50 MHz to 9 GHz

65 dB TruPwr Detector

Data Sheet

ADL5902

Rev. B

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FEATURES

Accurate rms-to-dc conversion from 50 MHz to 9 GHz

Single-ended input dynamic range of 65 dB

No balun or external input matching required

Waveform and modulation independent, such as

GSM/CDMA/W-CDMA/TD-SCDMA/WiMAX/LTE

Linear-in-decibels output, scaled 53 mV/dB

Transfer function ripple: <±0.1 dB

Temperature stability: <±0.3 dB

All functions temperature and supply stable

Operates from 4.5 V to 5.5 V from −40°C to +125°C

Power-down capability to 1.5 mW

Pin-compatible with the 50 dB dynamic range AD8363

APPLICATIONS

Power amplifier linearization/control loops

Transmitter power controls

Transmitter signal strength indication (TSSI)

RF instrumentation

FUNCTIONAL BLOCK DIAGRAM

X2

X2

BIAS AND POWER-

DOWN CONTROL

1

NC

NC

NC

LINEAR-IN-dB VGA

(NEGATIVE SLOPE)

IDET

26pF

2

3

4

11

10

9

5

6

7

8

16

15

14

13

ADL5902

12

VREF

2.3V

TEMPERATURE

SENSOR

INLO

INHI

VPOS

POS

TEMP

VSET

VOUT

CLPF

COMM

COMM

VTGT

VREF

TADJ/PWDN

G = 5

ITGT

Figure 1.

GENERAL DESCRIPTION

The ADL5902 is a true rms responding power detector that has

a 65 dB measurement range when driven with a single-ended

50 Ω source. This feature makes the ADL5902 frequency

versatile by eliminating the need for a balun or any other form

of external input tuning for operation up to 9 GHz.

The ADL5902 provides a solution in a variety of high frequency

systems requiring an accurate measurement of signal power.

Requiring only a single supply of 5 V and a few capacitors, it is

easy to use and capable of being driven single-ended or with a

balun for differential input drive. The ADL5902 can operate

from 50 MHz to 9 GHz and can accept inputs from −62 dBm to

at least +3 dBm with large crest factors, such as GSM, CDMA,

W-CDMA, TD-SCDMA, WiMAX, and LTE modulated signals.

The ADL5902 can determine the true power of a high

frequency signal having a complex low frequency modulation

envelope or can be used as a simple low frequency rms

voltmeter. Used as a power measurement device, VOUT is

connected to VSET. The output is then proportional to the

logarithm of the rms value of the input. In other words, the reading

is presented directly in decibels and is scaled 1.06 V per decade,

or 53 mV/dB; other slopes are easily arranged. In controller mode,

the voltage applied to VSET determines the power level required at

the input to null the deviation from the set point. The output

buffer can provide high load currents.

The ADL5902 has 1.5 mW power consumption when powered

down by a logic high applied to the PWDN pin. It powers up

within approximately 5 μs to the nominal operating current of

73 mA at 25°C. The ADL5902 is supplied in a 4 mm × 4 mm,

16-lead LFCSP for operation over the wide temperature range

of −40°C to +125°C.

The ADL5902 is also pin-compatible with the AD8363, 50 dB

dynamic range TruPwr™ detector. This feature allows the

designer to create one circuit layout for projects requiring

different dynamic ranges. A fully populated RoHS-compliant

evaluation board is available.