Abstract

Alternating current (AC) sources which provide currents in micro ampere ranges have become essential for testing of electronic components, simulation of sensors, eddy current analysis, small signal analysis of transistors, electro-cutaneous stimulation in therapeutics, current injection in medical imaging techniques etc. This manuscript proposes a precise voltage mode AC source for extremely low current values. A simple AC source with load in the feedback is optimised experimentally by compensating the capacitive effects (approx. 4.7 pF) by employing a novel combination of general impedance converter (gic) or Negative Capacitance Converter (NCC) circuits along with basic circuit. The design is proposed with precise value of 160 \(\upmu A\) for applications including physiological measurements. It is seen that GIC circuit modification offers better consistency and performance in load analysis compared to NCC. Load analysis (10–2000 \(\Omega\)), frequency analysis (100 Hz to 1 MHz), stability analysis and reliability testing confirm the optimised and precise operation of the proposed current source. With very high degree of matching in theoretical and practical results, calculation of output impedance is also done and the value is fair enough. The hardware incorporates direct digital synthesis chip driven by a microcontroller for generation of sine wave, thereby reducing the need of bulky power supplies and function generators. This precise alternating current source is suitable for wide band portable applications.

中文翻译：

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精确，便携式和宽带交流电源，电流值极低

摘要

提供微安级电流的交流（AC）电源已成为电子元件测试，传感器仿真，涡流分析，晶体管小信号分析，治疗中的皮肤电刺激，医学成像技术中的电流注入等必不可少的部分该手稿提出了一种用于极低电流值的精确电压模式交流电源。通过采用通用阻抗转换器（gic）或负电容转换器（NCC）电路与基本电路的新颖组合，通过补偿电容效应（约4.7 pF），通过实验优化了带有反馈负载的简单交流电源。提出的设计精度为160  \（\ upmu A \）用于包括生理测量在内的应用。可以看出，与NCC相比，GIC电路修改在负载分析中提供了更好的一致性和性能。负载分析（10–2000  \（\ Omega \）），频率分析（100 Hz至1 MHz），稳定性分析和可靠性测试证实了所建议电流源的优化和精确操作。在理论和实践结果之间具有很高的匹配度，因此也可以完成输出阻抗的计算，并且该值足够合理。该硬件集成了由微控制器驱动的直接数字合成芯片，用于生成正弦波，从而减少了庞大的电源和函数发生器的需求。这种精确的交流电源适用于宽带便携式应用。