Spectral Shaping of Pseudorandom Binary Sequences
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Solution Overview
Problem
Existing methods for generating spectrally shaped pseudorandom binary sequences often increase circuit complexity due to digital filtering, which can convert single-bit signals into multi-bit signals, making them unsuitable for applications like chopping or requiring more complex components.
Innovation Solution
A digital filter with L filter branches, where one subset generates equal outputs and another subset generates inverted outputs, upsampling the original pseudorandom binary sequence by an integer factor L, allowing spectral shaping while maintaining the same bit length, enabling direct control of switches or use with low complexity components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital filtering is used to shape the spectrum of a pseudorandom binary sequence, then spectral shaping is achieved, but circuit complexity increases significantly
Solution Approach 1:
The digital filter is segmented into L filter branches, each processing a specific subset of samples. This segmentation allows the filter to operate at a lower effective complexity while achieving the same spectral shaping effect, as each branch handles only a portion of the signal processing task
Solution Approach 2:
The patent transforms the time-domain signal processing into a frequency-domain approach by using upsampling. The filter branches process different frequency components simultaneously, converting a complex time-domain filtering operation into a simpler frequency-domain operation that reduces circuit complexity
2Adaptability or versatility
If digital filtering converts a single-bit sequence to a multi-bit signal, then spectral shaping is achieved, but the signal becomes unsuitable for direct control applications
Solution Approach 1:
The patent merges the spectral shaping function with the signal format preservation function. By designing the filter branches to output binary signals that are either equal to or inverted versions of the input, the system combines spectral shaping with single-bit output generation, eliminating the need for separate conversion operations
Solution Approach 2:
Instead of converting a single-bit signal to multi-bit and then trying to convert back, the patent inverts the approach by designing filter branches that directly output single-bit signals. The inversion operation (outputting the negative of the input) is applied selectively to create the desired spectral shape while maintaining single-bit format
Data Source
AI summary
A pseudorandom binary sequence having a first sampling rate is generated. Based on the pseudorandom binary sequence, a digital filter generates a spectrally shaped pseudorandom binary sequence having a second sampling rate. The second sampling rate is equal to the first sampling rate multiplied by an integer upsampling factor of L>1. The digital filter includes L filter branches consisting of a first subset of one or more filter branches and a second subset of one or more filter branches. Each filter branch of the first subset generates a binary output which is equal to an input of the filter branch. Each filter branch of the second subset generates a binary output which is inverted with respect to an input of the filter branch.