An active electrode having a closed-loop unit-gain amplifier with chopper modulation

A technology of active electrode and integrated amplifier, which is applied to the sensor system for sensing potential difference and the field of potential difference in sensing sensor system, to achieve good shielding performance, improved power supply rejection ratio, and ultra-high input impedance.

Active Publication Date: 2017-08-29
T&W ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, surrounding coupled disturbances can easily be on the millivolt or even volt level

Method used

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  • An active electrode having a closed-loop unit-gain amplifier with chopper modulation
  • An active electrode having a closed-loop unit-gain amplifier with chopper modulation
  • An active electrode having a closed-loop unit-gain amplifier with chopper modulation

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Embodiment Construction

[0029] figure 1 An active electrode design according to one embodiment of the invention is schematically shown. Biopotential signal V in (t) is sensed by a capacitive electrode (not shown) and fed to the input of the integrated amplifier 10 . Impedance Z s Indicates skin electrode impedance. At the input of the integrated amplifier 10, the biopotential signal V in (t) Modulation. The integrated amplifier 10 has a gain A equal to 1 v , whereby the integrated amplifier 10 acts as a buffer, and by applying the same chopped modulation signal m(t) also in the second mixer 12 on the output of the integrated amplifier 10, the integrated amplifier 10 and the two mixers 11 and 12 provide the output output signal V out (t) buffer path.

[0030] exist figure 1The modulation signal m(t) employed in the embodiment shown in is shown as a pulse width modulated signal with a duty cycle of 50%, and exhibits unit amplitudes of +1 and -1. Select the chopping frequency f chop , to ensu...

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Abstract

An active electrode has an electrode for sensing an electric potential and generating an input signal, and a shield placed near said electrode but being electric insulated from the electrode. An integrated amplifier (10) has an input connected to the at least one electrode for receiving the input signal, and providing a buffered path outputting a buffered output signal. The shield being connected to said output of the integrated amplifier to actively drive the electrical potential of said shield, thereby providing an active shielding of said electrode. The buffered path includes a first mixer (11) in front of the integrated amplifier for frequency shifting the input signal from a basic frequency range to a higher frequency range, and a second mixer (12) on the output of the integrated amplifier for frequency shifting the amplified signal from said higher frequency range back to said basic frequency range. The active electrode may be used for recording EEG signals.

Description

technical field [0001] The present invention relates to electric field sensors. The invention more particularly relates to electric field sensors for sensing potential differences, eg biopotential signals, and generating input signals for signal processing. The sense electrodes are protected by actively driven shields to minimize capacitively coupled noise and to minimize capacitive loading of the source signal. Furthermore, the invention relates to a sensor system for sensing potential differences. Furthermore, the invention relates to a method for sensing a potential difference in a sensor system. Background technique [0002] Active electrodes are widely used for biopotential recording and are especially suitable for advanced electrode technologies such as non-contact and dry contact electrodes. The purpose of using active electrodes is to shield the electrodes from external interference and to compensate for parasitic capacitance. [0003] Active electrodes generally...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B5/00A61B5/04A61B5/0478H03F3/393H03F3/45A61B5/288A61B5/308
CPCA61B5/6803H03F3/393H03F3/45179H03F3/45183H03F3/45475H03F2203/45306H03F2200/261H03F2200/271A61B5/6817A61B5/30A61B5/291A61B5/7225A61B5/28A61B5/7203A61B5/308A61B5/31H03F3/38A61B2562/0209A61B5/25H03F1/26H03F1/523H03G3/20H04R25/353H04R25/505H04R2225/43H04R2225/67
Inventor P·基德姆斯X·周S·基尔斯戈德Q·李
Owner T&W ENG
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