適用於高速原子力顯微鏡的振幅偵測器

Abstract

原子力顯微術(AFM)已成為奈米級量測的重要工具，其對生物樣品具有高解析度成像，然而一般的原子力顯微術需要花幾分鐘成像，以至於無法觀察到生物系統的動態過程， 我們計畫發展快速成像的高速原子力顯微術，目前的系統進行成像時，震幅偵測器需要最多的時間，透過加速震幅偵測能有效的提高掃描速率，我們提出了一個使用離散元件實現的震幅偵測器，它能在一個輸入週期內偵測出震幅，我們量測到在輸入為1.5百萬赫茲的頻率下，它的延遲時間約為840奈秒，且可以在目前的系統中成功運作並比原本使用的震幅偵測器H2FLI更清楚成像，除此之外，我們使用聯電180奈米製程實現此電路，具有在半個輸入週期內偵測出震幅的能力，在布局後模擬中，延遲時間約為500奈秒，非線性誤差為1.56×10-5，達到10位元解析度且平均功率為0.93毫瓦。

Atomic force microscopy (AFM) has become the most important tool for characterizing the structures and mechanical properties of material surfaces on the scale of nanometers. It allows high-resolution imaging of biological samples in physiological solutions. However, it usually takes minutes to take an image with AFM. The functions of biological systems are produced through dynamic processes, which are too fast for AFM. We plan to develop high-speed AFM by speeding up the amplitude detection which takes the most time in our prototype system. We proposed an amplitude detector implemented with discrete components detects an amplitude with one input cycle. The latency is about 840ns as the input with 1.5MHz in measurement. And the circuit works on our AFM prototype successfully with the clearer image than Zurich Instrument H2FLI. In addition, we implement the circuit in UMC 180nm CMOS process, and the integrated circuit detects an amplitude with half input cycle. The latency is about 500ns and the nonlinear error is 1.56×10-5 smaller than 2-12. The circuit achieves 10-bit resolution and consumes 0.93mW power dissipation in our post-layout simulation.