1235554 九、發明說明： 【發明所屬之技術領域】 本發明係有關於電子電路，尤其是有關於鎖相回路（Phase1235554 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to electronic circuits, and particularly to phase-locked loops (Phase
Lock Loop ， pll)〇 【先前技術】 汛號處理技術在現今已能處理Giga赫茲的頻率，而鎖相 回路疋各種廣泛應用的基礎。簡單的說，鎖相回路是一種電 路，用以輸入的週期性訊號並輸出週期性的訊號，而輸入與輸 出之間具有某種恒定的相位關係。 第1圖係一習知的充電泵式（Charge_Pump Based)鎖相 回路100。相位頻率谓測器（PFD) 102比較參考訊號FRef的參 考相位eRef與回饋訊號Fbaek的回饋相位0baek，並產生一誤差訊 號。其中當參考相位θ…領切饋相位㊀⑽時，該誤差訊號是 一上升訊號（up Signal)’相對地，當參考相位㊀…落後回饋 相位㊀㈤時該誤差訊號是一下降訊號（d〇wnsignai)。而該誤 差訊號的脈衝寬度則表示了參考相位㊀…和回饋相位㊀㈤之 間的差值大小。 根據相位頻㈣測器102產生的誤差訊號（不論上升或下 降)’充電泵104 |生相當量的電荷。隨著該誤差訊號上升或 下降，則濾、波器1G6中的電荷也相對地增加或減少。在此的滤 阻R與一相當大的電 如此一來，該濾波器 波器10 6具有相當簡單的設計，包含_電 容α串聯，該串聯再與一電容Cs並聯。 1235554 106可看成是一積分器，用以累加從充電泵1〇4傳來的電荷， 而整個架構則稱為充電泵式（Charge-pump Based)濾波器。 當然其他各種型式的濾波器也可應用在本發明，而目的是在端 點Vlf產生一濾過電壓（f丨1 tered ν〇ι仏狀），使電壓電流轉換 器（V2C) 108對應產生一電流Ilf，傳送至電流控制振盪器 (current control oscillator，cc〇) 11〇。電流控制振盪器 110係用以產生週期性訊號（第丨圖的振盪訊號F_)，其頻率 係與该電流控制振盪器11〇的輸入電流呈某種函數關係（第一 圖Iu〇。除了做為鎖相回路1〇〇的輸出訊號之外，該電流控制 振盪器輸出的振盈訊號F_還可用於產生—回饋訊號^…，回 饋至該相位頻率偵測器102。 如果振盪訊號的頻率是該參考訊號FRef的頻率的倍數 或刀數，可在回饋路徑上選擇性地放置一個回饋除法器1C。 若不然，該回饋除法器112可將施於該回饋訊號Fbaw的係數設 為1。藉著在鎖相回路⑽中的回饋路徑反覆循環的效果，呈 穩定態的輸出訊號‘將具有相對該參考訊號FRef的固定相位 關係。除非刻意施加某些相位偏移’該輸人訊號和輸出訊號的 相位差將維持在最小偏移。 第圖顯示一第1圖中的電路所具有的操作曲線，其中 施：於端點Vlf的電壓透過電壓電流轉換器1〇8和電流控制振 盪為110導出一對應的輸出振盪訊號，頻率為F_。對低雜訊 1235554 鎖相回路應用而言，第1圖中的電流控制振盪器108具備低增 现（low gain)是很重要的事情。這表示該操作曲線的斜率廡 °亥要报低，如第4b圖中的操作曲線一般。也因此設計一個可 選擇操作曲線的電流控制振盪器以產生穩定的振盪回路訊號 是有必要的。 傳統上每一電流控制振盪器係在出廠時測試並定義其操 作曲線，以測定哪一個數位控制輸入值（例如第4b圖中的.2) 最適用於產生所需要的輸出頻率。當該電流控制振盪器已決定 用於特定應用場合時，固定的數位控制輸入值就永久性的燒錄 在哀置中。此電流控制振盪器的出廠測試和固接線路增加了製 造鎖相回路的成本，而且也永久限制了該鎖相回路的操作頻率 在一特定的操作曲線上。 【發明内容】 有鑑於此，本發明之目的在於提供一具有多重操作曲線的 鎖相回路。該鎖相回路包含一相位頻率偵測器，一充電泵式濾 波器 有限狀悲機器（f ini te state machine )，以及一具 有複數操作曲線的電壓控制振盪器（vc〇)。該相位頻率偵測器 根據一輸入訊號和一回饋訊號的比較結果，產生一誤差訊號。 该充電泵式濾波器產生一對應該誤差訊號的濾過電壓。而該有 限狀恶機器根據該輸入訊號和該回饋訊號的比對結果決定一 狀態值。 1235554 該電麼控制振盪器包含—電流單元，—電㈣流轉換器 (V2C)’以及-電流控制振盪器（⑽）。其中—操作曲線係根 據該狀態值而選定，而該電流單元對應地產生一第一電流。該 電壓電流轉換器在該操作曲線上選擇_操作點並將渡過電壓 轉換為-第二電流。該電流控制振蘯器根據該操作點產生一振 蘆όίΐ號’ 5亥振盪訊號同時用來產生一回饋訊號。 本‘明另一目的係提供一在鎖相回路中實作多重操作曲 線的方法。該方法包含下列步驟。 在一初始模式下，首先根據一輸入訊號和一回饋訊號的一 比較結果決定-操作曲線。接著提供—預設電流以在該操作曲 線上選擇-預設操作點’最後根據該預設操作點輸出—振盈訊 號。其中當該比較結果符合—既定條件，則切換至—執行模式。 在執行模式下，首先根據該輸入訊號與該回饋訊號的比較 結果，產生-濾、過電流。接著根據該攄過電流在該操作曲線上 選擇-操作點’最後根據該操作點輸出該振盪訊號。其中該振 盘訊號係用以產生該回饋訊號。 【實施方式】 本發明詳細實施例說明如下。 第2圖顯示本發明—實施例中的充電果式鎖相回路⑽。 ^貞相回路2〇"，相位頻率该測器1〇2,充電栗104,攄波 益1〇6 ’電壓電流轉換器1Q8，電流控制振與回饋除 1235554 的是為了讓鎖相回路2〇〇在一 操作曲線。 法器112皆與第1圖中的鎖相回路⑽中所包含的元件相同。 此外，該鎖相回路⑽還包含了頻率偵測器2〇2，有限狀態機 器204,電流單元206和電流加法器2〇8。這些元件的設計目 啟動時就能夠自動選擇一適當的 在第2圖中’該頻率細2G2_參考卿糾和回饋訊孤^之間 的頻率差異，而該有限狀態機器2G4則用以判斷其狀態是否符合一條件。 該有限狀態機11204發綠位控制輸人值N(其值依實際電路而不同）至電 流單元206以對應地選擇-適當的操作曲線，藉以輸出一電流。 該鎖相回路測運作於兩種模式下，初始模式與執行模主要精神 所在是’ t«限狀腿施加—數位參數至該電流單元識，以決定要 採用哪-操作鱗，織該電壓電流轉換器⑽藉轉換施加於端點^上的 一輸入電壓至-電流LF來決定該操作曲線上的操作點。最後輸㈣總電流 (電流單元206的輸出電流加上lLF)便能夠使得電流控制振盈器ιι〇運作 於目標操作曲線上。 在初始模式下，該充電泵1G4是關閉的，而—預設電壓被施加於^上， 例如第3圖中所示的1/2—。該有限狀態機器2〇4產生一系列數位控制輸 入值N，傳送至電流單元206，依序選擇操作曲線。電壓電流轉換器簡將 端點vLF上的電壓轉換為一電流II”該電流Iu?與從電流單元流出的電流， 在電流加法器2〇8中相加並傳至電流控制振盪器11〇,以決定最適當的操作 曲線。對每—操作曲線而言，伴隨所施加的參考電壓VRef，電流控制振盪器 1235554 產生^有丨旦定頻率的振蘯訊號F〇SC：，且透過不斷回饋循環，該最適當 被確定並叙，接著便進人執行模式。 在執行模式中，電流單元2〇6運作於在該初始模式中選定的最適當操 =曲線’預叹電塵1/2_是關閉的，而充電泵綱則啟動開始微調該最適 田操作曲線上的操作點。在第2圖中，藉由在相位頻率細器⑽中比對 參考域^和_峨^，—上升纖或—下降織被施加於該充電果 104 ’因此可在端點Vu?上產生―慮過電壓。電壓電流轉換器⑽麟據過電 壓轉換為電流該電流Iu?和從電流單元2G6輸出的電流由該電流加法器 208相加並施加至該電流控制振堡器11〇以產生一振盪訊號&。在執行模 式中，在微調時，如果操作曲線並不適當，端點Vlf上的遽過電壓可能超過 0V至VDD的範圍。當發生此事時，便切回初始模式，重新選擇一條適當的 操作曲線。藉此重覆步驟，振盪訊號的頻率最終會收斂於目標值上，如第 4b圖所示。 第3圖顯示该充電泵式遽波器的詳細方塊圖。在初始模式下，電流源 被一開關C1所關閉。沒有電流會從該充電泵104輸出，而端點Vlf的電壓值 則預設在1/2VDD。在另一實施例中，端點Vlf的電壓值可以是其他經過計算 過後選擇的值，視第2圖中有限狀態機器204的設計而定。在執行模式下， 該開關C1被開啟以啟動電流源，同時該預設電壓值1/2VDD則被關閉。該 充電录104開啟’並根據相位頻率偵測器102產生的上升訊號或下降訊號， 對應地從端點Vlf輸出濾過電壓。 第4b圖顯示鎖相回路200中複數操作曲線。在一實施例中，一適當操 1235554 作曲線（N=2)首次在初始模式中透過有限狀態機器204和電流單元206而 被選定。接著切換到執行模式，並透過回儀，端點Vlf上的電壓值（預設是 1/2VDD)被微調偏移，使操作點位在所要的振盪頻率F〇sc。 上述實施例說明本發明的鎖相回路提供的優點克服了習 知鎖相回路的缺點。因操作曲線在啟動時可自動鎖定在適當的 操作曲線上，不需要在出廠時預先焊死該電流單元。此外不需 要為不同的應用準備各種不同的電流單元，因為該電流單元適 用範圍已經具備彈性擴張的能力，視需要可自動切換至適當的 操作曲線。同時也因為電流單元的設定被沒有被焊死，該鎖相 回路在面臨各種不同應用時可重複再利用。每當該鎖相回路開 啟，該電流單元將自動跳到適當操作曲線，且此步驟在有必要 時可重複進行，例如重置時。 本發明的另一優點是，只需使用很少量的額外元件便能改 良習知的鎖相回路100。雖然計時器和有限狀態機器可能不存 在於習知鎖相回路中，但因為都是低速邏輯電路，其成本相對 於所能節省的大量成本，是可忽略的。 本發明雖以較佳實施例揭露如上，然其並非用以限定本發 明的範圍，任何熟習此項技藝者，在不脫離本發明之精神和範 圍内，當可做各種的更動與潤飾，因此本發明之保護範圍當視 後附之申請專利範圍所界定者為準。 【圖式簡單說明】 11 1235554 第1圖係為習知鎖相回路的方塊圖； 第2圖係為本發明的鎖相回路方塊圖； 第3圖係為第2圖中的充電泵式濾波器更詳細電路圖； 第4a圖係為習知的操作曲線；以及 第4b圖係為本發明的多重操作曲線。 【主要元件符號說明】 102〜 相位頻率偵測器 104〜 充電泵 106〜 濾波器 108〜 電壓電流轉換器 110〜 電流控制振盪器 112〜 回饋除法器 202〜頻率偵測器 204〜 有限狀態機器 206〜 電流單元 208〜 電流加法器 12Lock Loop, pll) 〇 [Previous technology] The flood number processing technology can now handle the frequency of Giga Hertz, and the phase-locked loop is the basis for a wide variety of applications. Simply put, a phase-locked loop is a circuit that is used to input periodic signals and output periodic signals, and there is a constant phase relationship between the input and output. Fig. 1 is a conventional charge pump type (Charge_Pump Based) phase-locked loop 100. The phase frequency counter (PFD) 102 compares the reference phase eRef of the reference signal FRef with the feedback phase 0baek of the feedback signal Fbaek, and generates an error signal. Wherein, when the reference phase θ ... the leading-cut feed phase ㊀⑽, the error signal is an up signal (relatively, when the reference phase ㊀ ... is behind the feedback phase ㊀㈤, the error signal is a down signal (d0wnsignai) . The pulse width of the error signal indicates the difference between the reference phase ㊀ ... and the feedback phase ㊀㈤. Based on the error signal (whether rising or falling) generated by the phase frequency detector 102, the charge pump 104 generates a considerable amount of charge. As the error signal rises or falls, the charge in the filter and wave filter 1G6 also relatively increases or decreases. The filter R here has a relatively large capacitance. As a result, the filter wave 106 has a relatively simple design, which includes a capacitor _ in series, which is then connected in parallel with a capacitor Cs. 1235554 106 can be regarded as an integrator to accumulate the charge transmitted from the charge pump 104, and the entire structure is called a charge-pump based filter. Of course, various other types of filters can also be applied in the present invention, and the purpose is to generate a filtered voltage (f 丨 1 tered νι 仏) at the terminal Vlf, so that the voltage-to-current converter (V2C) 108 generates a current correspondingly. Ilf, transmitted to a current control oscillator (cc) 11o. The current-controlled oscillator 110 is used to generate a periodic signal (oscillation signal F_ in FIG. 丨), and its frequency is in a certain functional relationship with the input current of the current-controlled oscillator 110 (first figure Iu〇. In addition to doing In addition to the output signal of the phase-locked loop 100, the vibration signal F_ output by the current-controlled oscillator can also be used to generate a-feedback signal ^ ..., which is fed back to the phase frequency detector 102. If the frequency of the oscillation signal It is a multiple or frequency of the reference signal FRef, and a feedback divider 1C can be selectively placed on the feedback path. If not, the feedback divider 112 can set the coefficient applied to the feedback signal Fbaw to 1. By the effect of the feedback path in the phase-locked loop 反, the output signal in a stable state will have a fixed phase relationship with respect to the reference signal FRef. Unless some phase offset is intentionally applied, the input signal and output The phase difference of the signal will be maintained at a minimum offset. The figure shows an operating curve of the circuit in figure 1, where the voltage at the terminal Vlf passes through the voltage-current converter 108 and The current-controlled oscillation is 110 to derive a corresponding output oscillation signal with a frequency of F_. For low-noise 1235554 phase-locked loop applications, it is important that the current-controlled oscillator 108 in Figure 1 has a low gain. This means that the slope of the operating curve 报 ° should be reported as low as in the operating curve in Figure 4b. Therefore, it is necessary to design a current-controlled oscillator with an optional operating curve to generate a stable oscillation circuit signal. Traditionally, each current controlled oscillator is tested at the factory and its operating curve is defined to determine which digital control input value (such as .2 in Figure 4b) is most suitable for generating the required output frequency. When When the current-controlled oscillator has been determined to be used in a specific application, the fixed digital control input value is permanently burned in the mourning. The factory test and fixed wiring of this current-controlled oscillator adds to the phase-locked loop manufacturing. Cost, and also permanently limits the operating frequency of the phase-locked loop on a specific operating curve. SUMMARY OF THE INVENTION In view of this, the object of the present invention is to A phase-locked loop with multiple operating curves is provided. The phase-locked loop includes a phase frequency detector, a charge pump filter finite state machine, and a voltage control with a complex operating curve. Oscillator (vc0). The phase frequency detector generates an error signal according to the comparison result of an input signal and a feedback signal. The charge pump filter generates a pair of filtering voltages corresponding to the error signal. The finite state The evil machine determines a state value according to the comparison result of the input signal and the feedback signal. 1235554 The electric control oscillator includes a current unit, an electric current converter (V2C) 'and a current control oscillator (⑽). Among them, the operation curve is selected according to the state value, and the current unit correspondingly generates a first current. The voltage-to-current converter selects the _ operating point on the operating curve and converts the crossing voltage to a -second current. The current-controlled vibrator generates a vibration signal according to the operating point, and a oscillating signal is used to generate a feedback signal. Another object of the present invention is to provide a method for implementing multiple operation curves in a phase locked loop. The method includes the following steps. In an initial mode, the operation curve is first determined based on a comparison result of an input signal and a feedback signal. Next, a preset current is provided to select on the operating curve-a preset operating point 'and finally a vibrating signal is output according to the preset operating point. Wherein, when the comparison result meets the -predetermined conditions, it switches to the execution mode. In the execution mode, first, according to the comparison result between the input signal and the feedback signal, a filter-overcurrent is generated. Then select-operating point 'on the operating curve according to the 摅 overcurrent, and finally output the oscillating signal according to the operating point. The vibration signal is used to generate the feedback signal. [Embodiment] The detailed embodiment of the present invention is explained as follows. FIG. 2 shows a charging fruit-type phase-locked loop ⑽ in an embodiment of the present invention. ^ The phase phase loop 2〇 ", the phase frequency of the tester 102, the charging pump 104, the 摅 波 益 1066 'voltage current converter 1Q8, the current control vibration and feedback division 1235554 is to make the phase locked loop 2 〇〇 In an operating curve. The implements 112 are the same as those included in the phase-locked loop ⑽ in FIG. 1. In addition, the phase-locked loop ⑽ also includes a frequency detector 202, a finite state machine 204, a current unit 206, and a current adder 208. When the design of these components is started, an appropriate frequency difference between 'the frequency is fine 2G2_reference frequency correction and feedback solitary ^ in Figure 2 is automatically selected, and the finite state machine 2G4 is used to judge its Whether the status meets a condition. The finite state machine 11204 sends a green level control to input a value N (the value of which varies depending on the actual circuit) to the current unit 206 to select a corresponding-appropriate operating curve accordingly to output a current. The phase-locked loop test operates in two modes. The main spirit of the initial mode and the execution mode is' t «limit leg application-digital parameters to the current unit identification to determine which to use-operating scale, weaving the voltage and current The converter determines an operating point on the operating curve by converting an input voltage applied to the terminal ^ to a current LF. Finally, the total input current (the output current of the current unit 206 plus lLF) can make the current control oscillator operate on the target operating curve. In the initial mode, the charge pump 1G4 is turned off, and-a preset voltage is applied to ^, such as 1/2 shown in Fig. 3-. The finite state machine 204 generates a series of digital control input values N, transmits them to the current unit 206, and sequentially selects operating curves. The voltage-to-current converter simply converts the voltage at the terminal vLF into a current II. The current Iu? And the current flowing from the current unit are added in a current adder 208 and passed to the current-controlled oscillator 1110. To determine the most appropriate operating curve. For each operating curve, with the applied reference voltage VRef, the current-controlled oscillator 1235554 generates an oscillation signal F0SC with a fixed frequency: and through continuous feedback cycles The most appropriate is determined and described, and then enters the execution mode. In the execution mode, the current unit 206 operates at the most appropriate operation selected in the initial mode = curve 'predict electric dust 1 / 2_ yes Closed, and the charge pump platform starts to fine-tune the operating point on the optimal field operation curve. In Figure 2, by comparing the reference domain ^ and _ 埃 ^ in the phase frequency thinner 上升, the rising fiber or —Down weave is applied to the charging fruit 104 ′, so an overvoltage can be generated at the terminal Vu ?. The voltage-current converter ⑽Lin converts the current Iu? According to the overvoltage and the current output from the current unit 2G6 is The current adder 208 adds and Added to this current controls the vibrator 11 to generate an oscillating signal &. In the execution mode, during trimming, if the operating curve is not appropriate, the over-voltage on the terminal Vlf may exceed the range of 0V to VDD. When this happens, switch back to the initial mode and re-select an appropriate operating curve. By repeating this step, the frequency of the oscillating signal will eventually converge to the target value, as shown in Figure 4b. Figure 3 shows the Detailed block diagram of the charge pump type wave filter. In the initial mode, the current source is turned off by a switch C1. No current will be output from the charge pump 104, and the voltage value of the terminal Vlf is preset at 1 / 2VDD. In another embodiment, the voltage value of the terminal Vlf may be another value selected after calculation, depending on the design of the finite state machine 204 in Fig. 2. In the execution mode, the switch C1 is turned on to start the current. Source, at the same time the preset voltage value of 1 / 2VDD is turned off. The charging record 104 is turned on and the filtered voltage is output from the terminal Vlf correspondingly according to the rising signal or falling signal generated by the phase frequency detector 102. Figure 4b Show lock The complex operation curve in the loop 200. In one embodiment, an appropriate operation 1235554 curve (N = 2) is selected for the first time in the initial mode through the finite state machine 204 and the current unit 206. Then it switches to the execution mode and passes through Returning to the instrument, the voltage value on the endpoint Vlf (the default is 1 / 2VDD) is fine-tuned and shifted, so that the operating point is at the desired oscillation frequency Fsc. The above embodiment illustrates that the advantages provided by the phase-locked loop of the present invention overcome The disadvantages of the conventional phase-locked loop are known. Because the operating curve can be automatically locked to the appropriate operating curve at startup, there is no need to pre-solder the current unit at the factory. In addition, it is not necessary to prepare various current units for different applications because The scope of application of the current unit already has the ability to expand elastically, and it can automatically switch to the appropriate operating curve as needed. At the same time, because the setting of the current unit is not welded to death, the phase-locked loop can be reused when facing various applications. Whenever the phase-locked loop is turned on, the current unit will automatically jump to the appropriate operating curve, and this step can be repeated if necessary, such as during reset. Another advantage of the present invention is that the conventional phase-locked loop 100 can be improved using only a small number of additional components. Although timers and finite state machines may not exist in conventional phase-locked loops, because they are low-speed logic circuits, their costs are negligible relative to the large cost savings. Although the present invention is disclosed as above with a preferred embodiment, it is not intended to limit the scope of the present invention. Any person skilled in the art can make various modifications and retouches without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application. [Schematic description] 11 1235554 Figure 1 is a block diagram of a conventional phase-locked loop; Figure 2 is a block diagram of a phase-locked loop of the present invention; Figure 3 is a charge pump filter of Figure 2; Detailed circuit diagram; FIG. 4a is a conventional operation curve; and FIG. 4b is a multiple operation curve of the present invention. [Description of main component symbols] 102 ~ Phase frequency detector 104 ~ Charge pump 106 ~ Filter 108 ~ Voltage current converter 110 ~ Current controlled oscillator 112 ~ Feedback divider 202 ~ Frequency detector 204 ~ Finite state machine 206 ~ Current unit 208 ~ Current adder 12