Dual CTIA for non-pinched photodiode

The readout circuit with a CTIA structure and polarization reset block addresses the challenge of maintaining polarization and high-frequency operation in non-pinched photodiodes, improving depth image acquisition systems by ensuring stable photodiode polarization and compact pixel size.

FR3138963B1Active Publication Date: 2026-04-10COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
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Patent Information

Application Number
FR2022008374
Authority / Receiving Office
FR · FR
Patent Type
Patents
Current Assignee / Owner
Filing Date
2022-08-18
Publication Date
2026-04-10
Estimated Expiration
2042-08-18

AI Technical Summary

Technical Problem

Existing readout circuits for non-pinched photodiodes in depth image acquisition systems face challenges in maintaining polarization while allowing high-frequency operation and minimizing pixel size, particularly in materials like InGaAs, which are difficult to implement with traditional cascode structures.

Method used

A readout circuit with a transimpedance capacitive amplifier (CTIA) structure and a polarization reset block is used, incorporating a feedback branch with an integration capacitor and a repolarization switch to maintain photodiode polarization during sampling phases, allowing high-frequency operation and reduced pixel size.

Benefits of technology

The solution ensures stable photodiode polarization and high-frequency operation, enhancing the performance of depth image acquisition systems, especially with non-pinched photodiodes like InGaAs, while maintaining a compact pixel size.

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Abstract

Depth image acquisition device of a scene, the acquisition device having a plurality of depth pixels each comprising a readout circuit having a first integration capacitance (CINT1) for acquiring first samples of charges from the photodetector (PD) during first sampling phases (C0) carried out during an integration period comprising repeated sequences of several successive sampling phases (C0, C1, C2, C3) of charges, the first integration capacitance (CINT1) being located in a feedback branch between an input and an output of a first amplifier stage (A1) of a transimpedance capacitive amplifier structure, said input being connected to a detection node (ND) coupled to the photodetector (PD) and said output being connected to a readout node (NL1) coupled to an output stage (51) of said readout circuit,The reading circuit further comprises a polarization reset block (10) for polarizing the photodetector (PD), with a repolarization switch (11) configured to, during polarization reset phases of said photodetector (PD) performed between said first sampling phases, couple the polarization reset block (10) to the photodetector (PD) so as to apply a polarization potential to it. Figure for the abbreviation: 3.,
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