CPC G01D 5/3473 (2013.01) | 10 Claims |
1. A signal processing circuit of an optical encoder, the optical encoder comprising a first index photodiode, a second index photodiode and a reference index photodiode, the signal processing circuit comprising:
a trans-impedance amplifier (TIA), electrically coupled to the first index photodiode, the second index photodiode and the reference index photodiode, and configured to convert a first photocurrent generated by the first index photodiode, a second photocurrent generated by the second index photodiode and a reference photocurrent generated by the reference index photodiode respectively to a first voltage, a second voltage and a reference voltage;
a first comparator, configured to compare the first voltage and the reference voltage to output a first comparison voltage;
a second comparator, configured to compare the second voltage and the reference voltage to output a second comparison voltage; and
an AND gate, configured to receive the first comparison voltage and the second comparison voltage to accordingly generate an index output.
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