Clock Interface Circuit Switching Between External and Internal Clocks
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Solution Overview
Problem
Existing electronic systems lack flexibility in controlling clock signals, requiring custom clock designs for different applications and often relying on external clock sources, which increases manufacturing costs and complexity.
Innovation Solution
A semiconductor die with a clock interface circuit that includes an oscillator and a comparator, allowing it to operate in multiple clock control modes based on the supply voltage level, enabling the generation of clock signals either from an input signal or an internal oscillator, thus providing flexibility in clock signal control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external clock sources are used, then clock signal control is achieved, but manufacturing costs and system complexity increase
Solution Approach 1:
The clock interface circuit is designed to perform multiple functions: it can operate as an external clock input interface, an internal oscillator, or a clock buffer depending on the configuration of the clock interface pin. This multi-functionality eliminates the need for separate external clock sources in many applications, reducing system complexity while maintaining clock control flexibility.
Solution Approach 2:
The semiconductor die includes an internal oscillator that can generate clock signals autonomously without requiring external clock sources. The clock interface circuit automatically detects the electrical characteristic of the clock interface pin and configures itself to operate in the appropriate mode, providing self-service capability that reduces manufacturing costs and system complexity.
2Adaptability or versatility
If custom clock designs are created for different applications, then specific application requirements are met, but manufacturing costs increase
Solution Approach 1:
A single clock interface circuit design can serve multiple applications by configuring the clock interface pin to different electrical characteristics. The circuit can operate in external clock mode, internal oscillator mode, or buffer mode, providing application-specific clock control without requiring custom designs for each application, thereby reducing manufacturing costs.
Solution Approach 2:
The clock interface circuit responds to changes in the electrical characteristic parameter of the clock interface pin (such as voltage level or impedance) to automatically configure its operation mode. This parameter-based configuration allows the same hardware design to adapt to different application requirements without physical customization, reducing manufacturing complexity and cost.
3Device complexity
If internal oscillators are used, then external clock sources are reduced, but clock signal frequency control flexibility may be limited
Solution Approach 1:
The clock interface circuit dynamically switches between operating modes based on the detected electrical characteristic of the clock interface pin. When configured for internal oscillator operation, the circuit can still provide frequency control flexibility through the oscillator design, while maintaining the ability to switch to external clock mode if frequency control flexibility is required, thus balancing component reduction with control flexibility.
Solution Approach 2:
The clock interface circuit provides universal functionality by supporting both internal oscillator operation and external clock input. This multi-functionality ensures that the internal oscillator can be used to reduce external components when appropriate, while the ability to accept external clocks maintains frequency control flexibility when needed, accommodating various application requirements with a single design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows the same semiconductor die to be used across various applications, reducing the need for custom clock designs and minimizing the reliance on external clock sources, while offering enhanced flexibility in tuning oscillation frequencies and reducing noise and jitter.
Implementation Method 1
a first comparator configured to control operation of the clock interface circuit in a selected clock control mode chosen from two or more clock control modes based on comparing an electrical characteristic of the first clock interface pin to a comparison threshold
Implementation Method 2
an oscillator configured to generate an oscillator signal
Implementation Method 3
the clock interface circuit being configured to generate the comparison threshold based on a voltage level of the supply voltage, VDD
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3
AI summary
Apparatus and methods for controlling a clock signal are provided. In certain embodiments, a semiconductor die includes a core circuit and a clock interface circuit that provides a clock signal to the core circuit. The clock interface circuit includes an oscillator for generating an oscillator signal, and a comparator for controlling operation of the clock interface circuit in a selected clock control mode based on comparing an electrical characteristic of the clock interface pin to a comparison threshold. The selected clock control mode is chosen from a first clock control mode in which the clock interface circuit generates the clock signal based on an input clock signal received on a clock interface pin, or a second clock control mode in which the clock interface circuit generates the clock signal based on the oscillator signal.