Multi-Band PLL Oscillator Switching for Radar Interference Control

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Solution Overview

Problem

Radar devices face interference issues due to limited frequency variable width and difficulty in expanding frequency modulation, leading to erroneous recognition and determination, especially when using specific modulation systems, and struggle to adopt unique frequency change patterns effectively.

Innovation Solution

A PLL circuit with a multi-band control oscillator and band setting unit that allows selective switching of frequency bands, enabling a wider frequency variable width and unique frequency change patterns by generating a reference signal for radar systems, including transmitters and receivers, to prevent interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional voltage control oscillator is used in radar devices, then the device can operate with a simple structure, but the frequency variable width is limited and interference issues occur

Engineering Contradiction:

Improveoscillator structureVSAvoidfrequency variable width

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The oscillator is divided into multiple independent bands (first band, second band, third band, etc.), each capable of frequency modulation within its own range. This segmentation allows the system to achieve a wider overall frequency variable width by switching between bands while maintaining operational simplicity within each band.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-band oscillator serves multiple functions: it can operate in any individual band separately, switch between bands, and provide frequency modulation within each band. This multi-functionality resolves the contradiction by enabling wide frequency coverage without requiring a completely different oscillator architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If a single-band oscillator is used, then the device structure remains simple, but unique frequency change patterns cannot be adopted effectively

Engineering Contradiction:

Improveoscillator configurationVSAvoidfrequency change patterns

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The oscillator configuration is made dynamic by enabling selective switching between multiple bands based on operational requirements. This allows the system to adapt frequency change patterns dynamically - using gradual frequency changes within a band when needed, or switching between bands for more complex patterns - without increasing the basic device structure.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If frequency modulation is expanded in conventional oscillators, then more frequency ranges become available, but interference and erroneous recognition increase

Engineering Contradiction:

Improvefrequency modulation rangeVSAvoidtarget recognition accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

By segmenting the frequency range into separate bands, the system can modulate frequency within each band independently. This prevents interference issues that arise from continuous wideband modulation while still providing expanded frequency coverage through band switching, thereby maintaining target recognition accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the operating parameter (frequency band) in discrete steps rather than continuous modulation. This parameter change approach allows expanded frequency range while avoiding the interference and erroneous recognition problems associated with continuous wideband frequency modulation.

Inventive Principle:

Principle #35Parameter changes

4Speed

If the frequency band is switched rapidly, then the response time improves, but the PLL circuit cannot properly lock and frequency accuracy deteriorates

Engineering Contradiction:

Improveband switching speedVSAvoidfrequency accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The control method performs preliminary actions by predicting when band switching should occur and preparing the switching timing in advance. This allows the system to switch bands at optimal moments when the radar is between frequency modulation cycles, ensuring both rapid response and proper PLL locking for frequency accuracy.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10536154B2PLL circuit for radar

Publication Date: 2020.01.14 DENSO CORP

AI summary

In a PLL circuit, a multi-band control oscillator includes multiple bands gradually increasing or decreasing a frequency in accordance with a control signal and being separated from each other, is capable of selectively switching one band among the multiple bands, and generates a signal of a frequency corresponding to the control signal in the band that is switched as a reference signal. A band setting unit sets the band of the multi-band control oscillator. The band setting unit sets the band for a present or subsequent time after a control command generator finishes outputting the control command to gradually increase or decrease from a previous start frequency to a previous stop frequency and before the control command generator starts outputting the control command to gradually increase or decrease from a present start frequency.