ADL5303 View Datasheet(PDF) - Analog Devices

Part Name

Description

MFG CO.

ADL5303

160 dB Range 100 pA to 10 mA Low Cost Logarithmic Converter

Analog Devices 

Data Sheet

For an input of 1 nA, SNSD evaluates to almost 0.5 μV/√Hz;

assuming a 20 kHz bandwidth at this current, the integrated

noise voltage is 70 μV rms. However, this calculation is not

complete. The basic scaling of the VBE is approximately

3 mV/dB; translated to 10 mV/dB, the noise predicted by

Equation 7 must be multiplied by approximately 3.33. The

additive noise effects associated with the reference transistor,

Q2, and the temperature compensation circuitry must also be

included. The final voltage noise spectral density presented at

the VLOG pin varies inversely with IPD, but is not a simple

ADL5303

square root relationship. Figure 10 shows the measured noise

spectral density vs. frequency at the VLOG output, for the same

nine-decade spaced values of IPD.

CHIP ENABLE

Power down the ADL5303 by taking the PWDN pin to a high

logic level. The residual supply current in the disabled mode is

typically 60 μA.

Rev. 0 | Page 11 of 24

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