Papers by Keyword: Negative Impedance

Abstract: This paper describes a current mode filter using two current feedback amplifiers (CFA's). One CFA is used to simulate a negative resistor. The proposed circuit is very useful for low as well as high frequency applications. Circuit is simple and canonic. The use of grounded capacitors in the design make it suitable for implementation in CMOS technology.

Abstract: Piezoelectric transducer with negative impedance matching circuit is put forward to enhance its performance in broadband frequencies. The typical multi-physics problem is coupled with sound wave equations, structure stress-strain equations, piezoelectric constitutive equations and electric ordinary equations, and it is analyzed with FEM in detail. Frequency response characteristics are simulated when shunted with negative-impedance in series. When proper negative synthesized elements are connected, the performance of low frequencies and bandwidth are enhanced obviously.

Abstract: Piezoelectric acoustic sensor with negative impedance matching circuit is put forward to enhance its sensitivity at low frequencies. The multi-physics problem coupled with sound wave equations, structure stress-strain equations, piezoelectric constitutive equations and electric ordinary equations is analyzed with FEM in detail. Frequency response characteristics are simulated when shunted with negative-capacitance, resistance in series. Sensitivity is obtained from 1kHz to 5kHz. When used proper electrical elements, the sensitivity of the piezoelectric sensor can even exceed that of no matching circuit over 2 factors in broad band.

Abstract: Piezoelectric material shunted with negative capacitance can be used to insulate sound theoretically. But sound insulation of the system is limited by many factors. The dielectric and mechanical loss of the piezoelectric system deteriorate seriously the ability at some frequencies. According to the ideal electric elements formulas, the capacitance has imaginary part because of the loss. It has important influence on sound insulation ability. If a series resistance is introduced into the shunting circuit to form the imaginary part to compensate the loss, it is dependent on frequency. Sound insulation would be increased only in narrow band, and at some frequencies the system with the shunting circuit even becomes unstable.