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US 12,015,427 B2Granted
Photodiode current compatible input stage for a sigma-delta analog-to-digital converter
AssigneeSTMicroelectronics (Research & Development) Limited
InventorsIlina Todorova, Jeffrey M. Raynor
Life of this patent
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Abstract
An input stage circuit for a sigma-delta analog-to-digital converter circuit receives a digital-to-analog converter generated feedback signal and an analog current input signal to generate a difference signal applied to an integrator circuit. A single bit quantization circuit quantizes an output of the integrator circuit to generate a bit signal that is applied to an input of the digital-to-analog converter. The input stage circuit includes a switched input capacitor controlled by first and second, non-overlapping, clock signals.
Claims29
A circuit including a sigma-delta analog-to-digital converter circuit, comprising:
- an integrator circuit configured to integrate a difference signal;
- a single bit quantization circuit configured to quantize an output of the integrator circuit and generate a bit signal;
- a feedback digital-to-analog converter circuit configured to generate an analog feedback signal from said bit signal;
- and
- an input stage circuit comprising:
- an input capacitor having a first terminal and further having a second terminal coupled to receive said analog feedback signal;
- a first switch coupled between an analog current signal input and the first terminal of the input capacitor, said first switch actuated in response to a first clock signal;
- a second switch coupled between the first terminal of the input capacitor and a reference node, said second switch actuated in response to a second clock signal;
- wherein said first and second clock signals are non-overlapping;
- a third switch coupled between the second terminal of the input capacitor and the reference node, said third switch actuated in response to the first clock signal;
- and
- a fourth switch coupled between the second terminal of the input capacitor and an input of the integrator circuit to provide said difference signal, said fourth switch actuated in response to the second clock signal;
- and
- wherein said analog current signal input is configured to receive a photocurrent generated by a photodiode, and further comprising a fifth switch coupled between the analog current signal input and the reference node, said fifth switch actuated to reset said photodiode.
11 more elements
A circuit including a sigma-delta analog-to-digital converter circuit, comprising:
- an integrator circuit configured to integrate a difference signal;
- a single bit quantization circuit configured to quantize an output of the integrator circuit and generate a bit signal;
- a feedback digital-to-analog converter circuit configured to generate an analog feedback signal from said bit signal;
- and
- an input stage circuit comprising:
- an input capacitor having a first terminal and further having a second terminal coupled to receive said analog feedback signal;
- a first switch coupled between an analog current signal input and the first terminal of the input capacitor, said first switch actuated in response to a first clock signal;
- a second switch coupled between the first terminal of the input capacitor and a reference node, said second switch actuated in response to a second clock signal;
- wherein said first and second clock signals are non-overlapping;
- a third switch coupled between the second terminal of the input capacitor and the reference node, said third switch actuated in response to the first clock signal;
- and
- a fourth switch coupled between the second terminal of the input capacitor and an input of the integrator circuit to provide said difference signal, said fourth switch actuated in response to the second clock signal;
- wherein said feedback digital-to-analog converter circuit comprises:
- a feedback capacitor having a first terminal and a second terminal;
- a fifth switch coupled between the first terminal and an output of the single bit quantization circuit, said fifth switch actuated in response to the second clock signal;
- a sixth switch coupled between the first terminal of the feedback capacitor and the reference node, said sixth switch actuated in response to the first clock signal;
- a seventh switch coupled between the second terminal of the feedback capacitor and the reference node, said seventh switch actuated in response to the first clock signal;
- and
- an eighth switch coupled between the second terminal of the feedback capacitor and the second terminal of the input capacitor, said eighth switch actuated in response to the second clock signal.
16 more elements
A circuit including a sigma-delta analog-to-digital converter circuit, comprising:
- an integrator circuit configured to integrate a difference signal;
- a single bit quantization circuit configured to quantize an output of the integrator circuit and generate a bit signal;
- a feedback digital-to-analog converter circuit configured to generate an analog feedback signal from said bit signal;
- and
- an input stage circuit comprising:
- an input capacitor having a first terminal and a second terminal;
- a first switch coupled between an analog current signal input and the first terminal of the input capacitor, said first switch actuated in response to a first clock signal;
- a second switch coupled between the first terminal of the input capacitor and an output of the feedback digital-to-analog converter circuit to receive said analog feedback signal, said second switch actuated in response to a second clock signal;
- wherein said first and second clock signals are non-overlapping;
- a third switch coupled between the second terminal of the input capacitor and a reference node, said third switch actuated in response to the first clock signal;
- and
- a fourth switch coupled between the second terminal of the input capacitor and an input of the integrator circuit to provide said difference signal, said fourth switch actuated in response to the second clock signal;
- and
- wherein said analog current signal input is configured to receive a photocurrent generated by a photodiode, and further comprising a fifth switch coupled between the analog current signal input and the reference node, said fifth switch actuated to reset said photodiode.
11 more elements
A circuit including a sigma-delta analog-to-digital converter circuit, comprising:
- an integrator circuit configured to integrate a difference signal;
- a single bit quantization circuit configured to quantize an output of the integrator circuit and generate a bit signal;
- a feedback digital-to-analog converter circuit configured to generate an analog feedback signal from said bit signal;
- and
- an input stage circuit comprising:
- an input capacitor having a first terminal and a second terminal, wherein the second terminal is coupled to a reference node;
- a first switch coupled between an analog current signal input and the first terminal of the input capacitor, said first switch actuated in response to a first clock signal;
- a second switch coupled between the first terminal of the input capacitor and the reference node, said second switch actuated in response to a reset signal;
- a third switch coupled between the first terminal of the input capacitor and an input of the integrator circuit, said third switch actuated in response to a second clock signal;
- wherein said first and second clock signals and said reset signal are non-overlapping;
- and
- a fourth switch coupled between an output of the feedback digital-to-analog converter circuit to receive said analog feedback signal and the input of the integrator circuit, said fourth switch actuated in response to the first clock signal.
9 more elements
Dependencies are inferred from the claim text.