SAMPLING FRACTIONAL-N PHASE-LOCKED LOOP WITH FEEDBACK SPUR COMPENSATION

    公开(公告)号:US20240137029A1

    公开(公告)日:2024-04-25

    申请号:US17970477

    申请日:2022-10-19

    CPC classification number: H03L7/0992 H03L7/093 H03L2207/50

    Abstract: Embodiments herein relate to a sampling phase-locked loop (PLL) with a compensation circuit for reducing ripples due to the use of a fractional N divider. The compensation circuit includes a ripple amplifier and a ripple divider. The ripple amplifier receives an output voltage, Vmain, of a main sampling circuit of the PLL and amplifies its alternating current (AC) components. The amplified output voltage is provided to a ripple integrator which samples the minimum and maximum values to provide inputs to an operational amplifier (op amp). An output of the op amp is fed back to a digital-to-analog converter (DAC), which provides a corresponding compensation voltage, Vcomp. Vcomp is added to Vmain to provide a final output control voltage, Vctrl, to control a voltage-controlled oscillator (VCO) of the PLL.

    Fast start-up crystal oscillator
    13.
    发明授权

    公开(公告)号:US11205995B2

    公开(公告)日:2021-12-21

    申请号:US16833298

    申请日:2020-03-27

    Abstract: An apparatus injects a start clock to a crystal at the beginning to increase an overall start up speed of the crystal. The apparatus relies on an impedance change inside the crystal itself instead of searching for a synchronization on the yet small crystal oscillation. The apparatus includes an oscillator (separate from the crystal) to search for the crystal's resonance frequency by detecting the crystal's impedance change. Once the frequency of the oscillator matches the crystal's resonance, there is significant change in the crystal's impedance. Using that information, the apparatus can lock the oscillator frequency at the crystal resonance frequency and inject the clock with high efficiency.

    FAST START-UP CRYSTAL OSCILLATOR
    14.
    发明申请

    公开(公告)号:US20210305939A1

    公开(公告)日:2021-09-30

    申请号:US16833298

    申请日:2020-03-27

    Abstract: An apparatus injects a start clock to a crystal at the beginning to increase an overall start up speed of the crystal. The apparatus relies on an impedance change inside the crystal itself instead of searching for a synchronization on the yet small crystal oscillation. The apparatus includes an oscillator (separate from the crystal) to search for the crystal's resonance frequency by detecting the crystal's impedance change. Once the frequency of the oscillator matches the crystal's resonance, there is significant change in the crystal's impedance. Using that information, the apparatus can lock the oscillator frequency at the crystal resonance frequency and inject the clock with high efficiency.

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