A-M Systems 1700 Handbuch - Seite 10

Blättern Sie online oder laden Sie pdf Handbuch für Verstärken A-M Systems 1700 herunter. A-M Systems 1700 16 Seiten. Four-channel differential ac amplifier

Seite drucken

Stimulus Mode

In Stimulus Mode, the

to apply the stimulation signal to the electrode. All amplification circuits are grounded in

this mode, and the

Record Mode

In Record Mode, the signal from the

a high impedance, low noise differential amplifier stage consisting of two operational

amplifiers with x10 gain. Direct coupling reduces the errors typically associated with

capacity input coupling. The operational amplifiers are in non-inverting mode and their

gain-setting networks connect through a common resistor to preserve high common-

mode rejection.

The common-mode voltage of the input signal at the inverting inputs of the operational

amplifiers is measured, and is used to drive the electrode cable shield. This improves

the common-mode rejection performance of the input amplifier stage. For this reason,

the driven shield should not be grounded.

The output signals are then connected to a second differential operational amplifier

circuit with a gain of x10. At this point, the differential electrode signal has been

amplified by x100 and converted to a single-ended signal with respect to ground. An

internal CMR potentiometer is trimmed at the factory to maximize the common-mode

rejection.

The signal passes through a double-pole low-pass filter, which attenuates frequencies

above the

HIGH CUT-OFF

If selected, the signal next passes through the Notch Filter. The Notch Filter is tuned

to the power line frequency and consists of a twin-T network in a feedback loop with an

operational amplifier. This stage does not amplify the signal.

The signal then passes through a double-pole high-pass filter, which attenuates

frequencies below the

the final amplifier which provides x1, x10 or x100 gain to produce an output signal

according to the total gain specified by the

A-M Systems

Theory of Operation

connector is connected internally to the

INPUT

connector is disabled.

OUTPUT

INPUT

switch setting. This stage provides no signal amplification.

switch setting. Also included in this stage is

LOW CUT-OFF

131 Business Park Loop, P.O. Box 850 Carlsborg, WA 98324

Telephone: 800-426-1306 * 360-683-8300 * FAX: 360-683-3525

E-mail: [email protected] * Website:

connector is coupled directly to the inputs of

switch.

GAIN

http://www.a-msystems.com

connector

STIMULUS