Automatic Variable Gain Amplifier
AssigneeWoodward Governor Company
InventorJeffrey B. Barrett
Life of this patent
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Abstract
An automatic variable gain amplifier is provided. The automatic variable gain amplifier automatically adjusts the amplification of a signal, and in one embodiment, an ion signal, based on the amplitude of the peaks of the signal. The automatic variable gain amplifier detects the peaks of the signal, compares them to a threshold value, and, based on this comparison, varies the amount by which the signal is amplified. The automatic variable gain amplifier produces a composite output waveform for an input waveform with an amplitude that may vary over a plurality of orders of magnitude.
Claims20
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.
A method of conditioning an ion current signal generated by an ion current sensor positioned within a combustion chamber, the ion current signal having a first peak and a second peak that may be twenty to one hundred times smaller than the first peak, comprising the steps of:
- converting the ion current signal to a voltage signal;
- tracking a peak magnitude of the voltage signal;
- comparing the peak magnitude to a threshold;
- and
- amplifying the voltage signal by a variable gain based on a relationship between the peak magnitude and the threshold.
An ion current signal conditioning circuit for use in the control of an engine, the ion current signal having a first peak and a second peak, comprising:
- an ion current sensor positioned within a combustion chamber of the engine;
- a resistor coupled to the ion current sensor to generate an ion current voltage signal thereacross;
- an ion peak detector configured to receive the ion current voltage signal, the ion peak detector generating a an ion peak detector output approximating a peak magnitude of the ion current voltage 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.
Dependencies are inferred from the claim text.