Super Regenerative Oscillator Frequency Tuning With Offset Compensation
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Solution Overview
Problem
Super regenerative receivers face challenges in maintaining frequency stability due to periodic quenching, leading to frequency drift and degraded bit error rate performance, as existing phase locked loop methods are ineffective in continuously controlling the oscillator frequency during operation.
Innovation Solution
A frequency tuning apparatus that includes a frequency tuner and a compensator, using a mapping table and offset table to adjust the oscillation frequency of the super regenerative oscillator based on target information and compensate for capacitance errors, ensuring alignment with the actual resonant frequency of the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase locked loop (PLL) scheme is used to control the oscillator frequency before receiving data, then the frequency can be calibrated to the target frequency, but leakage current occurs at the charge pump node during SRR operation causing frequency drift
Solution Approach 1:
The patent performs frequency calibration using PLL before the super regenerative receiver operates, establishing the correct frequency setting in advance. The calibrated oscillator configuration is then maintained during actual data reception, avoiding the need for continuous PLL operation that would cause leakage current and frequency drift.
2Loss of energy
If the PLL is turned off during SRR operation to avoid leakage current, then frequency drift is prevented, but the frequency cannot be continuously controlled and may drift during operation
Solution Approach 1:
The system performs frequency calibration before operation and maintains the calibrated settings throughout SRR operation, achieving both low power consumption and frequency stability by avoiding continuous PLL operation while preventing drift through proper initial calibration.
3Use of energy by moving object
If a frequency control loop (FCL) is used for low power design, then power consumption is reduced and frequency drift does not occur during calibration, but frequency offset occurs between calibration mode and actual data reception
Solution Approach 1:
The patent introduces a frequency offset compensation mechanism that acts as an intermediary between the FCL calibration process and actual data reception. The system measures the frequency offset that occurs during operation and applies compensatory adjustments to align the oscillator frequency with the target frequency during data reception, thereby eliminating BER performance degradation.
4Productivity
If periodic quenching is performed in SRR, then the receiver operates efficiently, but the bias current of the oscillator varies periodically making continuous frequency control impossible
Solution Approach 1:
The system performs frequency calibration before the periodic quenching operation begins, establishing the correct frequency setting in advance. This preliminary calibration allows the oscillator to maintain accurate frequency throughout the periodic quenching cycles without requiring complex continuous control mechanisms during operation.
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 effectively compensates for frequency drift, minimizing bit error rate degradation by actively tuning and stabilizing the oscillation frequency, even during data reception, thus enhancing the performance of super regenerative receivers.
Implementation Method 1
The oscillator may include a capacitor having a capacitance configured to be tuned. The frequency tuner may be further configured to control a portion of the capacitor in response to a control signal for controlling the capacitor.
Implementation Method 2
The frequency compensator may be further configured to compensate for a capacitance of the oscillator based on a compensation signal extracted from the offset table in correspondence to the target frequency.
Implementation Method 3
The signal magnitude and the startup time of the oscillator are based on a power and a frequency of a signal received at an antenna and a resonant frequency of the oscillator.
Data Source
AI summary
A frequency tuning apparatus includes: a frequency tuner configured to tune an oscillation frequency of an oscillator based on target information extracted from a mapping table in correspondence to a target frequency, and oscillation information collected from the oscillator; and a frequency compensator configured to compensate for a compensation error between the tuned oscillation frequency and the target frequency based on an offset table.