1 Features
• Ultra-fast transient response to low current levels:
– Settling time for 10‑nA to 100‑nA step:
220‑ns rising, 630‑ns falling (typ)
– Settling time for 100‑nA to 1‑μA step:
80‑ns rising, 240‑ns falling (typ)
• Wide dynamic current range:
100 pA to 10 mA (160 dB)
• High signal bandwidth:
– 6 MHz at 1 μA to 10 mA
– 120 kHz at 1 nA
• High-accuracy transfer function:
– 0.2 % max log conformity error
• Integrated reference current (1 μA) and reference
voltages (2.5 V and 1.65 V) for accurate ratio
calculation
• Low reference drift: 20 ppm/°C (typ)
• Additional auxiliary high-speed op amp for
differential ADC drive, single-ended gain or filter
blocks, and other peripheral functions
• Single supply (4.5 V to 12.6 V) or
dual supply (±2.25 V to ±6.3 V) operation
• Low quiescent current: 9.5 mA
• Specified temperature range: –40°C to +125°C
• Small package: 3 mm × 3 mm VQFN

2 Applications
• Optical modules
• Inter-DC interconnect
• Optical network terminal unit
• Chemistry/gas analyzer
• Erbium-doped fiber optic amplifier (EDFA)

3 Description
The LOG200 is a wide-dynamic-range current-tovoltage
amplifier specifically designed to optimize
current measurements across 160 dB of dynamic
range with unparalleled accuracy and speed
for optical communications, medical diagnostics,
and industrial process control measurements. The
LOG200 features two logarithmic amplifiers followed
by a high-accuracy differential amplifier that convert
current signals into a voltage representing the logcompressed
ratio of the two currents. The current
inputs are designed to feature a high-speed response
from one input, and a highly accurate reference
signal on the other input, allowing for a unique
combination of fast transient response and high
logarithmic conformity.
The LOG200 ratio is internally set to 250 mV/
decade of current-to-voltage conversion. The device
integrates an uncommitted high-speed amplifier to
allow the output to be configured for differential or
filtered responses, with a fast settling time to drive
successive approximation analog-to-digital converters
(SAR ADCs). The LOG200 also features a separate
reference current and reference voltage designed to
configure the device for optimized input current and
common-mode voltages.
The LOG200 can be powered in a single-supply
(4.5 V to 12.6 V) or dual-supply (±2.25 V to ±6.3 V)
configuration and is specified from –40°C to +125°C.