Radar Chirp Generation Using Phase DAC and Frequency Multiplication
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Solution Overview
Problem
Radar systems face challenges in generating wideband and fast chirp signals due to the complexity and power consumption requirements, particularly in multi-input, multi-output (MIMO) systems, where tight phase alignment between transmitters and receivers is crucial for accuracy but difficult to achieve with existing PLL-based and DAC-based architectures.
Innovation Solution
The use of a phase digital-to-analog converter (DAC) that modulates the digital input to produce a phase-modulated analog signal, operating on a fixed frequency, which is then frequency multiplied to generate the desired chirp signal, reducing bandwidth and memory requirements and enabling flexible and efficient chirp generation across multiple transmitters and receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PLL-based architecture is used for chirp generation, then phase alignment can be achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the phase alignment function from the complex PLL architecture and implements it through a simplified direct digital synthesis (DDS) approach. The DDS generator produces chirp signals with predetermined phase relationships directly, eliminating the need for complex PLL circuits while maintaining phase coherence across multiple transmit and receive channels.
Solution Approach 2:
The patent implements a universal chirp generation architecture that can support multiple modulation schemes (linear chirp, quadratic chirp, etc.) and different MIMO configurations through a single DDS-based platform. This universal design eliminates the need for separate PLL circuits for each channel and modulation type, reducing overall system complexity.
2Productivity
If DAC-based architecture is used for chirp generation, then chirp signals can be generated, but bandwidth requirements and memory requirements increase
Solution Approach 1:
The patent pre-calculates and stores chirp signal parameters (phase, frequency, amplitude) in lookup tables within the DDS generator. This preliminary preparation allows the system to generate complex chirp signals with limited bandwidth by retrieving and combining pre-computed values, rather than requiring high-bandwidth real-time computation.
Solution Approach 2:
The patent transforms the chirp generation problem from the time domain to the frequency domain using DDS techniques. By generating chirp signals through phase accumulation and lookup tables in the digital domain, the system achieves efficient bandwidth utilization without requiring high-speed DACs, effectively moving the complexity from the analog bandwidth domain to the digital processing domain.
3Measurement precision
If tight phase alignment is implemented in MIMO systems, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges the phase alignment function into the central DDS generator, which produces all chirp signals for multiple transmit channels with predetermined phase relationships. This consolidation eliminates the need for separate phase alignment circuits in each transmit/receive module, achieving tight phase alignment while reducing overall device complexity.
Solution Approach 2:
The patent achieves phase alignment by dynamically adjusting digital parameters (phase offset, frequency offset) within the DDS generator rather than using complex analog phase alignment circuits. This parameter-based approach allows precise control of phase relationships between multiple channels through simple digital modifications, improving measurement precision without increasing hardware complexity.
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
This approach allows for efficient wideband and fast chirp generation with reduced power consumption and physical area requirements, enabling orthogonal modulation and improved radar system efficiency, including the ability to support different modulation schemes without architectural changes.
Implementation Method 1
a phase digital-to-analog converter (DAC) to convert a digital input that specifies at least one of a phase modulation or a frequency modulation into a phase modulated analog output
Implementation Method 2
a frequency multiplier to frequency multiply the phase modulated output centered on the intermediate frequency by a multiplication factor to generate a chirp signal
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture for wideband and fast chirp generation for radar systems are disclosed herein. An example apparatus includes a phase digital-to-analog converter to convert a digital input that specifies at least one of a phase modulation or a frequency modulation into an analog output, and to generate a phase modulated output centered on an intermediate frequency. The example apparatus also includes a frequency multiplier to frequency multiply the phase modulated output centered on the intermediate frequency by a multiplication factor to generate a chirp signal.