Frequency Estimation Signal Generation With Harmonic Suppression
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Solution Overview
Problem
Conventional methods for monitoring the frequency of a Voltage Controlled Oscillator (VCO) output in FMCW automotive radar systems require complex high-order analogue filters to suppress harmonics, which are difficult and costly to implement in CMOS technology, especially due to stringent accuracy requirements.
Innovation Solution
A frequency estimation system that includes a frequency estimation signal generator, analogue-to-digital converter, and digital signal processing circuit, utilizing a counter and continuous waveform generator to generate a sinusoidal waveform with suppressed harmonics, allowing for low-order filtering and integration in CMOS technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional frequency monitoring approach using a clock divider is used, then the frequency can be monitored, but complex high-order analogue filters are required to suppress harmonics
Solution Approach 1:
The patent replaces the mechanical/analog filtering system with a digital signal processing system. Instead of using complex high-order analog filters to suppress harmonics, the invention uses a Numerical Oscillator and Digital Signal Processing circuit to generate reference frequencies and perform digital correlation analysis, thereby eliminating the need for complex analog filtering while maintaining frequency monitoring accuracy.
Solution Approach 2:
The patent introduces a Numerical Oscillator as an intermediary component that generates reference frequencies based on the input signal. This intermediary allows the system to compare the input frequency against generated reference frequencies through digital processing, avoiding the direct need for complex analog filtering of harmonic components.
2Measurement precision
If high-order analogue filters are used to suppress harmonics, then frequency accuracy is improved, but manufacturing cost and difficulty increase
Solution Approach 1:
The patent substitutes complex analog filter manufacturing with digital circuit implementation. The frequency monitoring function is achieved through digital signal processing using a Numerical Oscillator and correlation analysis, which can be implemented using standard CMOS digital logic cells rather than requiring precision analog filter fabrication.
Solution Approach 2:
The patent changes the operating parameters from analog frequency domain filtering to digital time-domain correlation analysis. By using a Numerical Oscillator to generate reference signals and performing digital multiplication and integration, the system achieves high frequency measurement accuracy without requiring precision analog filter components.
3Object-generated harmful factors
If complex high-order analogue filters are implemented, then harmonic suppression is sufficient, but integration in CMOS technology becomes difficult
Solution Approach 1:
The patent replaces the analog filter system with a fully digital implementation that can be seamlessly integrated into CMOS technology. The Numerical Oscillator generates reference frequencies digitally, and the correlation processing is performed using digital logic operations, eliminating the need for complex analog filter circuits that are difficult to integrate in standard CMOS processes.
4Ease of manufacture
If a simple low-order filter is used, then manufacturing is easier, but harmonic suppression is insufficient for accurate frequency estimation
Solution Approach 1:
The patent introduces a Numerical Oscillator as an intermediary that generates reference frequencies and enables digital correlation processing. This intermediary allows simple low-order analog filters to suffice while achieving high frequency estimation accuracy through the digital processing stage that correlates the input signal with the generated reference frequencies.
Solution Approach 2:
The patent substitutes the need for high-order analog filtering with digital signal processing. The simple low-order analog filter is followed by a digital correlation processor that uses a Numerical Oscillator to generate reference signals, performing the heavy lifting of harmonic rejection in the digital domain rather than requiring complex analog filtering.
Data Source
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AI summary
A frequency estimation signal generator component arranged to receive an input frequency signal and to generate therefrom a frequency estimation signal. The frequency estimation signal generator component comprises a counter component arranged to sequentially output a sequence of control signal patterns over a plurality of digital control signals under the control of an oscillating signal derived from the received input frequency signal terns. The frequency estimation signal generator further comprises a continuous waveform generator component arranged to receive the plurality of digital control signals and a weighted analogue signal for each of the received digital control signals, and to output a continuous waveform signal comprising a sum of the weighted analogue signals for which the corresponding digital control signals comprise an asserted logical state. The frequency conversion component is arranged to derive the frequency estimation signal from the continuous waveform signal output by the continuous waveform generator component