Log detectors and RMS detectors are core amplitude detection devices in the RF/microwave field, with three key differences:
- Detection Principle: Log detectors utilize the nonlinear volt-ampere characteristics of diodes to convert the logarithm of signal amplitude into a DC voltage. RMS detectors, based on the principle of energy equivalence, calculate the Root Mean Square (RMS) value of the signal and convert it into a DC voltage.
- Output Characteristics: The output of a log detector exhibits a linear-logarithmic relationship, featuring a wide dynamic range and fast response but low accuracy, and it is sensitive to waveforms. The output of an RMS detector shows a linear-energy relationship, with a narrow dynamic range and slow response but high accuracy, and it is insensitive to waveforms.
- Applicable Scenarios: Log detectors are used for RF signal strength monitoring, receiver Automatic Gain Control (AGC), interference signal monitoring, and peak power monitoring. RMS detectors are applied in audio signal amplitude measurement, RF power meters, communication system bit error rate testing, and non-sinusoidal signal measurement.