應用於毫米波相位陣列之電路設計

Design of Millimeter-wave Phased Array Circuits

周庭義(Ting-Yi Chou)

指導教授 ： 郭建男

國立交通大學/電機學院/電子工程系所/碩士(2020年)

摘要

隨著第五代行動通訊的演進，資料傳輸量及傳輸速度勢必需要提升，而毫米波頻段能提供相當大的傳輸頻寬，因此毫米波頻段相關之電路設計需求也日益劇增，相位陣列之波束成形技術為毫米波重要技術之一，相移器(Phase Shifter)及可控制增益放大器(Variable Gain Amplifier, VGA)為波束成形技術(Beamforming)中相當重要之電路。本論文針對相移器及可控制增益放大器去做設計。
為了較容易控制相位陣列，因此選擇採用被動切換式相移器去控制每一路訊號的相位，但因為被動切換式相移器在毫米波頻段的饋入損耗(Insertion Loss)相當嚴重、控制相位時的損耗變異也會不便於應用以及相較於主動式相移器來說設計上使用較多電感造成面積消耗較大，因此被動切換式相移器設計上著重於減少饋入損耗、損耗變異及縮小面積這三個方向。然而，相移器造成的損耗變異不是一個輕易能去克服的問題，另一個解決的辦法是使用可控制增益放大器去補償相移器造成的損耗變異，亦或是去調整不同所需的輸出功率位準，隨著可控制增益放大器的操作頻率越高，控制增益的同時相位變異也會增加，因此可控制增益放大器設計重點在於控制增益時相位能維持在定值以利於相位陣列應用。
本論文提出利用TSMC 90 nm製程實現5-bits切換式相移器，利用傳輸線模型搭配切換開關實現微小化設計，並將電晶體基極浮接用以減少基極損耗，加上透過電感佈局設計去縮小相移器佈局面積。本次設計相移器因為設計在接收端內，故量測無法單獨得知相移器損耗大小，電路主要操作在24 GHz。量測單路增益為7.55 dB，反射損耗大於10dB，雜訊指標為11.8 dB，其方均根相位誤差(rms phase error) 為7.4°，損耗變異為4.8 dB。可控制增益放大器操作在1.2 V電壓供應，28 GHz。其利用設計不同回授網路去降低相位變異，量測結果可控制增益範圍可達38.1 dB，相位變異小於7度，最大增益17.7 dB ，消耗功率為8.3 mW，使得增益控制與相位之間可以達到一定程度的互不影響。

關鍵字

毫米波 ； 相位陣列 ； 相移器 ； 可調整增益放大器

並列摘要

With the evolution of the fifth generation mobile communication, the speed and amount of data transmission must be increased. Millimeter-wave( mmWave ) can provide a considerable transmission bandwidth. Therefore, the chip requirements in mmWave are also increasing rapidly. Beamforming technology is one of the important technologies of mmWave. Phase shifter and variable gain amplifier (VGA) play an important role in the beamforming technology. This thesis focuses on phase shifter and VGA.
In order to control phased-array easily, switch-type-phase-shifter (STPS) is a good choice. Due to the serious insertion loss of STPS in mmWave, the loss variation that causes problems in phased-array system, and many inductors used in STPS’s design consumes more layout area than active phase shifter. Thus, reducing insertion loss, loss variation, and minimizing the layout area are the issues must be solved. However, loss variation is hardly to be improved. VGA is another solution. It can compensate the loss variation caused by phase shifter, and also adjust different output power level. The higher operating frequency is, the heavier phase variation of VGA is. The design point of VGA must focus on “Get constant phase when larger gain control range”
In this thesis, the proposed 5-bits STPS mainly use the simple model of transmission line and the switch to fulfill the miniaturized design. Use body-floating technique of transistor to reduce body loss and arrange the inductor layout to minimize the overall layout. Because the STPS is included in receiver, the loss of STPS can’t be separated. This chip operates at 24 GHz, the gain of single path is 7.55 dB, return loss is more than 10 dB, NF is 11.8 dB, rms phase error is 7.4° and loss variation is 4.8 dB. The proposed VGA operates with 1.2 V supply at 28 GHz. Design a new feedback network to achieve low phase variation. The measurement results show that gain control range is 38.1 dB and phase variation is less than 7°, maximum gain is 17.7 dB and power consumption is 8.3 mW. To some degree, the gain control is independent of phase.

並列關鍵字

Phased Array ； Phase Shifter ； Variable Gain Amplifier ； VGAs

參考文獻

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