MIMO Radar IF Signal Combining to Cut ADC Count
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Solution Overview
Problem
Conventional FMCW MIMO radar systems face challenges in increasing angular resolution due to the need for multiple ADCs, which leads to increased IC chip area and interconnection complexity, as well as synchronization issues among ADCs, when trying to enhance the number of antenna elements.
Innovation Solution
The radar apparatus employs an offset frequency to differentiate the frequencies of local oscillation signals, allowing for the combination of downconverted receive signals into a single digital stream using a single or few ADCs, thereby reducing chip area and interconnections, and preventing synchronization problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of antenna elements is increased to improve angular resolution, then measurement precision is improved, but device complexity increases due to the need for more ADCs
Solution Approach 1:
Multiple downconverted receive signals from different antenna elements are merged into a single combined signal. The frequency downconverter combines the downconverted signals by adjusting their frequencies to occupy different positions on the frequency axis, allowing them to be processed by a single ADC instead of requiring separate ADCs for each antenna element.
Solution Approach 2:
The frequency parameter of the downconverted receive signals is changed by the frequency downconverter. Each signal's frequency is adjusted by a different offset frequency, causing them to occupy different positions on the frequency axis. This parameter change enables the signals to be combined and processed by a single ADC while maintaining the ability to distinguish between different antenna elements.
2Measurement precision
If multiple ADCs are used to process signals from multiple antenna elements, then measurement precision is improved, but the IC chip area increases
Solution Approach 1:
The patent merges the function of multiple ADCs into a single ADC by combining the downconverted receive signals before digital conversion. The frequency downconverter prepares the signals by assigning them different frequency positions, allowing a single ADC to process all antenna element signals simultaneously, thereby reducing the IC chip area required for ADC components and their interconnections.
3Measurement precision
If multiple ADCs are used to process signals from multiple antenna elements, then measurement precision is improved, but synchronization problems occur between ADCs
Solution Approach 1:
The patent eliminates synchronization problems between multiple ADCs by merging the signal processing path into a single ADC. The frequency downconverter combines all downconverted receive signals into one signal stream that is then processed by a single ADC, removing the need for complex synchronization mechanisms between multiple ADCs and improving system reliability.
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 enables the reduction of ADCs to a single unit, minimizing chip area and interconnections while maintaining effective target detection capabilities, thus enhancing the radar system's performance without increasing ADC complexity.
Implementation Method 1
a frequency downconverter configured to convert each of the RF receive signals into an in-phase (I)-channel IF signal and a quadrature (Q)-channel IF signal such that frequency bands of 2n IF signals for the RF receive signals are sequentially displaced by a predetermined offset frequency
Data Source
AI summary
Exemplary embodiments provide a radar apparatus having a plurality of antenna elements and enabling to reduce a number of ADCs as long as being allowable according to a bandwidth of the ADC, reduce a chip area occupied by the ADC and interconnections in an integrated circuit, and prevent a synchronization problem between the ADCs by sampling receive signals of multiple channels at once. Frequencies of local oscillation signals used for downconverting receive signals are set to be different from each other by an amount of an offset frequency, so that each of band-limited receive signals obtained through respective RF paths may occupy a different position on a frequency axis of a frequency domain. Downconverted receive signals are combined into a single signal and converted into a single digital signal stream, and a signal processing of the digital signal stream in a digital domain enables to obtain target data.