This work presents a low noise active pixel sensor. It uses one additional transistor compared to standard 4T pixel to obtain 1/f noise reduction and high conversion gain. 1/f noise is reduced by periodically switching the in-pixel source follower between depletion and inversion. The depletion state is achieved by re-configuring the source follower into a MOS capacitor and depleting the channel by controlling the source-drain terminal. The state change of the in-pixel source follower also enhances the conversion gain. The test chip has a $64 \times 64$ pixel array with a $10~ {\mu }\text{m}$ pixel pitch fabricated in 350 nm AMS process. The measured integrated noise of a pixel in the frequency band 128 Hz to 50 KHz is $728~ {\mu V_{rms}}$ without switching. At a switching frequency of 4 MHz, the integrated noise reduces to $306~ {\mu V_{rms}}$ after switching resulting in a 7.5 dB reduction. The input referred noise is reduced from $26 {e_{rms}^{-}}$ to $7.3 {e_{rms}^{-}}$ after applying switching. When both, switching and conversion gain enhancement are applied, the input referred noise is further reduced to $2.3 {e_{rms}^{-}}$ with an enhanced conversion gain of $398\,\, {\mu V/e^{-}}$ .

中文翻译：

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具有像素内 1/ f 降噪和转换增益调制功能的 2.3erms⁻ 时间噪声 CMOS 图像传感器，适用于低光成像

这项工作提出了一种低噪声有源像素传感器。与标准 4T 像素相比，它使用了一个额外的晶体管来获得 1/f 降噪和高转换增益。通过在耗尽和反转之间周期性地切换像素内源跟随器来降低 1/f 噪声。耗尽态是通过将源极跟随器重新配置为MOS电容并通过控制源漏端耗尽沟道来实现的。像素内源极跟随器的状态变化也提高了转换增益。测试芯片有 $64 \times 64$ 像素阵列与 $10~ {\mu }\text{m}$ 在 350 nm AMS 工艺中制造的像素间距。在 128 Hz 至 50 KHz 频带内测得的像素积分噪声为 $728~ {\mu V_{rms}}$ 无需切换。在 4 MHz 的开关频率下，集成噪声降低到 $306~ {\mu V_{rms}}$ 切换后降低 7.5 dB。输入参考噪声从 $26 {e_{rms}^{-}}$ 至 $7.3 {e_{rms}^{-}}$ 应用切换后。当同时应用开关和转换增益增强时，输入参考噪声进一步降低到 $2.3 {e_{rms}^{-}}$ 具有增强的转换增益 $398\,\, {\mu V/e^{-}}$ .