Clock Oscillator POR Gating for Faster Stable Startup
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Solution Overview
Problem
The existing clock circuits in integrated systems face a challenge in quickly and stably starting up after power-up, leading to a longer settling time due to the need for simultaneous voltage stabilization across all nodes in the oscillator circuit, which is controlled by the Power-on Reset (POR) circuit.
Innovation Solution
A clock circuit design that includes an oscillator circuit and a power-on reset circuit, where the power-on reset circuit is connected directly to the loop oscillation module, allowing the current generating module's nodes to be gradually powered on during the power-up process, thus incorporating the setting time of the current generating module within the release time of the enable control signal, thereby accelerating the oscillator circuit's settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the POR circuit controls both the current generating module and the loop oscillation module simultaneously, then all nodes of the oscillator circuit can be stabilized, but the settling time becomes longer
Solution Approach 1:
The oscillator circuit is divided into two independent parts: the current generating module and the loop oscillation module. The POR circuit only controls the loop oscillation module, allowing the current generating module to be powered on independently and stabilize its nodes during the POR release period, thus reducing overall settling time while maintaining stability.
Solution Approach 2:
The current generating module is activated in advance during the power-on process before the POR circuit releases its control. This preliminary action allows the current generating module to complete its voltage stabilization at all nodes during the time the POR circuit is still active, so that when the POR releases, the current generating module is already stable and does not extend the overall settling time.
2Reliability
If all nodes of the oscillator circuit are stabilized simultaneously by the POR circuit, then the clock can be stable, but the power supply-up settling time is extended
Solution Approach 1:
The circuit is segmented such that the POR circuit's control scope is limited to only the loop oscillation module. The current generating module operates independently without POR control, allowing its nodes to stabilize during the POR release period. This segmentation enables the clock to become stable faster while maintaining reliability.
Solution Approach 2:
The POR circuit applies control only partially to the loop oscillation module rather than to the entire oscillator circuit. This partial action is sufficient to ensure clock stability because the current generating module's nodes are already stabilized by the time the POR releases, eliminating the need for POR control over the entire circuit and reducing settling time.
Data Source
AI summary
A clock circuit comprises an oscillator circuit and a power-on reset circuit, the oscillator circuit comprises a current generating module and a loop oscillation module connected together; the current generating module is used for outputting a control current to the loop oscillation module; the loop oscillation module is used for outputting an oscillation signal with a set frequency under action of the control current; and the power-on reset circuit is connected to the loop oscillation module and is used for providing an enabling control signal to the loop oscillation module after a power supply is powered on to the power-on reset circuit and the oscillator circuit.