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Subject: search.filters.subject.Frequency stability

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    A Sub-100ppm/∘C Temperature-Compensated High-Frequency CMOS Relaxation Oscillator
    (2016-01-01)
    Sakphrom, Siraporn
    ;
    Georgiou, Pantelis
    ;
    Thanachayanont, Apinunt
    A temperature-compensated high-frequency CMOS integrated relaxation oscillator with low frequency variations is presented. A current-controlled oscillator topology is employed with a resistive source-degenerated transconductor and a current comparator to achieve high oscillation frequency and low power dissipation. The proposed oscillator was designed with process parameters from a standard 0.35-μm CMOS technology and a 2.5-V single power supply voltage. At a nominal oscillation frequency of 21 MHz, the total power dissipation of the circuit was 201 μW. Post-layout simulation results showed that the frequency variations were less than 34.16ppm/∘C over a temperature range of -40 to +120∘C.
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    A high frequency stability of VCO with dual feedback loop
    (2005-12-01)
    Vibunjarone, Vichupong
    ;
    Prempraneerach, Yothin
    This paper is purposed to improve the high frequency stability of the voltage controlled oscillator (VCO) with dual feedback loop. The proposed of closed loop VCO (CLVCO) is composed of PI controller in the forward part and in the feedback part the phase locked loop is used instead of a frequency to voltage converter (FVC) for some advantages, there is no need for a large frequency division element (1/N) in the feedback part. The other advantages of phase-locked loop is used as the feedback element, the high frequency bandwidth of a closed loop VCO is possibly designed. The CLVCO can greatly improved VCO characteristic such as faster speed response as well as higher operation bandwidth, to minimize the effect of the VCO noise and the power supply variation and also obtain better linearity of VCO output. The experimental results confirm the validity of the proposed CLVCO. © 2005 SICE.
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    Improved noise reduction ability and frequency stability of VCO with external feedback loop
    (2005-12-01)
    Vibunjarone, Vichupong
    ;
    Prempraneerach, Yothin
    This paper presents the integrated circuit combined with PI controller and the frequency to voltage converter (FVC) acting as the feedback part to be a closed-loop VCO circuit (CLVCO). The PI controller is designed by symmetrical optimum for optimum output response so as to minimize the effect of VCO noise. This closed loop circuit can achieve good frequency stability as well as good noise suppression. The experimental results show that CLVCO is independent from power supply variation and the frequency stability due to the effect of VCO noise or voltage drift which is greatly improved. © 2005 SICE.
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    A new phase-locked loop system with the controllable output phase and the lock up time
    (2005-12-01)
    Vibunjarone, Vichupong
    ;
    Prempraneerach, Yothin
    This paper, we propose a new phase-locked loop (PLL) system with controllable the output phase independent from the output frequency and lock-up time. This PLL system has a dual control loop is described, the inner loop greatly improves VCO characteristic. The main loop is the heart of this PLL, which greatly improves the output frequency instability due to the external high frequency noise coupling to the input reference frequency. This main loop has the two control inputs, the first one achieves to control the output frequency of the VCO and the other one is used to control the output phase independently from the frequency output as well as the lock-up time which can be controlled for optimum output response by this input. The experimental results confirm the validity of the proposed phase-locked loop. © 2005 SICE.