ADL5304ACPZ-R2 datasheet(24/32 Pages) AD

Part #	ADL5304ACPZ-R2

Description	High Speed, 200 dB Range, Logarithmic Converter

PDF	32 Pages

Scroll/Zoom	100%

Manufacturer	AD [Analog Devices]

Direct Link	http://www.analog.com

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24 / 32 page

ADL5304

Data Sheet

Rev. A | Page 24 of 32

Log Ratio Operation

Because the ADL5304 has two equal inputs, INUM and IDEN, log

ratio operation is possible. The only difference between INUM

and IDEN is that the IMON current derives from the INUM signal and

allows adaptive photodiode bias at this input only. Assuming

that the ratio INUM/IDEN can, in general, be either greater or less

than unity, VLOG can be of either polarity, requiring a negative

supply in some cases. The value of VLOG depends on the

minimum ratio and the slope chosen for the application.

For example, if the ratio can vary from 1:1000 to 1000:1 and a slope

of 20 mV/dB is required, the peak swing is ±1.2 V around VOFS.

Option 5 in Table 4 provides this with an intercept IZ of 17.8 pA

(VOFS = 1.5 V) with VLOG = ±1.2 V around VOFS = 1.5 V, which

results in 0.3 V ≤ VLOG ≤ 2.7 V.

ADL5304ACPZ-R2 Datasheet(PDF) 24 Page - Analog Devices