Q.
We are currently using the AD8361 and are currently going through a redesign. We are looking for less temperature variation and better rms accuracy (i.e. waveform independence or the deviation from CW). What are your recommendations?
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A.
Things have moved on quite a bit since we released the AD8361, which was our first RF rms detector. If you want to stick with a linear-in-volts transfer function and want good rms accuracy, I would make some of these suggestions:
ADL5501: Similar detection range to AD8361 with better rms accuracy and temperature stability. It comes in an SC-70 package which some folks find easier to deal with than some of our newer wafer-level chipscale packages (flip chip).
ADL5500: Similar to the ADL5501 in terms of dynamic range but with slightly worse (still better than AD8361) rms accuracy. This is the detector with the tightest temperature performance available. Though it has low drift across the entire 30 dB range over temperature and process variations, it boast a "sweet spot" of ±0.1 dB error from −40°C to +85°C over an 8.5 dB range with only a simple two-point calibration at room temperature. It comes in a small 1.0 mm x 1.0 mm wafer-level csp package (flip chip).
ADL5504: Similar to the ADL5500 and ADL5501 but rms accuracy that is second to none. 1.2 mm x 0.8 mm wafer-level csp package (flip chip)
ADL5505: A derivative of the ADL5504 with slightly worse rms accuracy but the smallest package on the market. It comes in a tiny 0.8 mm x 0.8 mm wafer-level csp package (flip chip)
ADL5502: Same as ADL5504 core but with a second output that can either track the envelope of the signal or hold the most recent peak. Useful if you wanted to calculate the peak-to-average ratio of a signal, or the peak power. 1.5 mm x 1.5 mm flip chip
ADL5511: Similar to ADL5502 but in a larger package. Has the separate envelope tracking output but no peak-hold. Highest detection range of all the devices listed here (around 40 dB). It comes in a 16-lead, 3.0 mm × 3.0 mm lead frame chipscale package.
