Qureshi Tabassum R, Chatwin Chris R, Zhou Zhou, Li Nan, Wang W
School of Engineering & Informatics, University of Sussex, Brighton, UK.
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:1582-5. doi: 10.1109/EMBC.2012.6346246.
According to Jossient, interesting characteristics of breast tissues mostly lie above 1MHz; therefore a wideband excitation source covering higher frequencies (i.e. above 1MHz) is required. The main objective of this research is to establish a feasible bandwidth envelope that can be used to design a constant EIM voltage source over a wide bandwidth with low output impedance for practical implementation. An excitation source is one of the major components in bio-impedance measurement systems. In any bio-impedance measurement system the excitation source can be achieved either by injecting current and measuring the resulting voltages, or by applying voltages and measuring the current developed. This paper describes three voltage source architectures and based on their bandwidth comparison; a differential voltage controlled voltage source (VCVS) is proposed, which can be used over a wide bandwidth (>15MHz). This paper describes the performance of the designed EIM voltage source for different load conditions and load capacitances reporting signal-to-noise ratio of approx 90dB at 10MHz frequency, signal phase and maximum of 4.75kΩ source output impedance at 10MHz. Optimum data obtained using Pspice® is used to demonstrate the high-bandwidth performance of the source.
根据乔西恩特的说法，乳腺组织的有趣特性大多存在于1兆赫兹以上的频率；因此，需要一个覆盖更高频率（即高于1兆赫兹）的宽带激励源。本研究的主要目标是建立一个可行的带宽包络，可用于设计一个在宽频带上具有低输出阻抗的恒定EIM电压源，以实现实际应用。激励源是生物阻抗测量系统的主要组件之一。在任何生物阻抗测量系统中，激励源既可以通过注入电流并测量产生的电压来实现，也可以通过施加电压并测量产生的电流来实现。本文描述了三种电压源架构，并基于它们的带宽比较，提出了一种差分电压控制电压源（VCVS），其可在宽频带（>15兆赫兹）上使用。本文描述了所设计的EIM电压源在不同负载条件和负载电容下的性能，报告了在10兆赫兹频率下约90分贝的信噪比、信号相位以及在10兆赫兹时4.75千欧的最大源输出阻抗。使用Pspice®获得的最佳数据用于证明该源的高带宽性能。
