Harmonic-Mixing Waveform Generator for Higher DAC Bandwidth
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Solution Overview
Problem
Conventional waveform generators face limitations in bandwidth due to digital-to-analog converter (DAC) constraints, leading to increased complexity and cost, as well as noise degradation in signal-to-noise ratio (SNR) when attempting to achieve higher bandwidths.
Innovation Solution
The use of harmonic mixing to increase the sample rate and usable bandwidth of analog output signals by splitting digital input signals into multiple paths, digitally mixing with harmonic signals, and then combining them to achieve a higher effective sample rate without the need for multiple DAC channels, thereby improving SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If synchronous time interleaving is used to achieve higher DAC sample rate, then the effective sample rate is multiplied, but a high bandwidth active combiner is needed which increases system complexity and cost
Solution Approach 1:
The patent introduces an asynchronous time-interleaved waveform generator as an intermediary system that uses multiple DACs with different sample rates and timing characteristics. Instead of requiring precise synchronous operation and high-bandwidth active combiners, the system uses asynchronous operation with a composite waveform generator that combines outputs from multiple DACs operating independently, thereby reducing the bandwidth requirements of the combiner and overall system complexity.
Solution Approach 2:
The system dynamically adjusts the operation of multiple DACs with different sample rates and timing characteristics. Rather than requiring all DACs to operate synchronously at the same rate, the system allows each DAC to operate at its own optimal rate and uses dynamic buffering and interleaving to combine their outputs, thereby achieving high effective sample rates without requiring high-bandwidth active combiners.
2Speed
If the number of DAC channels is increased to achieve higher bandwidth, then the bandwidth is improved, but the overall cost and complexity of the system increases
Solution Approach 1:
The patent changes the operating parameters of multiple DACs to achieve higher effective bandwidth. Instead of using multiple DACs operating at the same high sample rate, the system uses DACs operating at different sample rates and timing characteristics. The composite waveform generator interleaves these differently-parameterized outputs to achieve the desired effective bandwidth while keeping individual DAC requirements manageable and overall system complexity reduced.
Solution Approach 2:
The system segments the high-bandwidth waveform generation task across multiple DACs operating at different sample rates. Rather than requiring a single high-speed DAC or multiple identical high-speed DACs, the patent divides the waveform generation into segments handled by different DACs with different parameters, which are then combined by the composite waveform generator to produce the final high-bandwidth output.
3Speed
If conventional multiplexed time interleaved systems are used, then the DAC sample rate is limited by analog bandwidth, but achieving higher bandwidth requires many DAC channels which increases complexity
Solution Approach 1:
The patent implements dynamic asynchronous operation where multiple DACs can operate at different sample rates and timing characteristics rather than requiring synchronous operation. This dynamic approach allows the system to achieve higher effective sample rates without requiring complex synchronous multiplexing chips, as each DAC operates independently and the composite waveform generator handles the interleaving with appropriate buffering and timing adjustment.
Data Source
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Figure 3A~3B
AI summary
Waveforms generators include a splitter that splits a digital input signal into a number of split signals each having a split signal frequency bandwidth that is substantially similar to a digital input signal frequency bandwidth. The split signals are mixed with associated digital, harmonic signals to generate a number of digital, mixed signals, which are then converted to analog signals at an effective sample rate that is different from a first order harmonic signal of at least one of the digital, harmonic mixers. A number of analog, harmonic mixers mix the associated analog signals with associated analog, harmonic signals to generate mixed, analog signals. The mixed, analog signals are combined into an output signal having an output signal bandwidth that is greater than a bandwidth of at least one of the number of DACs.