Circuit for automatic regulation of a differential amplifier's gain

A circuit which regulates gain in a differential amplifier having first and second outputs, comprising:

• a fully differential amplifier receiving the first and second outputs, the fully differential amplifier having a first gain applied to the first output and a second gain applied to the second output to produce first and second amplified outputs;
• a comparison circuit which compares the amplified first and second amplified outputs with a reference and produces an output signal if either the first or second amplified output exceeds the reference, and wherein the comparison circuit comprises a comparator having multiple inputs which are compared with the reference;
• and
• a processing circuit, connected to receive the output signal from the comparison circuit, to generate a regulating signal dependent upon a duration of the output signal, the processing circuit comprising:
• a charge pump receiving the output signal from the comparison circuit and producing a control voltage;
• and
• a voltage to current converter receiving the control voltage from the charge pump and producing a control current therefrom, the control current operating as the regulating signal which regulates the gain of the differential amplifier.

A method of regulating a gain of a variable gain differential amplifier having output signals, comprising:

• amplifying the output signals to produce amplified signals;
• comparing the amplified signals with a reference in a comparison circuit;
• and
• if either amplified signal exceeds the reference, generating a regulating signal to reduce the gain of the variable gain differential amplifier.