Digitally Controlled Oscillator Capacitance Layout for Low Spurious Noise
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Solution Overview
Problem
Existing digitally controlled oscillator devices face challenges in achieving high-resolution oscillation frequency setting and reducing noise away from the oscillation frequency, particularly in wireless communication systems, where the use of sigma delta modulators can increase power consumption and area, and require additional noise suppression components like SAW filters, which complicates system miniaturization and cost reduction.
Innovation Solution
A digitally controlled oscillator device is designed with first and second oscillation output nodes, coil elements, and capacitor units, including a negative resistance generating circuit, which allows for the realization of fractional capacitance without a sigma delta modulator, thereby reducing noise away from the oscillation frequency and achieving high-precision fractional capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sigma delta modulator is used to achieve fractional capacitance control, then oscillation frequency resolution is improved, but power consumption increases and area increases
Solution Approach 1:
The patent extracts and removes the sigma delta modulator from the oscillator system, replacing it with a direct fractional capacitance control mechanism using capacitor units. This eliminates the need for the complex modulator circuit while achieving the same fractional capacitance effect through direct digital control of capacitor switching, thereby reducing power consumption and area.
Solution Approach 2:
The patent replaces the mechanical/complex signal processing system (sigma delta modulator) with a simpler electronic control system that directly switches capacitor units based on digital control signals. This substitution achieves fractional capacitance control through direct electronic switching rather than through complex modulation and filtering, reducing both power consumption and circuit area.
2Measurement precision
If a sigma delta modulator is used to achieve fractional capacitance control, then oscillation frequency resolution is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the sigma delta modulator from the oscillator system, replacing it with a direct fractional capacitance control mechanism using capacitor units. This eliminates the need for the complex modulator circuit while achieving the same fractional capacitance effect through direct digital control of capacitor switching, thereby reducing power consumption and area.
Solution Approach 2:
The patent segments the capacitance control function into discrete capacitor units that can be independently switched. Instead of using a single complex modulator, the total capacitance is divided into multiple smaller capacitor units (CF0, CF1, CF2, etc.) that are controlled by separate control signals, allowing for precise fractional capacitance control through simple switching operations.
3Object-generated harmful factors
If noise suppression components like SAW filters are added, then noise away from oscillation frequency is reduced, but area increases and cost increases
Solution Approach 1:
The patent converts the potential harm of noise away from the oscillation frequency into a benefit by designing the capacitor control system to inherently minimize such noise. The direct digital control of capacitor units without sigma delta modulation eliminates the quantization noise and spurious signals that would otherwise require external filtering, turning the control mechanism itself into a noise-reduction solution.
Solution Approach 2:
The patent extracts and removes the need for external noise suppression components like SAW filters by implementing a control architecture that inherently produces clean spectral output. The direct capacitor switching mechanism avoids the noise-generating mechanisms of sigma delta modulation, eliminating the requirement for additional filtering hardware and reducing overall device area.
4Object-generated harmful factors
If SAW filters are added for noise suppression, then noise away from oscillation frequency is reduced, but system cost increases
Solution Approach 1:
The patent converts the potential harm of noise away from the oscillation frequency into a benefit by designing the capacitor control system to inherently minimize such noise. The direct digital control of capacitor units without sigma delta modulation eliminates the quantization noise and spurious signals that would otherwise require external filtering, turning the control mechanism itself into a noise-reduction solution.
Solution Approach 2:
The patent extracts and removes the need for external noise suppression components like SAW filters by implementing a control architecture that inherently produces clean spectral output. The direct capacitor switching mechanism avoids the noise-generating mechanisms of sigma delta modulation, eliminating the requirement for additional filtering hardware and reducing overall device area.
Data Source
AI summary
The present invention provides a digitally controlled oscillator device capable of reducing noise away from an oscillation frequency, and a high frequency signal processing device. Fractional capacitances are realized using a plurality of unitary capacitor units, for example. In one unitary capacitor unit, one ends of two types of capacitive elements are respectively coupled to oscillation output nodes. On the other hand, in the unitary capacitor units other than the one unitary capacitor unit, one ends of two types of capacitive elements are respectively coupled to a fixed voltage. The other ends of one capacitive elements in all the unitary capacitor units are coupled in common, and the other ends of other capacitive elements are also coupled in common. Turning on and off of respective switches in all the unitary capacitor units are controlled in common.