Circuit and method for reducing bias noise in amplifier circuits

An amplifier circuit for reducing bias noise comprising:

• a sensor for selectively generating a sensor output;
• a first amplifier for selectively generating an amplifier output responsive to the sensor output comprising:
• a passive biasing source for supplying a desired bias signal to the first amplifier;
• an active biasing source for energizing the passive biasing source to supply the desired bias signal;
• a first decoupler for selectively decoupling the active biasing source from the passive biasing source when the amplifier is configured for amplifying the sensor output so that the amplifier remains isolated from electronic noise produced by the active biasing source while still being supplied the desired bias signal by the passive source;
• a sampling circuit coupled to an output of the first amplifier for selectively sampling the amplifier output of the first amplifier;
• and
• a controller for controlling a timing of an operation of the sampling circuit relative to an operation of the sensor and an operation of the first amplifier to generate an offset corrected output.

A method for reducing bias noise in a amplifier circuit comprising:

• providing a passive biasing source for supplying a desired bias signal to an amplifier;
• providing an active biasing source for energizing the passive biasing source to supply the desired bias signal;
• energizing the passive biasing source with the active biasing source;
• and
• selectively decoupling the active biasing source from the passive biasing source when the amplifier is configured for amplifying a signal so that the amplifier remains isolated from electronic noise produced by the active biasing source while still being supplied the desired bias signal by the passive source.