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JSSC 2020第9期Data Converters0.18-µmSAR ADC

Bandwidth-Enhanced Oversampling Successive Approximation Readout Technique for L

提出带宽增强型过采样逐次逼近读出技术,降低MEMS电容加速度计噪声并提高能效
0.18-µm BCD工艺,飞法级电容检测
MEMS电容加速度计噪声降低能效优化过采样技术
创新点1:带宽增强型过采样技术(方法创新)——通过创新的BE-OSA技术,在不增加放大器跨导的情况下显著提升SC CVC的采样频率,从而有效降低噪声基底至0.9 aF/√Hz,相比传统方法(2.5 aF/√Hz)提升2.7倍。
创新点2:低功耗开关电容电容-电压转换器设计(电路创新)——优化SC CVC结构,在0.18-µm BCD工艺下实现243 fJ的绝对能效指标(FoM2),相比同类开关电容读出电路达到最佳能效。
创新点3:系统级能效优化(系统创新)——通过协同设计前端SC CVC与后端ADC,实现相对能效指标FoM3=0.14,在保持开环结构低功耗优势的同时突破femto-farad级电容检测限制。
创新点4:寄生电容噪声抑制技术(电路创新)——针对MEMS加速度计寄生电容热噪声问题,提出新型采样时序控制方法,在femto-farad级信号检测中实现非线性误差补偿。
Abstract
The bandwidth-enhanced oversampling successive approximation (BE-OSA) readout technique is proposed in this article to reduce the noise floor of the readout circuit for micro-electromechanical systems (MEMS) capacitive accelerome- ter while achieving high power efficiency in terms of the figure of merit (FoM). The open-loop structure has been widely used in MEMS capacitive accelerometer for the Internet of Things (IoT) applications due to its low power consumption. However, in the open-loop acceler