IEEE Trans Biomed Circuits Syst. 2019 Apr;13(2):387-395. doi: 10.1109/TBCAS.2019.2897287. Epub 2019 Feb 4.
High-throughput recordings of small current are becoming more common in biosensor applications, including in vivo dopamine measurements, single-cell electrophysiology, photoplethysmography, 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 μm 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.
高通量小电流记录在生物传感器应用中越来越常见，包括体内多巴胺测量、单细胞电生理学、光体积描记法、脉搏血氧饱和度测定和纳米孔记录。因此，需要一种高度可扩展的跨阻放大器设计。半共享放大器设计是通过为许多反相半部分共享运算放大器设计的非反相侧来提高可扩展性的一种方法。与使用独立运算放大器相比，这种方法将硅面积和功率减少近一半。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单个非反相半部分的反相半部分放大器数量的权衡。使用半共享结构设计了跨阻放大器，以最小化每个放大器的尺寸。跨阻放大器基于电容器的电流积分。由于积分放大器未达到稳态，因此是一个非稳态电路，因此其噪声分析是一项具有挑战性的任务。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。使用标准的 0.35 μm 工艺制造了 1024 个跨阻放大器的阵列设计，并进行了测试以确认上述分析的有效性。放大器阵列在跨阻增益（高增益时为 7.00 mV/pA，低增益时为 0.86 mV/pA）、整个 1024 个放大器阵列中低至 1.65 mV 的低失配以及极低噪声方面表现出很高的线性度。该技术对于制造更大的阵列以实现用于生物传感器应用的更高吞吐量测量工具至关重要。
