Patent ID: 8324905

Claim:
An automatic two gain amplifier for use in conditioning an ion current signal sensed by an ion sensor in a combustion chamber of an engine, comprising: an ion peak detector configured to receive the ion current signal from the ion sensor, the ion peak detector generating a an ion peak detector output approximating a peak magnitude of the ion current signal; a comparator coupled to the ion peak detector and configured to compare the ion peak detector output with a threshold value, the comparator generating a first output when the ion peak detector output is greater than the threshold value and a second output when the ion peak detector output is less than the threshold value; and an amplification circuit operatively coupled to the comparator and configured to receive the ion current signal, and the amplification circuit further configured to amplify the ion signal by a first amplification when the first output is generated by the comparator and to amplify the ion signal by a second amplification when the second output is generated by the comparator.