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LOG114

ACTIVE

Precision High-Speed Logarithmic Amplifier with 2.5V Reference and Uncommitted Output Op Amps

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LOG200 ACTIVE High-speed precision logarithmic amplifier with photodiode bias and dark-current correction Upgraded performance with smaller package option

LOG114

ACTIVE
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Product details

Scale factor (V/decade) 0.375 Input current range (min) (nA) 0.1 Input current range (max) (mA) 10 Offset voltage (input amplifiers) (max) (mV) 4 Vs (±) (min) (V) 4.8 Vs (±) (max) (V) 11 Iq (max) (mA) 15 Dynamic range (typ) (dB) 160 Reference type Internal Auxiliary op amps 2 Full-scale output voltage (min) (±V) -4.4 Full-scale output voltage (max) (±V) 4.4 Conformity error (initial 5 decades) (max) (%) 0.2 Conformity error (initial 5 decades) (typ. over temp) (%/°C) 0.1 Operating temperature range (°C) 0 to 70 Specified voltage (±V) 5 Rating Catalog
Scale factor (V/decade) 0.375 Input current range (min) (nA) 0.1 Input current range (max) (mA) 10 Offset voltage (input amplifiers) (max) (mV) 4 Vs (±) (min) (V) 4.8 Vs (±) (max) (V) 11 Iq (max) (mA) 15 Dynamic range (typ) (dB) 160 Reference type Internal Auxiliary op amps 2 Full-scale output voltage (min) (±V) -4.4 Full-scale output voltage (max) (±V) 4.4 Conformity error (initial 5 decades) (max) (%) 0.2 Conformity error (initial 5 decades) (typ. over temp) (%/°C) 0.1 Operating temperature range (°C) 0 to 70 Specified voltage (±V) 5 Rating Catalog
VQFN (RGV) 16 16 mm² (4 mm × 4 mm)
  • Advantages:
    • Tiny for high density systems
    • Precision on one supply
    • Fast over eight decades
    • Fully-tested function
  • Two scaling amplifiers
  • Wide input dynamic range: eight decades, 100pA to 10mA
  • 2.5V reference
  • Stable over temperature
  • Low quiescent current: 10mA
  • Dual or single supply: ±5V, 5V
  • Package: Small QFN-16 (4mm × 4mm)
  • Specified temperature range: −5°C to 75°C
  • Advantages:
    • Tiny for high density systems
    • Precision on one supply
    • Fast over eight decades
    • Fully-tested function
  • Two scaling amplifiers
  • Wide input dynamic range: eight decades, 100pA to 10mA
  • 2.5V reference
  • Stable over temperature
  • Low quiescent current: 10mA
  • Dual or single supply: ±5V, 5V
  • Package: Small QFN-16 (4mm × 4mm)
  • Specified temperature range: −5°C to 75°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.

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.
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* Data sheet LOG114 Single-Supply, High-Speed, Precision Logarithmic Amplifier datasheet (Rev. C) PDF | HTML Dec 10, 2025

Design & development

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Evaluation board

LOG114EVM — LOG114 Evaluation Module

The LOG114EVM is a ready-to-use platform for evaluating the performance of the LOG114 in various configurations.The LOG114EVM comes configured to operate on a single 5-V power supply. The circuit used in the LOG114EVM is designed to operate over a wide range of input currents (10 nA to 10 mA) and (...)

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Simulation model

LOG114 PSpice Model (Rev. C)

SBOM383C.ZIP (53 KB) - PSpice model
Supported products & hardware
Simulation model

LOG114 TINA-TI Reference Design (Rev. C)

SBOM384C.TSC (101 KB) - TINA-TI reference design
Supported products & hardware
Simulation model

LOG114 TINA-TI Spice Model (Rev. C)

SBOM385C.ZIP (5 KB) - TINA-TI Spice model
Supported products & hardware
Package Pins CAD symbols, footprints & 3D models
VQFN (RGV) 16 Ultra Librarian
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