- 學位論文
數位電視射頻(RF)信號增益補償電路
RF Signal Gain-Compensation Circuits for Digital TV Applications
摘要
本論文提出一應用於數位電視接收器前端低雜訊放大器增益射頻(Radio Frequency ;RF)信號增益補償技術。此補償技術是採用自行判定來決定是否需要補償，而不需要和外部一起做判定的方式，在電路架構上有一進兩出分享器、功率響應檢波器、寬頻放大器、遲滯比較器、二進一出寬頻切換開關、低壓差電壓調節等IC組合而成，以可達到自行判定並自行決定是否需要補償之目的。 本文所設計數位電視射頻(RF)信號增益補償電路是運用ADI(Analog Devices)公司的IC及一些基本電路來完成。其中的一進兩出分享器是可同時輸出兩組穩定信號。功率響應檢波器是輸出線性的直流控制電壓。固定寬頻放大器是將信號做固定的放大輸出。遲滯比較器用來確保輸出切換時不會發生震盪的現象。二進一出寬頻切換開關，具有很好的隔離特性，使輸入信號不會互相干擾。低壓差電壓調節器是提供一穩定輸出直流電壓(Direct Current ; DC)，讓系統能夠穩定的運作。此系統是可以獨立運作，不會因外在產品的不同，而產生搭配及相容性問題。並可把整體信號保持在一定範圍內輸出，不會因距離發射基地台的遠近，而隨著發射信號的強弱而改變輸出功率的大小，影響接收端所呈現的品質，並實現不需要和其他產品溝通才可作增益補償的目標。 本論文以實際應用層面，針對物體在移動時對信號的接收靈敏度(Sensitivity)作補償之設計，做廣泛的蒐集、探討與研究，並研究出一組可自行獨立運作不需配合其他系統，既可獨立生產之產品，並適用於數位電視射頻(Digital TV Radio Frequency)信號頻率範圍(470MHz~806MHz)[3]及類比電視射頻(Analog TV Radio Frequency)信號頻率範圍(54MHz~865MHz)[4]，不僅兼顧節省成本及降低功率耗損，還能達到符合電視系統所規定的頻率範圍，有效的廣泛使用不受區域系統的限制。
並列摘要
The thesis is to bring in an applicable method or technology aim to enhance the strength of Radio Frequency signal that is used in the low noise amplifier on the front end of digital television receiver. This technology has been designed in such a way that it will self-detect, without interfered by or relies on other variables outside the internal system, if the signal needs to be enhanced. Under the circuit structure, it is made out of the IC of Mean-Responding Power Detector, Broadband Fixed-gain Amplifier, Slow-Moving Comparator, splitter, Gain Amp, and Mux/SPDT to achieve the aim of making self-detection on signal enhancement. The digital TV RF signal enhancing circuit designed and mentioned herein the article uses IC and fundamental circuits by ADI (Analog Devices). Splitter is used to output two sets of stable signals. Responding power detector provides linear direct current. Gain amplifier amplifies signal in a fix ratio. Slow-moving comparator is used to avoid oscillation at the point of switching. Mux/SPDT recognized as having great isolation characteristics are utilized to prevent the input signals from interfering with each other. Low Dropout Voltage Regulator provides stable direct current ensuring a smooth and stable operation of the system. The system is meant to operate independently by itself and it will not encounter any compatibility issue when co-existing with other devices. Furthermore, the output signal is always maintained and kept within a certain range for the benefits that the scale of its output power will not change with the distance of where the base station is located. This unique characteristics assure the reception quality of the signal and further carry out the upside of its self-enhancing purpose alone. The thesis focuses on the actual application of how to enhance the sensitivity of the signal reception under moving status. With the extensive research, discussion, studies, and analysis, the result comes back positive where we are able to come out with a device that is able to self-operate without replying on other systems. It can be used in Digital TV Radio frequency within signal range 470MHz~806MHz(3), and Analog TV Radio Frequency within signal range 54MHz~865MHz(4).It not only meets all the frequency ranges specified by the TV system, but also lowers the cost and the power consumption. It can widely be used without encountering regional system restrictions.