集成的模擬前端，MCU簡(jiǎn)化能量收集無(wú)線傳感器節(jié)點(diǎn)的設(shè)計(jì)

　　能源收集已經(jīng)成為一種有效的方法來(lái)為監(jiān)測(cè)環(huán)境因素的無(wú)線傳感器節(jié)點(diǎn)供電。然而，對(duì)于傳感器子系統(tǒng)本身，工程師在構(gòu)建合適的解決方案時(shí)會(huì)面臨重大挑戰(zhàn)，增加了項(xiàng)目進(jìn)度的延遲。許多傳感器的設(shè)計(jì)，工程師可以利用低功耗的模擬前端（AFE）和專(zhuān)門(mén)的MCU IC制造商包括模擬設(shè)備，賽普拉斯半導(dǎo)體、芯片技術(shù)、德克薩斯文書(shū)，其中。

　　為了開(kāi)發(fā)傳感器系統(tǒng)，工程師們傳統(tǒng)上依靠手工構(gòu)建合適的信號(hào)鏈，結(jié)合運(yùn)算放大器、比較器和相關(guān)組件來(lái)可靠地收集傳感器數(shù)據(jù)。雖然從傳感器獲取信號(hào)的概念看似簡(jiǎn)單，工程師們發(fā)現(xiàn)自己面臨一長(zhǎng)串如傳感器驅(qū)動(dòng)和輸出的要求，實(shí)際問(wèn)題的采樣率，信號(hào)路徑校準(zhǔn)，性能，和傳感器診斷，在規(guī)定的功率預(yù)算。在信號(hào)路徑本身中，與元件匹配、偏置微調(diào)、電路板布局和附近噪聲源相關(guān)的挑戰(zhàn)增加了建立有效模擬信號(hào)通路的進(jìn)一步復(fù)雜問(wèn)題。

　　Signal requirements

　　Because sensor outputs can be very small signals， sensor signal paths typically require low-noise programmable gain amplifiers （PGAs） with extremely-low offset voltage， as well as low temperature and offset drifts to reduce the chance of introducing errors. In many cases， the common-mode voltage output of the sensor is much larger than the signal of interest， so some designs may require amplifiers with sufficiently high common-mode rejection ratios.

　　Due to the small sensor signals and overall sensitivity to noise， sensor signal paths also typically include design elements designed to limit the noise floor. These designs typically incorporate filters to limit the signal bandwidth and reduce noise contributions. In addition， chopper-stabilized amplifiers might be used to reduce errors from 1/f noise of the amplifiers. Finally， the use of a ΣΔ ADC with its oversampling conversion method helps reduce noise and associated noise-filtering requirements.