全差動三角積分調變器應用於生醫音頻前端電路

Abstract

本論文使用了反相放大器取代一般全差動放大器，實現一個高動態範圍、低電壓、低面積且低功率的全差動三角積分調變器。由於電子心脈聽診器或是助聽器這類產品多是攜帶式且利用電池提供供應電源，所以低電壓、低面積與低功率消耗為主要的需求。 我們的架構中，利用反相放大器搭配由相位產生器生成的四個互不相重疊相位進行切換，分別處理差動訊號。利用取樣保持電路將積分器訊號分別保存在電容之中，最後使用動態比較器及閂對差動輸出訊號作比較。 此晶片使用TSMC 0.18μm 製程來實現，晶片面積包含腳位約0.35mm2，達到低面積的需求。預定使用一般的電池提供供應電源約1.2V，設定電路的取樣頻率約為2.56MHz，系統訊號頻寬20kHz。可以得到其動態範圍93dB，最高SNR 約87dB，最高SNDR 約81dB，消耗功率約141μW。

In this thesis, we use inverter amplifiers to replace fully differential ones to implement a high dynamic range fully differential sigma delta modulator. Because the electron stethoscope and hearing aids are portable and using batteries to provide supply voltage, low-voltage and low power consumption are the key design consideration. In our structure, we use tri-state inverter amplifiers and four nonoverlapping phases to deal with the differential input signals. A sample and hold circuit used to separate the differential output signal of the integrator. Finally, we use a dynamic comparator and latch to compose the quantizer. This chip is designed in TSMC 0.18μm CMOS process, and the chip area is about 0.35mm2. Our design is in the biomedical audio frequency, from 20Hz to 20 kHz. The power supply voltage is 1.2V, and the sampling frequency is 2.56MHz. The sigma delta modulator has a SNR of 87dB, a SNDR of 81dB, a dynamic range of 93dB. It consumes 144.36μW of power.