都卜勒超音波是目前臨床診斷上主要的血流量測工具之一。近年來，許多醫療設備包含超音波系統皆朝向小型化趨勢前進。有別於一般商用超音波系統，小型化流量計具有方便攜帶性及低價的優點。
本研究嘗試自製10MHz 脈衝式都卜勒超音波系統之接收端電路與信號處理模組。主要線路是使用高頻與高速電子元件，包括解調(Demodulation)、濾波(Filter)與取樣保持(Sample and Hold)等功能。
本系統使用基於ARM Cortex-M3( CM3)為內核之微控制器 (MCU)，其結合了低功耗、低成本、高整合跟簡易開發之優點，且內部提供2個類比數位轉換器(Analog Digital Converter, ADC)。因此類比都卜勒信號可經此ADC轉換成數位信號後由同一MCU進行即時信號處理運算及液晶顯示模組(Liquid Crystal Module, LCM)頻譜顯示，透過類比端與數位端之整合，使系統體積與成本減小並提高系統方便性。本研究利用信號產生器驗證MCU之數位信號處理功能並以血流仿體實驗驗證流速偵測效能，結果顯示所獲得之流速資訊可與實際流速設定呈線性比例關係。

Doppler ultrasound is one of the main blood flow measurement tools in clinical diagnosis. Miniaturization of medical devices including ultrasound systems has become an important trend due to the advantages of high portability and low-cost.
In this study, a 10MHz pulsed Doppler ultrasound system was developed for flow measurement. The primary circuits include high- frequency and high-speed electronic devices for demodulation, filtering, and sample-and-hold. In addition, the system uses an ARM Cortex-M3 based microcontroller (MCU) for real-time digital signal processing. The ARM-based MCU also offers two analog to digital converters(ADC) and has the advantages of low power and low cost. The analog Doppler signals were digitalized via the ADC on the same MCU for better integration and a Liquid Crystal Module (LCM) displays the Doppler spectrum.
Performance of the Doppler system was examined using blood flow phantom. Results indicate that the detected flow velocity is proportional to the actual flow velocity.

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