無線傳感器設計中功耗與性能的平衡

　　無論是電池供電，甚至能源消耗，無線傳感器設計需要仔細權衡電力需求和運營能力，以達到性能目標。對于工程師來說，轉化為精心挑選的MCUs和收發器能夠滿足嚴格的功率預算，可以在范圍和靈敏度不同無線網絡提供傳感器數據。本文將展示如何將這些設計目標，可以滿足使用一系列的MCU，收發器和集成解決方案供應商如AMS、EnOcean、集成、芯片技術，Silicon Labs、德克薩斯文書。

　　在其最基本的形式，一個無線傳感器包括主機單片機和無線收發，以及電源系統和一個模擬前端（AFE）不同的復雜性取決于應用（圖1）。對于設計師來說，既擴展范圍和無線傳感器的設計最大功率效率要求的超低功耗MCU和收音機仔細選擇。

　　Figure 1： In a wireless sensor， the MCU and transceiver are key components in determining power and communications performance. （Courtesy of Texas Instruments.）

　　Although active power consumption specifications quoted in datasheets may be sufficient in some cases， selection typically requires a broader look at device performance characteristics associated with the device‘s available low-power operating modes. For example， an MCU that specs out with slightly higher active power requirements than another might still provide superior overall power savings if it offers different options for low-power modes and if it includes features and characteristics that ensure maximum time spent in its lowest power modes.

　　That notion of heightened efficiency fuels a trend toward use of 16- and even 32-bit MCUs in applications long considered the sole domain of 8-bit MCUs. With their wider data paths， 16- and 32-bit MCUs offer greater code density that in many cases allows for more efficient code execution – translating to faster completion of tasks and a quicker return to low-power sleep modes.