Circuit Note

CN-0518

analog.com

Circuits from the Lab™ circuits from Analog Devices have been designed and built by Analog Devices

engineers. Standard engineering practices have been employed in the design and construction of each circuit,

and their function and performance have been tested and verified in a lab environment at room temperature.

However, you are solely responsible for testing the circuit and determining its suitability and applicability for

your use and application. Accordingly, in no event shall Analog Devices be liable for direct, indirect, special,

incidental, consequential or punitive damages due to any cause whatsoever connected to the use of any

Circuits from the Lab circuits. (Continued on last page)

Rev. 0 | 1 of 8

Circuits from the Lab

® reference designs are engi-

neered and tested for quick and easy system integra-

tion to help solve today’s analog, mixed-signal, and

RF design challenges. For more information and/or

support, visit www.analog.com/CN0518.

Devices Connected/Referenced

HMC376

700 MHz to 1 GHz Low Noise Amplifier

ADG901

0 Hz to 4.5 GHz, 40 dB Off Isolation at 1 GHz, 17 dBm P1dB at 1

GHz SPST Switches

ADL5904

DC to 6 GHz, 45 dB TruPower Detector with Envelope Threshold

Detection

LT8330

Low IQ Boost/SEPIC/Inverting Converter with 1 A, 60 V Switch

ADP150

Ultralow Noise, 150 mA CMOS Linear Regulator

ADM7150

800 mA, Ultra Low Noise/High PSRR LDO

ADM7170

6.5 V, 500 mA, Ultralow Noise, High PSRR, Fast Transient Response

CMOS LDO

LTC6991

TimerBlox: Resettable, Low Frequency Oscillator

USB-Powered, 915 MHz RF Low Noise Amplifier Receiver with Overpower Protection Circuit

EVALUATION AND DESIGN SUPPORT

►

Circuit Evaluation Boards

►

CN0518 Circuit Evaluation Board (EVAL-CN0518-EBZ)

►

Design and Integration Files

►

Schematics, Layout Files, Bill of Materials

CIRCUIT FUNCTIONS AND BENEFITS

The International Telecommunication Union allocates the unli-

censed 915 MHz, industrial, scientific and medical (ISM) radio

frequency band for use in Region 2, geographically consisting

of the Americas, Greenland, and some Eastern Pacific Islands.

Advancements in wireless technologies and standards within the

region have made the band popular for short range, wireless

communication systems.

The 915 MHz ISM band places no restrictions on the application

or duty cycle and common uses include amateur radio, supervisory

control and data acquisition (SCADA), and radio frequency identifi-

cation (RFID) systems.

The circuit shown in Figure 1 is a two-stage RF low noise amplifier

(LNA) optimized for receiver signal chains in the 915 MHz ISM

band. At the center frequency, the circuit results in a forward gain

(S21) of 25 dB and an input return loss (S11) of more than 10

dB. The RF input and output ports are designed with a 50 Ω

impedance match, enabling a direct connection between the circuit

and a standard 50 Ω system.

The board includes a high speed overpower cutoff that protects

sensitive downstream equipment connected to the receiver system.

The receiver system also automatically returns to normal operation

when the RF power level drops within the acceptable range. The

RF inputs and outputs are standard subminiature version A (SMA)

connectors, and the entire design is powered by a single micro-

USB connector.

Figure 1. CN0518 Simplified Block Diagram