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Subject: search.filters.subject.Analog circuit design

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    Linear variable differential transformer temperature compensation technique
    (2018-01-01)
    Petchmaneelumka, Wandee
    ;
    Mano, Pitsini
    ;
    Riewruja, Vanchai
    A feedback technique to compensate for the temperature effect on the output signal of the linear variable differential transformer (LVDT) without losing the sensitivity is presented in this paper. The proposed technique is based on the use of a voltage-controlled amplifier to scale the amplitude of the excitation signal for temperature compensation. The proposed feedback technique provides the proportional-plus-integral control action to minimize the error caused by the temperature variation. The proportional-plus-integral action is realized using the integral scheme in the proposed technique. The peak amplitude of the LVDT output signal is sampled by the sample-and-hold circuit (SHC) to obtain the feedback and displacement signals, where the control signal of the SHC is provided by the LVDT output signal. The proposed LVDT temperature compensation technique is emphasized in terms of simple configuration and low cost. Note that the proposed technique is suitable for signal conditioners embedded in smart sensors and smart materials. The performance of the proposed technique is confirmed by experimental implementation using commercially available devices. The maximum error of the core displacement signal can be reduced from 6.52% for the uncompensated scheme to 0.098% for the compensated scheme at the ambient temperature of 70 °C.
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    FTFN with variable current gain
    (2001-12-01)
    Tangsrirat, Worapong
    ;
    Unhavanich, Sumalee
    ;
    Dumawipata, Teerasilapa
    ;
    Surakampontorn, Wanlop
    This paper proposes a circuit configuration for the realization of a four-terminal floating nullor (FTFN) with electronically tunable current gain. It mainly consists of an op amp in input together with two complementary current mirrors with controlled gain and two standard improved Wilson current mirrors. The validity of the performance of the scheme is verified through PSPICE simulation results. Some example applications in the design of the proposed tunable FTFN as a tunable active element show that the circuit properties can be varied by electronic means are also included.