Chivapreecha, Sorawat

Loading...
Thumbnail Image
Preferred name
Chivapreecha, Sorawat
Alternative Name
Chivapreecha, S.
Chivapreecha, Sorwat
Main Affiliation
Email
sorawat.ch@kmitl.ac.th

Settings

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Continuously Tunable Frequency and Phase Biquad Oscillator
    (2026-05-01)
    Chivapreecha, Sorawat
    ;
    Suwannawach, Piyapan
    This paper presents an improvement to the performance of a biquad oscillator, which is a recursive oscillator known for its excellent long-term stability. However, a significant limitation is that the oscillation frequency cannot be changed while the system is operating. Directly changing the frequency during operation causes the amplitude of the generated signal to vary significantly, either increasing or decreasing. A zero-input response analysis is used to understand the cause of this problem and to develop a solution that allows the amplitude of the generated signal to remain constant even when the oscillation frequency is changed during operation. In addition, this paper presents a method for controlling the phase of the generated signal by using a 1st-order IIR phase shifter structure. The proposed structure is specifically designed to allow the phase of the signal at the oscillation frequency to be adjusted continuously and independently of the frequency parameter. This integrated oscillator enables real-time, independent control of both signal frequency and phase without amplitude drift, making it suitable for applications requiring precise and dynamic signal synthesis.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Amplitude Stabilization of Frequency-Tunable Biquad Digital Oscillator Using Zero-Input Response Analysis
    (2025-01-01)
    Chivapreecha, Sorawat
    ;
    Suwannawach, Piyapan
    ;
    Sato, Tomoaki
    This paper presents an analysis of the biquad digital oscillator, which leads to design improvements in the online oscillating frequency adjustment capabilities. The requirements for signal generation in a digital oscillator without input comprise the initial conditions as well as the coefficients, which are constants. The coefficient of biquad oscillator can be modified to be a tuning parameter for changing the oscillating frequency by the users. Although the frequency of the oscillating signal can be changed as desired, however, while the system is operating, the inconsistency of the changed coefficient with the initial conditions that emerge from the retained prior states causes the signal amplitude to lose its stability. The zero-input response of a system could be theoretically examined to identify and understand this behavior. Moreover, the issue of amplitude stabilization can be looked into and resolved with the use of the zero-input response analysis develop to an improvement, which results in maintaining the amplitude of the oscillating signal after the frequency change.