How to find the right Logarithmic Amplifiers AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Logarithmic Amplifiers
- Application type
- RF power detection calls for demodulating log amps or log detectors. Photodiode or wide-range DC current measurement calls for baseband logarithmic or 'log ratio' amplifiers. These are different products sharing one name, so check which type you need first.
- Dynamic range
- Compare the dynamic range in dB over which log conformance stays within spec, not the headline range. Usable range is narrower than the marketing range once accuracy limits apply.
- Frequency range
- For RF parts, confirm accurate operation at your carrier frequency. Slope and intercept shift with frequency.
- Slope and intercept stability
- Check the slope (mV/dB) and intercept drift with temperature. Drift directly becomes power or current measurement error.
Brands that matter
- Analog Devices: Leads in RF log detectors such as the AD8307/AD8310/AD8318 families.
- Texas Instruments: Makes the LOG112/LOG114 baseband logarithmic amplifiers, which suit photodiode current measurement.
- Infineon: Offers RF power detectors for wireless applications.
What to avoid
- Using a log detector to measure true power of high crest-factor modulated signals. Use an RMS detector instead.
- Choosing an RF log amp for DC photodiode current, or the reverse.
- Uncalibrated breakout modules when absolute accuracy matters.
Questions
Log detector or RMS detector for RF power?
Log detectors give wide dynamic range and fast response but read differently depending on modulation. RMS detectors read true power regardless of waveform.