AD8313 RF signal-strength meter

How it works

The AD8313 logarithmic detector converts RF amplitude into a DC output. The LM3914 uses that voltage to drive a ten-LED display, giving a convenient relative indication of signal strength.

The original description mentions 10 dB steps. Calibrating those steps requires a known RF level at the frequency of interest; an antenna connection alone does not create an absolute power measurement.

On the bench

Place the specified surface-mount bypass components close to the AD8313. Use appropriate RF layout and input-level protection, and distinguish a dB change from an absolute level in dBm.

Resources & provenance

Rewritten from the original circuits/msr/r3j19ns_msr008.php page. Component values and historical performance claims have not been independently bench-tested. The circuit figures have had their watermarks removed.