Multi-Mode Digitally Controlled Oscillator for Step Size Trade-Offs
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Solution Overview
Problem
Existing digitally controlled oscillators (DCOs) are primarily adapted for a single wireless radio system standard, making it challenging to integrate multiple standards into a single device with varying frequency step size and phase noise performance requirements, such as GSM and UMTS, while also limiting modulation bandwidth and error vector magnitude (EVM) performance.
Innovation Solution
A digitally controlled oscillator device with a programmable capacitive element and a selection unit that allows for multiple modes, each with a predetermined frequency step size, enabling flexible generation of radio frequency signals suitable for different wireless radio system standards by adjusting capacitance and inductance using switchable capacitor devices and varactors, and controlling oscillating amplitude to meet diverse requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DCO is designed for GSM with fine frequency resolution (10 kHz step size), then the error vector magnitude performance is improved, but the modulation bandwidth is limited
Solution Approach 1:
The patent implements dynamic reconfiguration of the oscillator core by switching between different capacitive element arrangements (series/parallel connections) based on the selected wireless standard. This allows the frequency resolution and modulation bandwidth to be dynamically adjusted: for GSM, a fine resolution mode with 10 kHz steps is activated, while for UMTS, a broader bandwidth mode with 200 kHz steps is selected, optimizing performance for each standard.
2Device complexity
If multiple wireless radio system standards are integrated into one device with shared RF blocks, then device complexity is reduced, but the requirements for adapting to different frequency step sizes and phase noise performance become more stringent
Solution Approach 1:
The oscillator core is designed as a universal block that can serve multiple wireless standards (GSM, UMTS, EDGE) through reconfigurable capacitive elements. By implementing switchable capacitor devices and varactors that can be arranged in different configurations, a single oscillator core replaces what would traditionally require separate oscillators for each standard, reducing overall device complexity while maintaining standard-specific performance characteristics.
Solution Approach 2:
The patent changes key parameters of the oscillator core (capacitance values and connections) to adapt to different standards. For GSM, the capacitive elements are configured to provide 10 kHz frequency steps with specific phase noise characteristics, while for UMTS, the same elements are reconfigured to provide 200 kHz steps with different phase noise performance, allowing one hardware block to meet diverse standard requirements.
3Manufacturing precision
If the frequency step size is reduced for fine resolution, then the error vector magnitude is improved, but the achievable modulation bandwidth becomes smaller
Solution Approach 1:
The system dynamically adjusts the frequency step size based on the active wireless standard. For GSM where low EVM is critical, the oscillator is configured with fine frequency steps (10 kHz) to achieve the required 28 dB EVM performance. For UMTS where broader bandwidth is needed, the system switches to coarser steps (200 kHz) that support larger modulation bandwidths, thus optimizing the trade-off between precision and speed for each standard's specific requirements.
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 solution allows for efficient generation of radio frequency signals that meet the specific requirements of multiple wireless standards, such as GSM and UMTS, by providing adjustable frequency step sizes and improved phase noise performance, thereby enhancing modulation bandwidth and error vector magnitude (EVM) while reducing the need for separate radio frequency blocks.
Implementation Method 1
The oscillator core comprises an inductive element and a first capacitive element which is frequency determining and programmable
Data Source
AI summary
A digitally controlled oscillator device includes a programming input, a selection input and an oscillator core with a first capacitive element which is frequency determining and programmable. The first capacitive element is coupled to the programming input that receives a first data word by which an oscillating frequency of the oscillator device is programmed with a predetermined frequency step size. The oscillator device further includes a selection unit for selecting a mode which is coupled to the selection input that receives a mode selection signal. The mode is selectable from a plurality of modes depending on the mode selection signal and each mode from the plurality of modes is characterized by a predetermined frequency step size. The digitally controlled oscillator device also includes a deattenuation amplifier.