CN-0178 Datasheet, PDF (4/5 Pages) Analog Devices – Software-Calibrated, 50 MHz to 9 GHz, RF Power Measurement System

CN-0178
Circuit Note
COMMON VARIATIONS
For applications that require less RF detection range, the
AD8363 rms detector can be used. The AD8363 has a detection
range of 50 dB and operates at frequencies up to 6 GHz. For
non-rms detection applications, the AD8317/AD8318/AD8319
or ADL5513 can be used. These devices offer varying detection
ranges and have varying input frequency ranges up to 10 GHz
(see CN-0150 for more details).
The AD7466 is a single channel, 12-bit ADC with SPI interface.
If the end application requires a multichannel ADC, the dual
12-bit AD7887 can be used. In multichannel applications that
require multiple ADC and DAC channels, the AD7294 can be
used. In addition to providing four 12-bit DAC outputs, this
subsystem chip includes four uncommitted ADC channels,
two high-side current sense inputs, and three temperature
sensors. Current and temperature measurements are digitally
converted and available to read over the I²C-compatible
interface.
CIRCUIT EVALUATION AND TEST
This circuit uses the EVAL-CN0178-SDPZ circuit board and
the EVAL-SDP-CB1Z System Demonstration Platform (SDP)
evaluation board. The two boards have 120-pin mating
connectors, allowing for the quick setup and evaluation of the
circuit’s performance. The EVAL-CN0178-SDPZ board contains
the circuit to be evaluated, as described in this note, and the
SDP evaluation board is used with the CN0178 evaluation
software to capture the data from the EVAL-CN0178-SDPZ
circuit board.
Equipment Needed
• PC with a USB port and Windows® XP or Windows Vista®
(32-bit), or Windows® 7 (32-bit)
• EVAL-CN0178-SDPZ Circuit Evaluation Board
• EVAL-SDP-CB1Z SDP Evaluation Board
• CN0178 Evaluation Software
• Power supply: +6 V, or +6 V “wall wart”
• Environmental chamber
• RF signal source
• Coaxial RF cable with SMA connectors
Getting Started
Load the evaluation software by placing the CN0178 Evaluation
Software disc in the CD drive of the PC. Using "My Computer,"
locate the drive that contains the evaluation software disc and
open the Readme file. Follow the instructions contained in the
Readme file for installing and using the evaluation software.
Functional Block Diagram
See Figure 1 of this circuit note for the circuit block diagram,
and the file “EVAL-CN0178-SDPZ-SCH-Rev0.pdf ” for the
circuit schematics. This file is contained in the CN0178 Design
Support Package.
Setup
Connect the 120-pin connector on the EVAL-CN0178-SDPZ
circuit board to the connector marked “CON A” on the
EVAL-SDP-CB1Z evaluation (SDP) board. Nylon hardware
should be used to firmly secure the two boards, using the holes
provided at the ends of the 120-pin connectors. Using an
appropriate RF cable, connect the RF signal source to the
EVAL-CN0178-SDPZ board via the SMA RF input connector.
With power to the supply off, connect a +6 V power supply to
the pins marked “+6 V” 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. Connect
the USB cable supplied with the SDP board to the USB port on
the PC. Note: Do not connect the USB cable to the mini USB
connector on the SDP board at this time.
Test
Apply power to the +6 V supply (or “wall wart”) connected to
EVAL-CN0178-SDPZ circuit board. Launch the Evaluation
software, and connect the USB cable from the PC to the USB
mini-connector on the SDP board.
Once USB communications are established, the SDP board can
now be used to send, receive, and capture serial data from the
EVAL-CN0178-SDPZ board.
The data in this circuit note were generated using a Rohde &
Schwarz SMT-03 RF signal source, and an Agilent E3631A
power supply. The signal source was set to the frequencies
indicated in the graphs, and the input power was stepped and
data recorded in 1 dB increments.
Temperature testing was performed using a Test Equity Model
107 environmental chamber. The CN0178-SDPZ evaluation
board was placed in the chamber via a slot in the test chamber
door, with the SDP evaluation board extending outside.
Information and details regarding how to use the evaluation
software for data capture can be found in the CN0178
Evaluation Software ReadMe file.
Information regarding the SDP board can be found in the
SDP User Guide.
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