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Measurement of Low Level Signals

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Measuring of Low Level Signals

The basis of Measuring Circuits is Differential Bridge Pic.1, where difference of Potentials is determined by a formula: . Differential switching of Operational Amplifier (Pic.2) enables to decrease the Interference Common-mode Signal on 40 dB. It not always enables to measure Low Level Signals. Good result can be attained using a method of Phase Compensation (Pic.3).

Pic.1. Differential Bridge.

Pic.2. Operational Amplifier Circuit Differential Switching.

Pic.3. Phase Compensation Circuit.

Pic.4. Interference Common-mode Signal Compensation Circuit more than 80 dB. Amplification Factor is set by Resistor R1. Resistor R2 – Common-mode Rejection Factor. Circuit allows measuring signals less than 50 mV with the Interference 0.1 V.

Pic.4. Interference Common-mode Signal Compensation Circuit on 80 dB.

Pic.5. Interference Common-mode Signal Compensation Circuit on 90 dB.

Reduction of Interference Common-mode on 90 dB is possible to get using compensation in the Input of Operational Amplifier (Pic.5).

added 18.07.07 01:03:15 | looked over 7816 times