ADL5920

Data Sheet

Rev. B | Page 10 of 26

Pin No.

Mnemonic

Description

12

DECL

Internal Decoupling Node. Decouple this pin with a 0.1 µF capacitor to ground. Do not

use the voltage on this pin, nominally 3.2 V, externally to set any bias levels. In dc-coupled

applications where VNEGx is connected to −2.5 V, this pin must be connected directly to

ground.

15

VTGT

RMS Target Voltage. The voltage applied to this pin sets the target RF level at the output

of the internal voltage controlled amplifiers that drive the internal squaring cells of the rms

detectors. The recommended voltage for VTGT is 1 V. Increasing VTGT above 1 V degrades

the rms accuracy of the ADL5920. Reducing VTGT below 1 V can improve the rms

accuracy for signals with high crest factors. The voltage on this pin can be derived from

a resistor divider circuit that is driven by the VREF pin (Pin 19).

19

VREF

Reference Voltage Output. This voltage reference has a nominal value of 2.5 V. This

reference output voltage can set the voltage to the TADJI, TADJS, VTGT, and VOCM pins.

20

TADJI

RMS Detector Temperature Compensation. Use this pin to fine tune the temperature

intercept stability of the rms detectors. The voltage applied to this pin can be derived

from VREF using a simple resistor divider.

25, 26, 31, 32

RFOUT, RFIN

RF Inputs and Outputs. The two RFIN pins are common inputs that must always be

connected to each other. Likewise, the two RFOUT pins must always be connected to

each other. The power of the incident signal on RFIN is measured on the VRMSF pin, and

the power on the incident signal into RFOUT is measured on the VRMSR pin. The ratio of

the incident signals on RFIN and RFOUT is measured on the VDIFF+ and VDIFF− pins.

The RFIN and RFOUT pins are interchangeable, allowing the source signal to drive into

RFOUT with the load connected to RFIN. RFIN and RFOUT are normally ac-coupled to

the source and load. RFIN and RFOUT can be dc-coupled by connecting a −2.5 V supply

to the two VNEGx pins and by connecting the DECL pin to ground.

EPAD

Exposed Pad. Connect the exposed pad to a ground plane with low thermal and

electrical impedance.