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 directional 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.
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
