Digitally Controlled Oscillator Capacitance Matrix for Fine Frequency Tuning
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Solution Overview
Problem
Increasing the number of control bits and variable capacitance elements in digitally controlled oscillators to widen the oscillation frequency range results in increased occupation area and parasitic capacitance of control lines, making it difficult to maintain a small and constant frequency change with respect to a unit control signal.
Innovation Solution
The configuration of a digitally controlled oscillator with a variable capacitance part comprising a first and second element group, where the second element group includes 32x32 variable capacitance elements connected in a matrix, with switching elements and control lines that allow for discrete capacitance changes, reducing the number of control lines and parasitic capacitance, enabling finer frequency adjustments within a limited space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of control bits and variable capacitance elements is increased to widen the oscillation frequency range, then the frequency tuning range is improved, but the occupation area and parasitic capacitance of control lines increase
Solution Approach 1:
The patent applies binary-coded control signals where 5 control bits can address 32 variable capacitance elements (2^5 = 32). This dimensional encoding approach allows the system to control a larger number of capacitance elements without proportionally increasing the physical space required for control lines, effectively resolving the contradiction between frequency range expansion and control line area occupation.
2Adaptability or versatility
If the number of control bits and variable capacitance elements is increased to widen the oscillation frequency range, then the frequency tuning range is improved, but the parasitic capacitance of control lines increases
Solution Approach 1:
By implementing binary-coded control where 5 bits control 32 capacitance elements, the patent reduces the control signal complexity. This encoding method minimizes the parasitic capacitance impact by efficiently utilizing control lines, allowing frequency range expansion without proportional increase in harmful parasitic effects.
3Measurement precision
If the number of variable capacitance elements is increased, then the frequency resolution is improved, but the occupation area increases
Solution Approach 1:
The patent uses binary-coded control signals to address 32 variable capacitance elements using only 5 control bits. This dimensional encoding allows high-frequency resolution with fine granularity while keeping the control infrastructure compact, thereby achieving improved frequency resolution without proportional increase in occupation area.
4Measurement precision
If the number of control bits is increased, then the frequency control precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements a binary-coded control scheme where 5 control bits can selectively activate 32 variable capacitance elements. This encoding approach achieves precise frequency control by combining a moderate number of control bits with multiple capacitance elements, avoiding the need for an excessive number of control lines while maintaining high control precision.
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 configuration allows for stable and precise oscillation frequency control, reducing the number of control lines and parasitic capacitance, making it easier to increase the number of capacitance elements in a limited space while maintaining small frequency changes with respect to unit control signals, thus enhancing the frequency synthesizer's performance.
Implementation Method 1
a variable capacitance part including a first element group and a second element group, wherein each of the first element group and the second element group includes a plurality of variable capacitance elements
Implementation Method 2
A digitally controlled oscillator includes an inductor and a plurality of variable capacitance elements connected in parallel and is generally configured as an LC oscillation circuit. The digitally controlled oscillator is oscillated at a predetermined frequency by controlling each of the variable capacitance elements to either a high capacitance value or a low capacitance value
Data Source
AI summary
A semiconductor device according to the present embodiment includes a plurality of switching elements and a plurality of variable capacitance elements. The switching elements are switching elements connected in series between a first control terminal and a second control terminal and plural types of capacitance control signals can be supplied to the first control terminal and the second control terminal. The variable capacitance elements have capacitance control terminals connected to corresponding one ends of the switching elements, respectively.