Analysis of Simple Half-Shared Transimpedance Amplifier for Picoampere Biosensor Measurements
Analysis of Simple Half-Shared Transimpedance Amplifier for Picoampere Biosensor Measurements
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DOI：
10.1109/tbcas.2019.2897287
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发表时间：
2019-04-01
影响因子：
5.1
通讯作者：
Kim, Brian N.
中科院分区：
文献类型：
--
作者：
Mulberry, Geoffrey;White, Kevin A.;Kim, Brian N.
小电流的高通量记录在生物传感器应用中变得越来越常见，包括活体多巴胺测量、单细胞电生理学、光体积描记、脉搏血氧计和纳米孔记录。因此，需要一种高度可扩展的跨阻抗放大器设计。半共享放大器设计是通过将运算放大器的非反相侧共享给多个反相半部来提高可扩展性的一种方法。与使用独立运算放大器相比，这种方法减少了近一半的硅面积和功耗。在本文中，我们分析了一种简单的半共享放大器结构的可扩展性，同时研究了增加共享一个非反转一半的反转一半放大器的数量的权衡。采用半共用结构设计了一个跨阻放大器，使每个放大器的体积最小。跨阻放大器基于电容器的电流积分。积分放大器的噪声分析是一项具有挑战性的任务，因为它不能达到稳态，因此是一个非平稳电路。对于频率分析，讨论了一种转换方法来估计仿真中的噪声特性。采用0.35微米标准工艺制作了1024个跨阻放大器的阵列设计，并进行了测试，验证了上述分析的有效性。该放大器阵列在跨阻增益方面表现出高线性度(高增益为7.00 mV/pA，低增益为0.86 mV/pA)，整个1024放大器阵列的失配率为1.65 mV，噪声极低。该技术在制造更大的阵列以实现生物传感器应用的更高吞吐量测量工具方面将是至关重要的。
High-throughput recordings of small current are becoming more common in biosensor applications, including in vivo dopamine measurements, single-cell electrophysiology, photo-plethysmography, pulse oximetry, and nanopore recordings. Thus, a highly scalable transimpedance amplifier design is in demand. Half-shared amplifier design is one way to improve the scalability by sharing the non-inverting side of the operational amplifier design for many inverting halves. This method reduces silicon area and power by nearly half compared to using independent operational amplifiers. In this paper, we analyze the scalability of a simple half-shared amplifier structure while investigating the tradeoff of increasing the number of inverting half amplifiers sharing a single non-inverting half. A transimpedance amplifier is designed using the half-shared structure to minimize the size per amplifier. The transimpedance amplifier is based on a current integration of a capacitor. The noise analysis of the integration amplifier is a challenging task because it does not reach a steady-state, thus, being a non-stationary circuit. For frequency analysis, a conversion method is discussed to estimate the noise characteristic in the simulation. The array design of 1024 transimpedance amplifiers is fabricated using a standard 0.35 mu m process and is tested to confirm the validity of above analysis. The amplifier array exhibits high linearity in transimpedance gain (7.00 mV/pA for high gain and 0.86 mV/pA for low gain), low mismatch of 1.65 mV across the entire 1024 amplifier array, and extremely low noise. The technique will be crucial in enabling the fabrication of larger arrays to enable higher throughput measurement tools for biosensor applications.