LTC5509

6

5509f

APPLICATIO S I FOR ATIO

Operation

The LTC5509 RF detector integrates several functions to

provide RF power detection over frequencies ranging from

300MHz to 3GHz. These functions include an internally

compensated buffer amplifier, an RF Schottky diode peak

detector and level shift amplifier to convert the RF feedback

signal to DC and a delay circuit to avoid voltage transients

not incorporate gain compression. Consequently, it offers

a linear transfer relationship between RF input voltage and

DC output voltage.

Buffer Amplifier

The buffer amplifier is capable of driving a 2mA load. The

buffer amplifier typically has an output voltage range of

maximum output swing is reduced.

RF Detector

The internal RF Schottky diode peak detector and level

shift amplifier converts the RF input signal to a low

frequency signal. The detector demonstrates excellent

efficiency and linearity over a wide range of input power.

The Schottky detector is biased at about 60

µA and drives

a peak detector capacitor of 28pF.

Modes of Operation

MODE

SHDN

OPERATION

Shutdown

Low

Disabled

Enable

High

Power Detect

Applications

The LTC5509 can be used as a self-standing signal strength

measuring receiver for a wide range of input signals from

–30dBm to 6dBm for frequencies from 300MHz to 3GHz.

The LTC5509 can be used as a demodulator for AM and

ASK modulated signals with data rates up to 1.5MHz.

Depending on specific application needs, the RSSI output

can be split into two branches, providing AC-coupled data

(or audio) output and DC-coupled, RSSI output for signal

strength measurements and AGC.

The LTC5509 can be used for RF power detection and

control. Refer to Application Note 91, “Low Cost Coupling

Methods for RF Power Detectors Replace Directional

Couplers.”

Demo Board Schematic

SHDN

GND

RF

GND

LTC5509

1

2

3

JP1

R2

68

Ω

(OPT)

R1

68

Ω

(OPT)

C5

(OPT)

C2

0.1

µF

C3

100pF

C1

33pF

J1

E1

E5

E2

E4

E3

GND

GND

SHDN

R3

22k

ENABLE

DISABLE

5509 AI01