Driven Right Leg Circuit

From: Mar Malp <mar.malp_at_katamail.com>
Date: Wed, 24 Mar 2010 18:45:19 +0100

Salve a tutti!

Qualcuno pu� spiegarmi semplicemente come funziona il circuito in oggetto?
In rete ho trovato questa definizione, che mi sembra chiara:

A Driven Right Leg Circuit or "DRL" circuit is an electric circuit that is
often added to biological signal amplifiers to reduce Common-mode
interference. Biological signal amplifiers such as EKG (Electrocardiogram)
EEG (Electroencephalogram) or EMG circuits measure very small electrical
signals emitted by the body, often as small as several micro-volts
(millionths of a volt). Unfortunately, the patient's body can also act as an
antenna which picks up electromagnetic interference, especially 50/60Hz
noise from electrical power lines. This interference can obscure the
biological signals, making them very hard to measure. Right Leg Driver
circuitry is used to eliminate interference noise by actively canceling the
interference.

Da quel che ho capito:

http://topserver.mi.infn.it/mies/elettronica_ii/Tutorial/OPAmps/op1ae.htm

si pulisce, quindi, Vu da Vc*Ac inviando all'ingresso, tramite il terzo
elettrodo, -Vc: � corretto?
Ma se � corretto, come fa il terzo elettrodo a far si ch� all'istante t vi
sia a livello degli altri due elettrodi *anche* la tensione -Vc? Iniettando
corrente? E in quale ammontare?

Qui uno schema elettrico semplificato:
http://openeeg.sourceforge.net/doc/modeeg/images/amp_block_diagram.gif

Grazie,
Marcello
Received on Wed Mar 24 2010 - 18:45:19 CET

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