數碼電路

上圖係一個 Arduino 數碼電路；下圖係 4 吓數碼訊號嘅抽象圖解－每吓數碼訊號一係高電壓（1）一係低電壓（0），數碼電路會用數碼訊號嚟傳達資訊。

數碼電路（粵拼：sou3 maa5 din6 lou6，英文：Digital circuit），又或者叫數碼集成電路，係指用數碼方式嚟傳達訊號嘅電子電路；相對於用模擬方式傳訊嘅模擬電路^[1]^[2]。研究「點樣設計數碼電路」嘅電子學子領域，就係所謂嘅數碼電子學（Digital electronics）。

數碼電路係廿一世紀初電腦同電訊嘅重要根基：喺概念上，一吓數碼訊號由一個離散（discrete）物理量集建構成，表示一連串離散嘅數值－吓數碼訊號嘅一個可能數值（例如 0）同下一個可能數值（例如 1）之間實會有個最細嘅可能差距，冇話斬件到幾細都得，例如數值冇得係 0.5；呢種訊號喺廿一世紀初嘅數碼電腦同各種電子架生當中好常用－呢啲機械會傳一串串由有電（1）同冇電（0）組成嘅訊號，並且用呢一串串嘅數值表示一啲資訊，用唔同嘅 1-0 組合代表唔同嘅符號，例如 0000 表示英文字母 A，0001 表示字母 B... 呀噉，達致「用連串電流傳達信息」噉嘅效果^[3]^[4]。

喺實際應用上，數碼電路可以搵邏輯門（logic gate）等嘅電子元件砌出嚟。响廿一世紀初，數碼電路可以話無處不在咁滯，電腦、智能電話^[5]以至遊戲機^[6]等嘅科技產品都會用到數碼電路，而數碼電子學亦自然成為咗電子工程等領域上嘅必備知識之一。

基礎

數碼訊號（digital signal）係訊號嘅一種。一個數碼訊號由一個離散（discrete）嘅物理量集建構成，表示一連串離散嘅數值－一個數碼訊號嘅一個可能數值（例如 0）同下一個可能數值（例如 1）之間實會有個最細嘅可能差距，冇話斬件到幾細都得（例如數值冇得係 0.5）^[7]^[8]。數碼訊號喺廿一世紀嘅數碼電腦同各種電子架生當中好常用：呢啲機械會傳一串串由有電（1）同冇電（0）組成嘅訊號（好似下圖噉），並且用呢一串串嘅數值表示一啲資訊，簡單講就係唔同嘅 1-0 組成代表唔同嘅符號，當中「符號」包括咗羅馬字母同數字呀噉（詳情可以睇吓 ASCII 同 Unicode）；另一方面，亦都有啲數碼訊號做法係有三個或者以上嘅可能數值嘅^[9]^[10]。

數碼訊號之所咁常見，係因為呢種訊號有好多好處。數碼訊號其中一個最大嘅好處就係相對冇咁易受雜音影響－喺現實世界，一個訊號喺傳送嘅中途梗會或多或少噉受到干擾，跟住會走少少樣：

如果個訊號係模擬訊號（睇下面），個訊號嘅準確性實會（機率 = 100%）受影響；
相比之下，如果嗰個訊號係數碼訊號嘅話，個系統嘅設計者可以（例如）事先設定好部收訊號用嘅機械，叫部機跟「如果電壓值細過 $V_{t}$ ，就當個訊號係 0」同「如果電壓值大過 $V_{t}$ ，就當個訊號係 1」噉嘅規律行事；假想傳訊號嗰一刻，個訊號嘅可能數值分別係 $V_{0}$ 同 $V_{1}$ ；理論上，如果 $|V_{t}-V_{0}|$ 同 $|V_{t}-V_{1}|$ 呢個數值夠大，就算接收到嗰個訊號受干擾走咗樣，最後得到嘅資訊都唔受影響^[11]^[12]。

好似係下圖噉，下圖 Y 軸表示收到嗰吓訊號嘅電壓值。喺現實世界，訊號實會受到干擾，所以實際收到個訊號近乎冇可能會完全等如一個特定數值。

數碼訊號可以由模擬訊號轉化而成：舉個例，家陣有部機，佢喺每個時間點會收一個數值係連續（可以係小數點後 n 個位）嘅電壓作為輸入，而輸出就係一串二元（binary）嘅數碼訊號（數值一係 1 一係 0），每 16 個訊號係一個二進制數字，代表一個時間點嘅輸入電壓值，例如如果輸出係 0000 0001 0010 0010，就代表輸入電壓值係 290 V－290 喺二進制入面係「1 0010 0010」。事實上，呢種做法喺現代電子工程當中極之常見，例如遊戲機嘅遊戲搖桿都用咗呢種做法，數碼電路就係呢啲噉嘅架生入面、傳數碼訊號嘅電子電路^[13]。

理論概念

建構部件

設計

睇埋

電腦架構

攷

↑ Jain, R. P. (2003). Modern digital electronics. Tata McGraw-Hill Education.
↑ Maini, A. K. (2007). Digital electronics: principles, devices and applications. John Wiley & Sons.
↑ Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."
↑ Analogue and Digital Communication Techniques. Archived from the original on 2017-12-17. "A digital signal is a complex waveform and can be defined as a discrete waveform having a finite set of levels."
↑ Lee, J. I., Chang, I., Pradhan, A. S., Kim, J. L., Kim, B. H., & Chung, K. S. (2015). On the use of new generation mobile phone (smart phone) for retrospective accident dosimetry. Radiation Physics and Chemistry, 116, 151-154.
↑ It's a-Me, Mario! Here to Teach You The Difference Between Analog and Digital 互聯網檔案館嘅歸檔，歸檔日期2022年1月17號，.. Autodesk.
↑ Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."
↑ Analogue and Digital Communication Techniques. Archived from the original on 2017-12-17. "A digital signal is a complex waveform and can be defined as a discrete waveform having a finite set of levels."
↑ Paul Horowitz; Winfield Hill (2015). The Art of Electronics. Cambridge University Press.
↑ Proakis, John G.; Manolakis, Dimitris G. (2007-01-01). Digital Signal Processing. Pearson Prentice Hall.
↑ Horowitz, Paul; Hill, Winfield (1989). The Art Of Electronics, 2nd Ed. Cambridge University Press. pp. 471-473.
↑ Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."
↑ Hoeschele, D. F. (1994). Analog-to-digital and digital-to-analog conversion techniques (Vol. 968). New York: Wiley.

[1] Jain, R. P. (2003). Modern digital electronics. Tata McGraw-Hill Education.

[2] Maini, A. K. (2007). Digital electronics: principles, devices and applications. John Wiley & Sons.

[3] Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."

[4] Analogue and Digital Communication Techniques. Archived from the original on 2017-12-17. "A digital signal is a complex waveform and can be defined as a discrete waveform having a finite set of levels."

[5] Lee, J. I., Chang, I., Pradhan, A. S., Kim, J. L., Kim, B. H., & Chung, K. S. (2015). On the use of new generation mobile phone (smart phone) for retrospective accident dosimetry. Radiation Physics and Chemistry, 116, 151-154.

[6] It's a-Me, Mario! Here to Teach You The Difference Between Analog and Digital 互聯網檔案館嘅歸檔，歸檔日期2022年1月17號，.. Autodesk.

[7] Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."

[8] Analogue and Digital Communication Techniques. Archived from the original on 2017-12-17. "A digital signal is a complex waveform and can be defined as a discrete waveform having a finite set of levels."

[paulhill2015-9] Paul Horowitz; Winfield Hill (2015). The Art of Electronics. Cambridge University Press.

[10] Proakis, John G.; Manolakis, Dimitris G. (2007-01-01). Digital Signal Processing. Pearson Prentice Hall.

[horowitz1989-11] Horowitz, Paul; Hill, Winfield (1989). The Art Of Electronics, 2nd Ed. Cambridge University Press. pp. 471-473.

[dueck-12] Robert K. Dueck. Digital Design with CPLD Applications and VHDL. "A digital representation can have only specific discrete values."

[hoeschele1994-13] Hoeschele, D. F. (1994). Analog-to-digital and digital-to-analog conversion techniques (Vol. 968). New York: Wiley.

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