The ADL5304ACPZ-R7 is a high speed Logarithmic Converter with fast response and low noise over a 200dB (1pA to 10mA) measurement range. The ADL5304 provides a nominal logarithmic slope of 10mV/dB (200mV/decade), other values are easily configured. Logarithmic intercept can be programmed over a wide range with the internal 100nA current source or externally for log ratio applications. The default intercept value of 3.162fA places the midpoint of the measurement range of 100nA at VLOG=1.5V. A single positive supply of 5V is all that is required for operation over a specified 1pA to 3mA input range. Dual-supply operation extends the specified input current range to 10mA. The ADL5304 accepts two current inputs to the logarithmic argument. The numerator input, INUM, flows in the collector of an NPN transistor, connected in a feedback path around a low offset JFET amplifier. The denominator current, IDEN, is treated in the same way, which allows for log ratio operation.
● Optimized for very fast response at all input currents
● Log ratio or fixed-intercept operation
● Precision voltage references and reference current
● Adaptive photodiode (PD) bias for low dark current
● Programmable log slope and intercept
● Default log slope of 10 mV/dB at VLOG pin
● ±0.25dB from 100pA to 100µA Law conformance
