Segmented DCO Capacitor Bank Calibration for Nonlinearity Compensation
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Solution Overview
Problem
LC-based digitally controlled oscillators (DCOs) with binary weighted capacitor banks suffer from non-linearity due to process variations, leading to phase errors in their frequency output, which existing technologies have not effectively addressed.
Innovation Solution
A segmentation superposition module is introduced to measure and compensate for non-linearity in the capacitor bank by generating compensation vectors that adjust the frequency control signal, allowing for precise activation of capacitors to achieve a desired output frequency, thereby reducing phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a binary weighted capacitor bank is used in an LC-based DCO, then the layout area is reduced and the design is more compact, but non-linearity occurs due to process variations leading to phase errors
Solution Approach 1:
The capacitor bank is divided into multiple segments or groups, where each segment corresponds to a specific bit weight. By segmenting the binary-weighted capacitors and applying individual calibration or compensation techniques to each segment, the patent reduces the impact of process variations on overall linearity while maintaining the compact layout benefits of binary weighting.
Solution Approach 2:
The patent employs calibration techniques that adjust the effective capacitance values through digital control, changing the electrical parameters to compensate for manufacturing variations. This allows the system to achieve better linearity by dynamically adjusting capacitor weights after fabrication, without altering the physical layout.
2Device complexity
If a binary weighted capacitor bank is used in an LC-based DCO, then the design complexity is reduced compared to thermal meter arrangements, but phase errors occur due to non-linearity
Solution Approach 1:
The patent implements preliminary calibration during the manufacturing or initialization process, where the actual capacitance values are measured and compensation values are pre-calculated and stored. This preliminary action ensures that phase accuracy is maintained during operation without requiring complex real-time correction circuits.
Solution Approach 2:
The patent incorporates feedback mechanisms where the actual output frequency or phase is measured and compared against the desired value, and the binary-weighted capacitor control signals are adjusted accordingly. This feedback loop compensates for non-linearity effects while maintaining the simplicity of the binary-weighted architecture.
3Area of stationary object
If binary weighting technique is used for capacitor tuning bank, then the layout is more compact, but non-linearity results in phase error in the DCO output
Solution Approach 1:
The patent transitions from a purely physical/dimensional approach to frequency control to a multi-dimensional solution that combines physical capacitor switching with digital compensation dimensions. By adding the digital calibration and compensation layer, the system achieves high frequency accuracy without sacrificing the compact physical layout of the binary-weighted capacitor bank.
Data Source
AI summary
Systems and methods for compensating a non-linearity of a digitally controlled oscillator (DCO) are presented. Data comprising a plurality of silicon measurements is received. Each silicon measurement in the plurality of silicon measurements is compared to an ideal value. Based on the comparing, a plurality of compensation vectors is generated. Each compensation vector comprises at least one silicon measurement. At least one frequency is adjusted based on a compensation vector in the plurality of compensation vectors. A digitally-controlled oscillator frequency is generated based on the adjusted at least one frequency.