Controller Board.
  2. Reset and Disconnect Button - Resets and ends the connection between the CN0150 Evaluation Board and SDP-B Controller Board
  3. Sample Data Graph Tab - Shows the XY plot of ADC code and output error (%) versus input signal power. Also contains the plot options where you can edit plot display and options like interpolation and color of output waveform
  4. Test Setup Tab
    • Data Acquisition
      • Input Power - Indicate input signal power level
      • Frequency - Indicate input signal frequency
      • Temperature - Temperature test level condition of the input signal
      • Acquire Data - Start acquisition of measurement data
      • Clear Data - Clear the current measurement data
      • Save Data to File - Save measurement data to file
      • Increment Amount
      • Average Value
      • Sample size
      • Remove Last
      • Auto-increment
    • Calibration - insert calibration instructions here
      • PIN_1 - First known input power level close to endpoints of AD8318 linear input range
      • PIN_2 - Second known input power level close to endpoints of AD8318 linear input range
      • Slope (ADC Code/ dBm) - Slope of the transfer curve of AD8318 (-24 mV/dB nominal)
      • Intercept (ADC Code) - X-axis intercept with a unit of dBm
  5. Configure Tab
    • SDP Connector - Selects which 120-pin connection of the SDP-B Board to use
    • SCLK Frequency - Sets the SPI clock frequency for the data transfers used by the evaluation board
    • AD7887 Voltage Reference - Select between internal or external 2.5 volts voltage reference
    • SPI Byte to Write - Buffer of unsigned 16-bit elements for SPI write transfer
    • Flash LED - Flashes the LED on the SDP controller board
    • Read Firmware - Reads the firmware of CN0150 Evaluation Board


—-

Schematic, PCB Layout, Bill of Materials

EVAL-CN0150-SDPZ Design & Integration Files

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

End of Document

resources/eval/user-guides/circuits-from-the-lab/cn0150.1511925614.txt.gz · Last modified: 29 Nov 2017 04:20 by Trisha Cabildo

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