LT5504

1

5504f

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

■

RF Frequency Range: 800MHz to 2.7GHz

■

Low Supply Current: 14.7mA at 3V

800MHz to 2.7GHz

RF Measuring Receiver

The LT

grated measuring receiver, capable of detecting a wide

dynamic range RF signal from –75dBm to +5dBm. The

logarithm of the RF signal is precisely converted into a

linear DC voltage. The LT5504 consists of RF/IF limiters,

an LO buffer amplifier, a limiting mixer, a 3rd-order

450MHz integrated low pass filter, RF/IF detectors and an

output interface. The ultrawide dynamic range is achieved

by simultaneously measuring the RF signal and a down-

converted IF signal obtained using the on-chip mixer and

an external local oscillator. The RF- and IF-detected sig-

nals are summed to generate an accurate linear DC voltage

proportional to the input RF voltage (or power) in dB. The

output is buffered with a low output impedance driver.

, LTC and LT are registered trademarks of Linear Technology Corporation.

5504 TA01a

• • •

RF+

RF–

R1

82Ω

RF

INPUT

ENABLE

GND

LO

LO

INPUT

OUTPUT

C3

10pF

C1

100pF

R2

200Ω

EN

3V

C2

1nF

LT5504

RF

DETECTOR

IF

DETECTOR

IF

DETECTOR

Output Voltage and Slope

Variation vs RF Input Power

PIN (dBm)

–80

2.4

2.0

1.6

1.2

0.8

0.4

0

–60

–40 –30

10

5504 TA01b

–70

–50

–20 –10

0

6

4

2

0

–2

–4

–6

AVERAGE SLOPE:23mV/dB