PLL Voltage-Conversion Circuit for Wider Frequency Range Reliability
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Solution Overview
Problem
Existing PLL circuits face reliability issues due to the limited power supply range, which restricts the frequency range of the output signal and can lead to time-dependent dielectric breakdown in MOS transistors.
Innovation Solution
A PLL circuit design that includes a voltage-converting circuit with high withstand voltage transistors, allowing a larger power supply range than the voltage-controlled oscillator, thereby increasing the voltage applied to the oscillator and enhancing the output frequency without compromising reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power supply voltage to the charge pump is increased to expand the frequency range, then the output frequency range of the PLL circuit is increased, but the reliability of the charge pump deteriorates due to voltage exceeding withstand voltage
Solution Approach 1:
The power supply system is segmented into two independent parts: the charge pump operates at a lower, safe voltage (e.g., 1.2V) to ensure reliability, while the voltage-converting circuit operates at a higher voltage (e.g., 3.3V) to enable frequency expansion. This segmentation allows each component to operate within its safe voltage range while achieving the overall goal of extended frequency range.
Solution Approach 2:
The voltage-converting circuit acts as an intermediary between the charge pump and the voltage-controlled oscillator. It converts the lower voltage from the charge pump to a higher voltage suitable for the VCO, enabling frequency expansion without exposing the charge pump to excessive voltage that would compromise its reliability.
2Productivity
If a voltage-converting circuit with larger power supply range is introduced, then the output frequency is increased, but the device complexity increases
Solution Approach 1:
The voltage-converting circuit changes the voltage parameter from a lower level (charge pump output) to a higher level (VCO input). By controlling the conversion ratio and operating points, the circuit achieves frequency expansion while managing complexity through parameter optimization rather than structural complexity.
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
The design increases the output frequency of the PLL circuit while maintaining reliability by using high withstand voltage transistors in the voltage-converting circuit, allowing for higher voltage application to the oscillator, thus extending the life of MOS transistors and preventing dielectric breakdown.
Implementation Method 1
a voltage-converting circuit configured to convert a voltage from the charge pump and apply the converted voltage to the voltage-controlled oscillator
Implementation Method 2
a voltage-controlled oscillator including an oscillation portion
Data Source
AI summary
A PLL circuit includes: a charge pump; a voltage-controlled oscillator including an oscillation portion; and a voltage-converting circuit configured to convert a voltage from the charge pump and apply the converted voltage to the voltage-controlled oscillator. The power supply range supplied to the voltage-converting circuit is larger than the power supply range supplied to the oscillation portion of the voltage-controlled oscillator.