Wideband DAC Circuit Using Frequency-Band Partitioning to Cut Spurs
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Solution Overview
Problem
Existing methods for combining multiple digital-to-analog converters (DACs) to expand sample rate suffer from inaccuracies, errors in sample positioning, and unbalanced gain, leading to interfering signals known as spurs.
Innovation Solution
The proposed conversion circuitry separates a wideband digital signal into narrowband signals using filter circuits, which are then converted to analog signals by multiple DACs. These analog signals are combined in the frequency domain using an analog combiner circuit, avoiding the errors associated with time-interleaving methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-interleaving method is used to combine multiple DACs to expand sample rate, then productivity (sample rate expansion) is improved, but manufacturing precision (sample positioning accuracy and gain balance) deteriorates
Solution Approach 1:
The patent segments the wideband digital signal into multiple narrowband signals using filter circuits, with each signal assigned to a separate DAC channel. This segmentation approach avoids the time-interleaving method that causes positioning errors, while still achieving sample rate expansion through parallel processing of the segmented signals.
2Productivity
If time-interleaving method is used to combine multiple DACs, then productivity (sample rate expansion) is improved, but manufacturing precision (gain balance) deteriorates
Solution Approach 1:
By segmenting the signal in the frequency domain rather than time domain, each DAC operates on its own narrowband signal without requiring precise time synchronization and gain balancing. The filter circuits separate the signal spectrum into distinct bands that can be processed independently by each DAC channel.
3Productivity
If time-interleaving method is used to combine multiple DACs, then productivity (sample rate expansion) is improved, but object-generated harmful factors (spurs) increase
Solution Approach 1:
The patent extracts the problematic time-interleaving operation and replaces it with frequency-domain segmentation. By removing the time-interleaving mechanism that generates spurs, the system achieves sample rate expansion through parallel narrowband processing without introducing interfering signals into the output.
4Manufacturing precision
If frequency domain separation method is used to convert wideband digital signal, then manufacturing precision (signal accuracy) is improved, but device complexity (circuit structure) increases
Solution Approach 1:
The circuit uses filter circuits to segment the wideband signal into narrowband components, which are then processed by multiple DACs. This segmentation approach simplifies the overall architecture compared to high-speed single-channel DACs, as each component operates at lower frequencies with relaxed timing requirements.
Data Source
AI summary
An integrated circuit includes filter circuits that partition a wideband digital signal in a frequency domain to generate narrowband digital signals each having a different frequency band, digital-to-analog converter circuits that convert the narrowband digital signals to generate analog signals, and an analog combiner circuit that combines the analog signals into a single wideband analog signal.