摘要
在射頻接收機前端電路中，混頻器是一個重要的元件，其主要的工作原理為將前級的低雜訊放大器輸出之射頻訊號與壓控震盪器輸出之射頻震盪訊號進行混頻，進而將高頻訊號轉換成低頻提供給後級的數位電路使用。在RFIC電路的設計中，可以發現混頻器的線性度對於整個射頻接收前端電路是相當重要的。

在本論文中，學生提出數個射頻混頻電路應用在WiMAX以及LTE頻段，總共五個電路設計中可以分為兩個部份，第一個部分為基於一個雙頻共電流混頻器的核心架構下，做的一些特性改善的電路設計。而第二部分則是以系統的觀點來設計的兩個低功率高線性度的創新混頻器設計。第一部分包含以下三個電路設計:應用於WiMAX之主動式巴倫器輸入雙頻共電流混頻器、應用於WiMAX之主動式巴倫器輸出高增益雙頻混頻器、具線性補償機制之創新主動式巴倫器輸入雙頻混頻器。第二部分則包含以下兩個電路設計：應用於LTE系統之創新低功率高線性度相位轉移混頻器以及應用於WiMAX系統之高線性度低功率基極驅動混頻器。

在應用於WiMAX的主動式巴倫器輸入雙頻共電流混頻器中，學生使用了一主動式巴倫器架構當作雙頻共電流混頻核心架構的輸入級，由前級的加入抑制後級核心架構所產生的雜訊誤差，並且經由主動式巴倫器的特性提高了整體混頻器的增益表現。

在應用於WiMAX之主動式巴倫器輸出高增益雙頻混頻器中，延續先前的設計，為了降低差動輸出在量測上的誤差以及不方便，除了輸入主動式巴倫器輸入外，在輸出級又加入了一個雙端轉單端的主動式巴倫器輸出架構，而使得此混頻器設計成為一個特化的高增益混頻器架構。

在具線性補償機制之創新主動式巴倫器輸入雙頻混頻器中，由前兩個設計發現，主動式巴倫器的加入雖然可以使整體的增益上升，但卻會讓線性度相對的下降。因此，在這個電路設計中，學生加入了一個線性補償的機制使得整體的線性度在不影響增益的前提下有顯著的提升。

在應用於LTE系統之創新低功率高線性度相位轉移混頻器中，學生改善了一已發表之電路設計上的缺陷，進而成為一新的混頻架構設計。在此架構中，為了達到低消耗功率的目的，使用了一相移器輸入的架構，並省略了轉導級以降低電晶體的堆疊，此架構不僅降低了消耗功率並可以使線性度有顯著的提升。

在應用於WiMAX系統之高線性度低功率基極驅動混頻器中，學生除了省略轉導級外，改採用直接將射頻訊號輸入在基極端以追求更低的功率消耗及更高的線性度，而在輸入端加入了主動式巴倫器用以抵銷省略轉導級所造成的增益下降。

本篇論文之電路設計是以TSMC 0.18μm CMOS 製程之model進行模擬，並透過CIC申請下線，完成晶片之製作。

Abstract
In radio frequency receiver front-end, mixer is an important component. Mixer can mix the RF signal from low noise amplifier with voltage control oscillator than translate high frequency signal into low frequency signal for base-band system. In the course of design of the RFICs, it was found that its linearity performances are important for the performance of receiver.

In this thesis, several mixer designs using in WiMAX and LTE are presented. Those five circuit designs can divide into two parts. The first part is the improvement design based on a novel concurrent mixer core. It contains three circuits: The dual-band concurrent mixer with active balun for WiMAX applications, the high gain dual-band mixer with IF active balun and the linearity compensation dual-band mixer with active balun. The second parts are two novel circuit designs based on communication system’s. It contains: The low power high linearity phase shifter mixer for LTE application and the low power high linearity bulk driven mixer for WiMAX application.

In the first circuit design, an active balun is using to the input stage for dual-band concurrent mixer core. Because of the participation of the input active balun, the total conversion gain in mixer will be raised and the noise problem in the mixer core also restrain by the active balun.
The second design is a high conversion gain dual-band concurrent mixer. In this design, an output differential to single-ended balun was added in the output stage. This output balun not only makes the measurement easier, but also let the mixer have a higher conversion gain response.
From the first two circuit designs, we can find the active balun although bring the advantage of higher conversion gain, but result in a lower linearity performance. Therefore, the third circuit was designed to make up the linearity blemish when the active balun initiated.
In the fourth circuit, a novel phase shifter mixer design is proposed. This design reforms the defect of the mixer configuration in the reference paper, and shows a better measurement result to ensure our design indeed improving the circuit’s drawback.
The last but not the least, a bulk driven mixer with active balun is proposed. The bulk driven design makes a high linearity performance because of the less of the transconductance stage. The participation of active balun solves the problem of deficient in transconductance stage and provides a 5dB conversion gain.

These circuits are implemented by TSMC 0.18μm CMOS process. These chips have also been fabricated by the support of CIC in Taiwan.

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