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本文论述用于测量细胞膜离子通道电流的放大器的电路方案 .因被测电流在 1pA到nA级的范围内 ,而输出电压要求达到计算机便于处理的数值 .故需采用多级放大电路 .被测电流属极微弱的信号 ,噪声问题是设计中的关键 .对于多级放大器来说 ,前置放大级 (探头电路 )的低噪声设计至关重要 .文中分析放大电路中的主要元、器件的背景噪声 ,用噪声电流和噪声电压的功率密度谱 (PDS)SI(f)和Sv(f)来表征其特性 .给出了所设计的PC Ⅱ型膜片钳放大器的主要性能参数和记录的电流波形 .
This article discusses the circuit scheme for an amplifier that measures the ion channel current in a cell membrane. Since the measured current is in the range of 1pA to nA and the output voltage is required to reach the computer’s ease of processing, multi-stage amplification is required. Is a very weak signal, the noise problem is the key to the design.For multi-stage amplifier, preamplifier stage (probe circuit) of the low noise design is crucial.This paper analyzes the main elements of the amplifier circuit, the background noise of the device , And their characteristics are characterized by the power density spectrum (PDS) SI (f) and Sv (f) of the noise current and the noise voltage.The main performance parameters and the recorded current waveforms of the designed PC Ⅱ type Patch-Clamp Amplifier .