The development of electrochemical impedance spectroscopy method in the field of high-frequency signals is proposed using an amplitude-phase approach to analyze the parameters of various biological sensors. Unlike the standard high-frequency analog electrochemical impedance spectroscopy systems interfaces based on quadrature demodulation, the use of peak and phase detectors allows improving the basic metrological parameters, as well as simplifying the analog interface with a wide bandwidth of the biological sensor interrogation signal. The circuit design of the phase detector, as part of the general system, is considered on the components of the technological process TSMC 0.35um SiGe. The key feature of this block is the maximum speed due to the rejection of feedbacks. A large range of output voltages and a low speed of their change allow the use of standard analog input modules for inputting phase detector signals to a computer for subsequent digital processing. The final accuracy of biological sensor signal phase detection is maintained at an acceptable level due to the introduction of additional elements in the basic circuit and the digital algorithms presented in the work. The shown variant of carrying out the correction has immunity to nonlinearities of the output characteristic of phase detection for large phase deviations of the signal of the biological sensor. The process technology used in the design is classified as economical, which makes it possible to potentially reduce the electrochemical impedance spectroscopy systems cost of production and introduction of a mass application.
Keywords: biological sensor; impedance spectroscopy; phase detector; quadrature representation of a signal, digital correction, algorithm of data processing, SiGe-technology, system on chip, microwave range, analog interface