Precision High-Speed Logarithmic Amplifier with 2.5V Reference and Uncommitted Output Op Amps
Product details
Parameters
Package | Pins | Size
Features
- 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
- STABILE OVER TEMPERATURE
- LOW QUIESCENT CURRENT: 10mA
- DUAL OR SINGLE SUPPLY: ±5V, +5V
- PACKAGE: Small QFN-16 (4mm x 4mm)
- SPECIFIED TEMPERATURE RANGE: –5°C to +75°C
- APPLICATIONS
- ONET ERBIUM-DOPED FIBER OPTIC AMPLIFIER (EDFA)
- LASER OPTICAL DENSITY MEASUREMENT
- PHOTODIODE SIGNAL COMPRESSION AMP
- LOG, LOG-RATIO FUNCTION
- ANALOG SIGNAL COMPRESSION IN FRONT OF ANALOG-TO-DIGITAL (ADC) CONVERTER
- ABSORBANCE MEASUREMENT
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Description
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 ensured 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 may 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 out per decade of input current, which limits the output so that it fits within a 5V or 10V range. The output can be scaled and offset with one of the available additional amplifiers, so it 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.
Technical documentation
| Type | Title | Date | |
|---|---|---|---|
| * | Datasheet | Single-Supply, High-Speed, Precision Logarithmic Amplifier datasheet (Rev. A) | Mar. 19, 2007 |
| User guides | LOG114EVM User Guide | Sep. 29, 2011 | |
| More literature | Log Amp Basics Part 2: Design Example for LOG114 [WMV] | Feb. 19, 2010 |
Design & development
For additional terms or required resources, click any title below to view the detail page where available.Hardware development
Description
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 (...)
Features
- Easy to use
- High Speed + Precision
- Wide Input Dynamic Range
- Operates on a single 5V supply
- PCB footprint provided for photo diode or resistor input
Design tools & simulation
CAD/CAE symbols
| Package | Pins | Download |
|---|---|---|
| VQFN (RGV) | 16 | View options |
Ordering & quality
Support & training
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