整個半導體產業在數十年來就如同摩爾定律(Moore’s Law)所預測的一般，以倍速成長著。隨著製成技術的演進，各種半導體元件的尺寸面積都在不斷的縮小、速度不斷的加快，而隨之也增加了超大型積體電路的設計與應用範圍。在這劃時代的產業之中，關於元件可靠性的研究領域，一直扮演著極重要的角色。

基於以往對元件可靠度的分析，本研究將把可靠度分析繼續延伸到電路層次(circuit level)，並對於應用在展頻通訊(W-CDMA)系統下的混波器電路進行可靠度的探討。

由於混波器是半數位半類比的電路操作方式，RF Port的輸入是來自於天線接收後的訊號，正常約在-50dBm以下，如一般類比小訊號的操作。因為元件在這一級中偏壓在飽合區，容易出現的元件哀退機制為通道熱載子效應(CHE)；在LO Port部分，元件的操作則必須有如switch，類似於數位電路，因此LO Port的閘極輸入訊號為大訊號，容易出現的元件衰退機制則是F-N穿隧效應。

針對通道熱載子效應和F-N穿隧效應，以建構隨時間改變的元件子電路模型描述元件電性的衰退情況，並將之用於電路特性模擬，得到如轉換增益(CG)和線性度(IP3)隨時間改變的狀況，接著以W-CDMA通訊協定和超級非一次降頻架構的接收器系統(Super-Heterodyne Receiver Architecture)為基礎下，推算混波器所需達到的規格要求，得到混波器的可靠操作期限而完成電路可靠度設計及分析。

Based on the device reliability analysis , we extend the reliability analysis to the circuit level and predict the reliable operation time of the mixer circuit operated in W-CDMA System.

The mixer circuit functions in both analog and digital modes. The input signal to RF Port comes from the antenna and its magnitude is typically less than –50dBm. This makes the devices of RF Port operate in analog mode. The major degradation mechanism appeared in this stage is the Channel Hot Electron Effect, since device are biased in saturation region. For LO Port, transistors serve as a switch, similar to the digital operation. This condition makes transistor in LO Port suffer high gate stress. Therefore, the degradation mechanism appeared in the LO stage mainly due to F-N Stress.

Considering the Channel Hot Electron and Fowler-Nordheim Stress, a sub-circuit degradation model with operation time to predict the device degradation after suffering stress is proposed. Apply the model to the mixer circuit, simulate of change in Conversion Gain and IP3 of the mixer with operation time can be obtained. A brief discussion of the minimum requirement of the mixer circuit used in WCDMA & Super-Heterodyne Receiver Structure is proposed and the reliable operation lifetime extension can then be defined.

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