9 kHz to 7 GHz, Bidirectional

RMS and VSWR Detector

Data Sheet

ADL5920

Rev. B

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FEATURES

Wideband matched 9 kHz to 7 GHz operation

Forward and reverse power and return loss measurement

49 dB ±1.0 dB input range with −19 dBm minimum input level,

±1.0 dB at 1 GHz

Linear in dB rms (crest factor insensitive) outputs

Insertion loss: 1.1 dB at 1 GHz and 1.9 dB at 6 GHz

Input and output return loss and VSWR

1 GHz: 22 dB/1.16:1

3 GHz: 14 dB/1.5:1

6 GHz: 12 dB/1.7:1

Output IP3: 70.5 dBm at 1 GHz

Directivity

20 dB at 1 GHz

13 dB at 3 GHz

5 dB at 6 GHz

Maximum input power

30 dBm for open or shorted termination

33 dBm for matched termination

APPLICATIONS

Industrial metering

Broadband inline power and return loss measurement

Transmit power control and automatic level control in

wireless transmitters, signal generators, network

analyzers, and wireless communications testers

Condition based monitoring of system modules, cables, and

connectors

FUNCTIONAL BLOCK DIAGRAM

REVERSE

PATH

RMS

DETECTOR

TEMPERATURE

SENSOR

FORWARD

PATH

RMS

DETECTOR

BIDIRECTIONAL BRIDGE

VTEMP

VRMSR

CRMSR

CHPR–

CHPR+

VNEG1

RFIN

PWDN/

TADJS

TADJI

VTGT

VREF

VOCM

DECL

VRMSF

CRMSF

CHPF–

CHPF+

VNEG2

RFOUT

25

28

1

24

27

29

30

21

23

22

16

12

19

15

20

5

10

18

32

3

2

26

31

4

9

6

7

ADL5920

11

17

813

14

VREF

2.5V

Figure 1.

GENERAL DESCRIPTION

The ADL5920 is an ultrawideband, bidirectional detector that

simultaneously measures forward and reverse rms power levels

in a signal path, along with the return loss.

The forward and reverse power traveling through the

integrated bidirectional bridge is measured using two 50 dB

linear in dB rms detectors. The detector output voltages,

available at the VRMSF and VRMSR pins, are proportional to

the forward and reflected power in dBm. A third, differential,

output produces a voltage proportional to the return loss

(reflection coefficient) in dB, closely related to the voltage

standing wave ratio (VSWR). The common-mode level of this

output is externally adjustable through the VOCM pin.

The primary transmission line of the bidirectional bridge, from

RFIN to RFOUT (or vice versa) is dc-coupled and allows small

amounts of dc bias current through the bridge. When dc-coupled

to source and load, the positive and negative supply pins of the

ADL5920 must be connected to +5 V and −2.5 V, respectively

(relative to the dc voltage at RFIN and RFOUT). The internal

detector circuitry is also dc-coupled to the bidirectional bridge

to support measurements down to 9 kHz.

The maximum input signal on each of the RF ports (RFIN and

RFOOUT) is 30 dBm for open and shorted terminations and

33 dBm for a matched termination.

The ADL5920 draws 160 mA from a 5 V supply and has a low

power, power-down mode controlled through the

PWDN/TADJS pin.

The device is supplied in a 32-lead, 5 mm × 5 mm LFCSP and is

specified for ambient operating temperatures in the −40°C to

+85°C range.

Multifunction pin names may be referenced by their relevant

function only.