Logarithmic amplifier of small direct currents

1971 ◽  
Vol 14 (1) ◽  
pp. 74-77
Author(s):  
L. A. Vsevolozhskii
Keyword(s):  
Logarithmic Amplifier

scholarly journals High-CMRR Low-Noise Fully Integrated Front-End for EEG Acquisition Systems

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1157 ◽  
Author(s):  
Robert Chebli ◽  
Mohamed Ali ◽  
Mohamad Sawan
Keyword(s):  
Low Noise ◽  
Common Mode ◽  
Fully Integrated ◽  
Dc Offset ◽  
Chopper Stabilization ◽  
Logarithmic Amplifier ◽  
Offset Voltage ◽  
High Cmrr ◽  
Programmable Gain ◽  
Stabilization Technique

We present in this paper a fully integrated low-noise high common-mode rejection ratio (CMRR) logarithmic programmable gain amplifier (LPGA) and chopped LPGA circuits for EEG acquisition systems. The proposed LPGA is based on a rail-to-rail true logarithmic amplifier (TLA) stage. The high CMRR achieved in this work is a result of cascading three amplification stages to construct the LPGA in addition to the lower common-mode gain of the proposed logarithmic amplification topology. In addition, the 1 / f noise and the inherent DC offset voltage of the input transistors are reduced using a chopper stabilization technique. The CMOS 180 nm standard technology is used to implement the circuits. Experimental results for the integrated LPGA show a CMRR of 140 dB, a differential gain of 37 dB, an input-referred noise of 0.754 μ Vrms, a 189 μ W power consumption from 1.8 V power supply and occupies an active area of 0.4 mm 2 .

A Low-Noise, Low-Power, Wide Dynamic Range Logarithmic Amplifier for Biomedical Applications

2018 ◽  
Vol 27 (07) ◽  
pp. 1850104 ◽  
Author(s):  
Yuwadee Sundarasaradula ◽  
Apinunt Thanachayanont
Keyword(s):  
Low Power ◽  
Biomedical Applications ◽  
Dynamic Range ◽  
Supply Voltage ◽  
Low Noise ◽  
Power Supply Voltage ◽  
Wide Dynamic Range ◽  
Dc Offset ◽  
Limiting Amplifier ◽  
Logarithmic Amplifier

This paper presents the design and realization of a low-noise, low-power, wide dynamic range CMOS logarithmic amplifier for biomedical applications. The proposed amplifier is based on the true piecewise linear function by using progressive-compression parallel-summation architecture. A DC offset cancellation feedback loop is used to prevent output saturation and deteriorated input sensitivity from inherent DC offset voltages. The proposed logarithmic amplifier was designed and fabricated in a standard 0.18[Formula: see text][Formula: see text]m CMOS technology. The prototype chip includes six limiting amplifier stages and an on-chip bias generator, occupying a die area of 0.027[Formula: see text]mm2. The overall circuit consumes 9.75[Formula: see text][Formula: see text]W from a single 1.5[Formula: see text]V power supply voltage. Measured results showed that the prototype logarithmic amplifier exhibited an 80[Formula: see text]dB input dynamic range (from 10[Formula: see text][Formula: see text]V to 100[Formula: see text]mV), a bandwidth of 4[Formula: see text]Hz–10[Formula: see text]kHz, and a total input-referred noise of 5.52[Formula: see text][Formula: see text]V.

scholarly journals Magneto-Impedance Sensor Driven by 400 MHz Logarithmic Amplifier

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 355 ◽  
Author(s):  
Tomoo Nakai
Keyword(s):  
Thin Film ◽  
High Frequency ◽  
High Sensitivity ◽  
Smart Manufacturing ◽  
Voltage Controlled Oscillator ◽  
High Frequency Signal ◽  
Logarithmic Amplifier ◽  
Impedance Variation ◽  
Voltage Signal ◽  
Impedance Sensor

A thin-film magnetic field sensor is useful for detecting foreign matters and nanoparticles included in industrial and medical products. It can detect a small piece of tool steel chipping or breakage inside the products nondestructively. An inspection of all items in the manufacturing process is desirable for the smart manufacturing system. This report provides an impressive candidate for realizing this target. A thin-film magneto-impedance sensor has an extremely high sensitivity, especially, it is driven by alternatiing current (AC) around 500 MHz. For driving the sensor in such high frequency, a special circuit is needed for detecting an impedance variation of the sensor. In this paper, a logarithmic amplifier for detecting a signal level of 400 MHz output of the sensor is proposed. The logarithmic amplifier is almost 5 mm × 5 mm size small IC-chip which is widely used in wireless devices such as cell phones for detecting high-frequency signal level. The merit of the amplifier is that it can translate hundreds of MHz signal to a direct current (DC) voltage signal which is proportional to the radio frequency (RF)signal by only one IC-chip, so that the combination of a chip Voltage Controlled Oscillator (VCO), a magneto-impedance (MI) sensor and the logarithmic amplifier can compose a simple sensor driving circuit.

CDTA based logarithmic amplifier

2012 ◽  
Author(s):  
Mohammad A. Maktoomi ◽  
R. K. Mishra ◽  
Muzaffar A. Siddiqi ◽  
M. Prem Pyari
Keyword(s):  
Logarithmic Amplifier
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