Integrated optical biosensor array including charge injection circuit and quantizer circuit
View Patent ↗An optical biosensor pixel for detecting the amount of light that is generated by the biosensing process and a biosensor array architecture that includes such biosensor pixels. The optical biosensor pixel includes a photodiode configured to convert an incident photon flux into a current. Additionally, the optical biosensor pixel includes an optical filter configured to select specific wavelengths and/or photon flux angles to reach the photodiode from a biological sample. The biosensor pixel further includes a trans-impedance amplifier coupled to the photodiode, where the trans-impedance amplifier is configured to convert the current into a voltage signal. Additionally, the biosensor pixel includes a 1-bit comparator coupled to the trans-impedance amplifier and a 1-bit digital-to-analog converter coupled to the 1-bit comparator, where the 1-bit digital-to-analog converter injects different levels of charge into an input of the trans-impedance amplifier at each cycle based on an output of the 1-bit comparator.
1. An optical biosensor pixel, comprising:
an integrated photodiode configured to convert an incident photon flux into a current;
an integrated optical filter coupled to said integrated photodiode, wherein said integrated optical filter is configured to select specific wavelengths and/or photon flux angles to reach said integrated photodiode from a biological sample;
a trans-impedance amplifier coupled to said integrated photodiode, wherein said trans-impedance amplifier is configured to convert said current into a voltage signal;
a quantizer circuit coupled to said trans-impedance amplifier, wherein said quantizer circuit is configured to convert a value of said voltage signal into a digital value;
a charge injection circuit coupled to said quantizer circuit, wherein said charge injection circuit is configured to place a fixed amount of net charge directly added to or subtracted from an input of said trans-impedance amplifier; and
a feedback network coupled to said quantizer circuit, wherein said feedback network comprises said charge injection circuit, wherein said feedback network is configured to control an operation of said charge injection circuit based on values of said digital value.
2. The optical biosensor pixel as recited in claim 1 , wherein said trans-impedance amplifier comprises a capacitance trans-impedance amplifier circuit.
3. An optical biosensor pixel, comprising:
an integrated photodiode configured to convert an incident photon flux into a current;
an optical filter coupled to said integrated photodiode, wherein said optical filter is configured to select specific wavelengths and/or photon flux angles to reach said integrated photodiode from a biological sample;
a trans-impedance amplifier coupled to said integrated photodiode, wherein said trans-impedance amplifier is configured to convert said current into a voltage signal;
a controlled voltage source coupled to a positive input of said trans-impedance amplifier;
a 1-bit comparator coupled to said trans-impedance amplifier; and
a 1-bit digital-to-analog converter coupled to said 1-bit comparator, wherein said 1-bit digital-to-analog converter injects different levels of charge into an input of said trans-impedance amplifier at each cycle based on an output of said 1-bit comparator thereby subtracting a fixed charge at a next cycle from said current generated by said integrated photodiode.
4. The optical biosensor pixel as recited in claim 3 , wherein said trans-impedance amplifier comprises a capacitance trans-impedance amplifier circuit.
5. The optical biosensor pixel as recited in claim 3 , wherein a low-amplitude white noise source is inputted to said 1-bit comparator.
6. A biosensor array architecture, comprising:
a plurality of pixels assembled in rows and columns, wherein each of said plurality of pixels comprises:
an integrated photodiode configured to convert an incident photon flux into a current;
an optical filter coupled to said integrated photodiode, wherein said optical filter is configured to select specific wavelengths and/or photon flux angles to reach said integrated photodiode from a biological sample;
a trans-impedance amplifier coupled to said integrated photodiode, wherein said trans-impedance amplifier is configured to convert said current into a voltage signal;
a controlled voltage source coupled to a positive input of said trans-impedance amplifier;
a 1-bit comparator coupled to said trans-impedance amplifier; and
a 1-bit digital-to-analog converter coupled to said 1-bit comparator, wherein said 1-bit digital-to-analog converter injects different levels of charge into an input of said trans-impedance amplifier at each cycle based on an output of said 1-bit comparator thereby subtracting a fixed charge at a next cycle from said current generated by said integrated photodiode; and
row and column deciders coupled to said plurality of pixels, wherein said row and column deciders are configured to select individual pixels of said plurality of pixels.
7. The biosensor array architecture as recited in claim 6 further comprises:
a row decoder coupled to said plurality of pixels, wherein said row decoder is configured to select a specific row within said biosensor array architecture.
8. The biosensor array architecture as recited in claim 6 further comprises:
a power management circuit configured to ensure that each of said plurality of pixels receive an appropriate supply and reference voltage.