The LOG114 is specifically designed
for measuring low-level and wide dynamic range currents in communications, lasers,
medical, and industrial systems. The device computes the logarithm or log-ratio of
an input current or voltage relative to a reference current or voltage (logarithmic
transimpedance amplifier).
High
precision is verified over a wide dynamic range of input signals on either bipolar
(±5V) or single (5V) supply. Special temperature drift compensation circuitry is
included on-chip. In log-ratio applications, the signal current can be from a high
impedance source such as a photodiode or resistor in series with a low impedance
voltage source. The reference current is provided by a resistor in series with a
precision internal voltage reference, photo diode, or active current source.
The output signal at
VLOGOUT has a scale factor of 0.375V/decade of input current, which
limits the output so that the output fits within a 5V or 10V range. The output can
be scaled and offset with one of the available additional amplifiers, so the output
matches a wide variety of ADC input ranges. Stable DC performance allows accurate
measurement of low-level signals over a wide temperature range. The LOG114 is
specified over a −5°C to 75°C temperature range and can operate from −40°C to
85°C.
The LOG114 is specifically designed
for measuring low-level and wide dynamic range currents in communications, lasers,
medical, and industrial systems. The device computes the logarithm or log-ratio of
an input current or voltage relative to a reference current or voltage (logarithmic
transimpedance amplifier).
High
precision is verified over a wide dynamic range of input signals on either bipolar
(±5V) or single (5V) supply. Special temperature drift compensation circuitry is
included on-chip. In log-ratio applications, the signal current can be from a high
impedance source such as a photodiode or resistor in series with a low impedance
voltage source. The reference current is provided by a resistor in series with a
precision internal voltage reference, photo diode, or active current source.
The output signal at
VLOGOUT has a scale factor of 0.375V/decade of input current, which
limits the output so that the output fits within a 5V or 10V range. The output can
be scaled and offset with one of the available additional amplifiers, so the output
matches a wide variety of ADC input ranges. Stable DC performance allows accurate
measurement of low-level signals over a wide temperature range. The LOG114 is
specified over a −5°C to 75°C temperature range and can operate from −40°C to
85°C.