LTC5596 datasheet(20/22 Pages) AD

20 / 22 page

LTC5597

Rev. 0

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APPLICATIONS INFORMATION

The LOG-linearity error curves in the Typical Performance

Characteristics section were obtained using linear

regression, applied to the response of the individual

detector devices at T = 25°C. For all frequencies, the

input power range from –37dBm to –5dBm was used. The

resulting LOG-linearity error tends to have larger negative

values than positive values. To center the error curves

within the ±1dB range, an additional 0.5dB was added

to the PINTERCEPT parameter. This slightly increases the

measurement error at T = 25°C, but results in a smaller

error over the full temperature range. The calculated

LOG-slope and LOG-intercept numbers are displayed in

the tables on page 4 and 5.

A better measurement accuracy is achieved if the inter-

preter uses the actual detector response at T = 25°C as

model for the detector, instead of the perfect linear-in-dB

response described above. The resulting measurement

error, the temperature drift error, equals:

TemperatureDriftError=[VOUT(T)–VOUT(25°C)]/SLOPE

A system that achieves this measurement error should

store the full output voltage vs input power response of

the detector with suitable resolution. The error curves

displayed on page 9 and 10 represent the achieved power

measurement accuracy using this configuration.

LTC5596 Datasheet(PDF) 20 Page - Analog Devices