something of AD637BR

The AD637BR is a complete high accuracy monolithic rms-to-dc
converter that computes the true rms value of any complex
waveform. It offers performance that is unprecedented in integrated
circuit rms-to-dc converters and comparable to discrete
and modular techniques in accuracy, bandwidth and dynamic
range. A crest factor compensation scheme in the AD637BR permits
measurements of signals with crest factors of up to 10 with
less than 1% additional error. The circuit’s wide bandwidth permits
the measurement of signals up to 600 kHz with inputs of
200 mV rms and up to 8 MHz when the input levels are above
1 V rms.
As with previous monolithic rms converters from Analog Devices,
the AD637BR has an auxiliary dB output available to the user. The
logarithm of the rms output signal is brought out to a separate
pin allowing direct dB measurement with a useful range of
60 dB. An externally programmed reference current allows the
user to select the 0 dB reference voltage to correspond to any
level between 0.1 V and 2.0 V rms.