This paper presents two methods to optimize LoRa (Low-Power Long-Range) devices so that implementing multiplier-less pulse shaping filters is more economical. Basic chirp waveforms can be generated more efficiently using the method of chirp segmentation so that only a quarter of the samples needs to be stored in the ROM. Quantization can also be applied to the basic chirp samples in order to reduce the number of unique input values to the filter, which in turn reduces the size of the lookup table for multiplier-less filter implementation. Various tests were performed on a simulated LoRa system in order to evaluate the impact of the quantization error on the system performance. By examining the occupied bandwidth, fast Fourier transform used for symbol demodulation, and bit-error rates, it is shown that even performing a high level of quantization does not cause significant performance degradation. Therefore, the memory requirements of LoRa devices can be significantly reduced by using the methods of chirp segmentation and quantization so as to improve the feasibility of implementing multiplier-less filters in LoRa devices.
This paper describes the development and combination of monolithic radiation hardened linear macrocells.These are used as replacements for hybridized bipolar SSI (Small Scale Integration) linear microcircuits, discrete semiconductors and passive devices, at low technical, schedule and cost risk. The silicon technology used in the fabrication of such circuits is conventional; however, the approach develops achievable next generation design and fabrication techniques for producing radiation hardened linear microcircuits at reduced cost with high reliability. The paper discusses the selected technology, process, design approach, testability and testing implications, improvements in yield and reliability and the post radiation performance obtained by the semicustom macrocell approach at the device and cell level.
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