Invention Grant
- Patent Title: Clock conditioner circuitry with improved holdover exit transient performance
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Application No.: US14956667Application Date: 2015-12-02
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Publication No.: US09680484B2Publication Date: 2017-06-13
- Inventor: Benyong Zhang , Anjin Du , Junqiang Shi
- Applicant: Texas Instruments Incorporated
- Applicant Address: US TX Dallas
- Assignee: TEXAS INSTRUMENTS INCORPORATED
- Current Assignee: TEXAS INSTRUMENTS INCORPORATED
- Current Assignee Address: US TX Dallas
- Agent Andrew Viger; Charles A. Brill; Frank D. Cimino
- Main IPC: H03L7/00
- IPC: H03L7/00 ; H03L7/095 ; G06F1/04 ; G06F1/12 ; H03L7/14 ; H03L7/183

Abstract:
Disclosed is a circuit, such as a clock conditioner, that provides an improved ability to exit from holdover operations, most notably during conditions where the clock signal inputs to a PLL of the clock conditioner are significantly out of phase. The circuit utilizes the PLL to generate output clocks based on a reference clock and a feedback clock. During holdover mode, the PLL is unlocked. When the reference clock becomes available and holdover mode can be exited, a holdover controller issues a reset signal that triggers a synchronization of the phases of the inputs to the PLL. The reset signal causes the feedback divider component that generates the feedback clock input to reset its phase and adjust its divide ratio for at least the first divide cycle after restart so that its next rising edge will be phase-aligned with the reference clock. Once the two inputs of the PLL phase detector are phase-aligned, the PLL is re-enabled and the PLL smoothly resumes normal operation.
Public/Granted literature
- US20160164532A1 CLOCK CONDITIONER CIRCUITRY WITH IMPROVED HOLDOVER EXIT TRANSIENT PERFORMANCE Public/Granted day:2016-06-09
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