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LOG200

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High-speed precision logarithmic amplifier with photodiode bias and dark-current correction

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Data sheet

LOG200

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Product details

Input current range (min) (nA) 0.1 Input current range (max) (mA) 10 Offset voltage (input amplifiers) (max) (mV) 2000 Vs (±) (min) (V) 4.5 Vs (±) (max) (V) 12.6 Iq (max) (mA) 9 Dynamic range (typ) (dB) 160 Reference type Int Auxiliary op amps 1 Full-scale output voltage (min) (±V) 4.8 Full-scale output voltage (max) (±V) 12.3 Conformity error (initial 5 decades) (max) (%) 1.5 Conformity error (initial 5 decades) (typ. over temp) (%/°C) 0.2 Operating temperature range (°C) -40 to 125 Rating Catalog
Input current range (min) (nA) 0.1 Input current range (max) (mA) 10 Offset voltage (input amplifiers) (max) (mV) 2000 Vs (±) (min) (V) 4.5 Vs (±) (max) (V) 12.6 Iq (max) (mA) 9 Dynamic range (typ) (dB) 160 Reference type Int Auxiliary op amps 1 Full-scale output voltage (min) (±V) 4.8 Full-scale output voltage (max) (±V) 12.3 Conformity error (initial 5 decades) (max) (%) 1.5 Conformity error (initial 5 decades) (typ. over temp) (%/°C) 0.2 Operating temperature range (°C) -40 to 125 Rating Catalog
VQFN (RGT) 16 9 mm² 3 x 3
  • 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
  • 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

The LOG200 is a wide-dynamic-range current-to-voltage 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 log-compressed 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.

The LOG200 is a wide-dynamic-range current-to-voltage 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 log-compressed 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.
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Technical documentation

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* Data sheet LOG200 Precision, High-Speed Logarithmic Amplifier With Integrated Photodiode Bias datasheet PDF | HTML 14 Aug 2023
EVM User's guide LOG200 Evaluation Module User's Guide (Rev. A) PDF | HTML 22 Jan 2024
Certificate LOG200EVM EU Declaration of Conformity (DoC) 30 Jun 2023

Design & development

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Evaluation board

LOG200EVM — LOG200 evaluation module for high-speed precision logarithmic amplifier with photodiode bias

The LOG200 evaluation module (EVM) is a development platform for evaluating the LOG200, which is a precision, high-speed logarithmic amplifier with integrated photodiode bias and dark-current correction. LOG200 is optimized for current measurements across 160 dB of dynamic range with unparalleled (...)

User guide: PDF | HTML
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Simulation model

LOG200 PSpice Model

SBOMCF1.ZIP (97 KB) - PSpice Model
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Simulation model

LOG200 TINA-TI Reference Design

SBOMCF2.TSC (93 KB) - TINA-TI Reference Design
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Simulation model

LOG200 TINA-TI SPICE Model

SBOMCF0.ZIP (38 KB) - TINA-TI Spice Model
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Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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Simulation tool

TINA-TI — SPICE-based analog simulation program

TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
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