US 8,803,595 B2 · Common mode noise cancellation circuit for unbalanced signals

Abstract

This invention provides a common mode noise cancellation circuit for the unbalanced signals. The unbalanced signals come from a signal source with a first signal terminal and a second signal terminal having a first grounding potential. The common mode noise cancellation circuit comprises a grounding terminal and a subtractor. The grounding terminal with a second grounding potential is electrically coupled to the second signal terminal of the signal source through an impedance unit. The subtractor comprises a first receiving terminal, a second receiving terminal and a signal output terminal. The first receiving terminal and the second receiving terminal are electrically coupled to the first signal terminal and the second signal terminal respectively for receiving the unbalanced signals. The subtractor subtracts the noise coming from the first receiving terminal and the noise coming from the second receiving terminal to reduce the output noise of the signal output terminal.

Claims14

Dependent claims

A common mode noise cancellation circuit for the unbalanced signals, the unbalanced signals coming from a first signal terminal and a second signal terminal of a signal source, the second signal terminal having a first grounding potential, the common mode noise cancellation circuit comprising:

a grounding terminal, having a second grounding potential, the grounding terminal is electrically coupled to the second signal terminal of the signal source via an impedance unit;
and
a subtractor, comprising a first receiving terminal, a second receiving terminal and a signal output terminal, the first receiving terminal and the second receiving terminal are electrically coupled to the first signal terminal and the second signal terminal respectively, for receiving the unbalanced signals, the subtractor subtracting noise coming from the first signal terminal and noise coming from the second signal terminal from each other for reducing noise outputted by the signal output terminal.

A common mode noise cancellation circuit for the unbalanced signals receiving a first unbalanced input, a second unbalanced input and having a signal output terminal, comprising:

an operational amplifier operating in positive and negative voltage, comprising an inverted input terminal, a non-inverted input terminal and an output terminal, the output terminal electrically coupled to the signal output terminal of the cancellation circuit;
a first resistance unit, electrically coupled between the first unbalanced input and the inverted input terminal of the operational amplifier;
a second resistance unit, electrically coupled between the output terminal and the inverted input terminal of the operational amplifier;
a third resistance unit, electrically coupled between the second unbalanced input and the non-inverted input terminal of the operational amplifier;
a fourth resistance unit, electrically coupled between the grounding terminal and the non-inverted input terminal of the operational amplifier;
and
a charge pump circuit, generating a negative supply voltage as the negative voltage source of the operational amplifier.

4 more elements

Dependencies are inferred from the claim text.

Common mode noise cancellation circuit for unbalanced signals

Life of this patent

Common mode noise cancellation circuit for unbalanced signals

Life of this patent

Abstract

Claims14