409452 A7 B7 經濟部中央標準局員工消費合作社印製 五、發明説明（1 ) 自主式頻率產生電路 1. 摘要 積體電路振盪器的頻率得以維持固定而不受溫度變化之影響，乃係藉著溫度補 償的設計而達成。一個具有對溫度敏感的元件之電壓控制的振盪器，必須具有 一個溫度相關的電壓控制元件以作爲溫度補償。當操作電流維持一定時，許多 種類的振盪器例如鬆弛振盪器以及環狀振盪器等的頻率可以保持一定。操作電 流通常是由電流源所產生，且是一個電壓對電流之轉換器，產生一個電流其大 小等於電壓對電阻的比率。因爲半導體電阻具有一個主的溫度係數，一個具有 正的溫度係數的控制電壓通常被使用於產生一個不隨溫度改變的電流源。正的 溫度係數可以取自於兩個正向偏壓的pn接合電壓之差別，數値的大小則取決於 Pn接面的大小，這個數値也可以進一步被放大或衰減。 2·背景說明 本發明係有關於頻率產生器，特別是指積體電路的時鐘產生器。多頻處理系統 在最近的VLSI系統應用中愈來愈流行，在這些應用當中，通常使用一個外部 的時鐘源，用以產生所需的信號頻率產生源。一個外部的時鐘源需要一個石英 振盪器，這會增加積體電路的包裝腳數，也會增加印刷電路板的佈局面積，以 提供該外部時鐘源所佔用之空間。從一個系統產品的角度觀之，一個外部時鐘 源由於雜散電容的增加，將會降低了時鐘信號的整體性以及高頻運作的特性。 同時•所增加的電路也會增加高頻電磁輻射以及信號間之交錯干擾。因此，外 部時鐘源的使用不但增加系統成本，同時也降低產品功能例如速度減慢以及電' 磁干擾增加...等。 過去幾年來’個人電腦的功能提昇許多，這是由於PC母板(mother board)提高 了處理速度以及準確度的緣故。傳統的母板所使用的時鐘計時源多是採用「相 位鎖定迴路」【phase-locked loop, PLL】、以及時鐘產生器積體電路。典型的是， 該時鐘源採用14.318 MHz石英振盪器作爲計時參考。因爲石英振盪器必須緊靠 著「相位鎖定迴路」晶片的關係，所以必須佔用印刷電路板上的一塊面積，而 且它也會輻射電磁波而增加信號處理的干擾以及交錯雜訊。 一般設計都是希望使用鬆弛振盪器或是環狀振盪器整合於系統產品的積體電路 中< 然而，此一設計很困難獲得一個對溫度變化不敏感的穩定頻率，這是因爲 溫度改變時，元件的値以及操作電流會改變。雖然，使用一個能帶間隙參考電 壓【energy band-gap voltage reference, Vref】以便獲得一個不受溫度變化影響的 定電壓是可能的，但是電路元件，特別是半導體電阻不可能做到不受溫度變化 影響的。 3.本發明的主要目的 本發明的目的之一是：不使用外部的石英，以便節省積體電路的面積’也節省 印刷電路板的面積。本發明的目的之二是：對於積體電路中的元件値的溫度變 化作補償。本發明的目的之三是：減低PC系統中的電磁干擾，並且增加母板 的整體性。本發明的目的之四是：提高PC系統的穩定度以及可靠度。 本紙張尺度通用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注意事項再ίΛ寫本頁) 經濟部中央標爭局8工福利委員會印製 409452 ____H3 i — '~ ~ 這些目的可以藉著一個存在於積體電路內部的自主式頻率產生電路而達成，一 個隨溫度之改變而改變輸出電壓的電壓供應器被用來作爲電壓控制的振盪器， 以便獲得一個穩定的頻率。電源供應器連接一個正溫度係數電壓與串聯一個倉 溫度係數電壓。負溫度係數電壓係來自於PN接面的正向偏壓，正溫度係數^ 壓則是係來自於操作於不同電流密度的兩個正向偏壓介面電壓差。當正^度係 數電壓超過負溫度係數電壓時，控制電壓具有正溫度係數，反之亦然。 ' —個可程式控制之電壓緩衝器(或是單一增益裏壓緩衝器)提供了參考電壓的一 個可調式控制，一個「電壓控制的振盪器」【voltage-controlledoscillator VCO】， 依據控制電壓的輸出，可以產生一個對映的頻率輸出。 ’ 本發明所使用的振盪器可以是鬆弛振盪器、環狀振盪器、或是其他適用於積體 電路中的振盪器。使用在一個具有相同的溫度係數的電壓控制電流源的電阻， 可以藉著彌補其正溫度係數，而使得操作電流可以保持一定。 4. 圖示說明 圖la.是本發明之自主式頻率產生電路的方塊圖，使用可程式控制之電壓緩衝器。 圖lb.是本發明使用固定增益電壓緩衝器的方塊圖。 圖2.是具有可變溫度係數的電源供應器。 圖3.是電壓對電流轉換器以作爲電流源。 圖4.是一個電壓控制的鬆驰振盪器。 圖5.是一個環狀振邊器。 圖6a.是電壓控制的環狀振盪器。 圖6b.是環狀振盪器的電流源。 5. 本發明的詳細說明 圖la.是本發明之自主式頻率產生電路的方塊圖，使用可程式控制之電壓緩衝 器；圖lb.是本發明使用固定增益電壓緩衝器的方塊圖。一個電壓控制振盪器 是藉著一個具有事先決定的溫度係數的參考電壓的控制，而獲得一個對於溫度 變化不敏感的頻率。 圖2.是具有可變溫度係數的電源供應器。兩個相同的MOSFET Q3以及Q4， /其源極連接到一個負的電源供應器Vss，其閘極連接到「運算放大器」 【叩erational amp丨ifier，0P】的輸出端。Q3的汲極，藉著電阻汜，連接到運算 放大器的反向輸入端A、以及一個「雙載子電晶體」【bipolar transistor, BJT】的 射極Qb Q4的汲極，藉著電阻R2，連接到運算放大器的非反向輸入端B，又 藉著電阻R1，連接到雙載子電晶體的射極Q2。Q1以及Q2的基極連接到共極， 集極則連接到正電源供應器VDD。 Q4充當反向器是以(R2+RHQ2的射極接面作爲負載’在非反向輸入端B會產 生一個負的回饋電壓，由於運算放大器的虛擬接地的特性，A，B兩點的電壓必 須相同，Q3以及Q4的汲極電流必須相同而且等於I。Q2的射極區Ae2是A 倍於Q1的射極區Ael。當Q1以及Q2的基底射極接面電壓降分別是Vbe〗以 本紙張尺度逋用中國國家標準(CNS)A4規格(210X297公釐) 經濟部中央標準局*5工福利委員會印製 409452 H3 —~ ^ 及Vbe2時，IR1的壓降會是Vbel-Vbe2，也就是： I=(Vbel-Vbe2)/Rl (1) 同時，輸出電壓Vref會是： Vref=-Vbel-(Vbel-Vbe2)R2/RI. (2) BJT的射極電流是： V Ie=Ae J〇[exp. (q Vbe/kT)-1 ] (3) 其中的Jo是飽和電流密度，且正比於Γ2 3qVg/kT. q是電荷=1.6*1〇_19庫倫 k是波茲曼常數=1.38*10_23J/°K T是絕對溫度。K。 在不同的溫度下，爲了維持Q1射極電流的恆定，將方程式(3)對溫度微分並且 設定爲零，可以得到溫度變化(ΔΤ)下所需要的變化(AVljel): △Vbel/Z\T=-2mV/°K (4) 當任意溫度T高於參考溫度T。時，相對的VbelCD會是： Vbel(T) = Vbel(T0)-0.002(T-T〇) (5) 因此，Vbe〗有一個負的溫度係數。 另外，由方程式(1)和(2)可以獲得如下的演算結果： IRI =(Vbe 1 - Vbe2) =(kT/q)[ln(I/Ae 1 )-ln(I/Ae2)] =(kT/q)lnA ⑹ 電流H(kT/q)lnA]Rl正比於T。 R2的壓降有正的溫度係數。 IR2=(R2/Rl)(kT/q)lnA (7) 參考電壓變成： Vref(T)=-[Vbel(To)-0.002(T-To)]-[(R2/Rl)(k/q)(lnA)(T-To)] (8) 因爲右手邊第一個括號內的項目具有一個負的溫度係數，右手邊第二個括號內 的項目具有一個正的溫度係數，因此，藉著調整電阻比率(R2/R1)、或是調整射 極面積比A '或是同時調整兩者，可以控制參考電壓Vref(T)使其具有正的溫度 {i數' 或是負的溫度係數。 本紙張疋度適用中国國家標準(CNS)A4規格(210X297公釐) 烴濟部中央標苹局員工福利妾®ί會印製 409452 _ _ H3_ 多數的振盪器，其頻率都是隨著操作電流而改變，對於鬆弛振盪器而言，頻率 是與電容器的充放電流有關。而對於環狀振盪器而言，頻率是與反向器的延遲 時間有關，且延遲時間又與反向器的直流工作電流有關《對於這樣的振盪器， 當溫度改變時，其工作電流必須維持恆定以保持穩定的輸出頻率。如果這些電 流是由一個電流源所產生的，則在操作溫度區間，電流源輸出的電流穩定性是 非常重要的。 圖3.是以電壓對電流轉換器作爲電流源，一個控制電壓Vin施加到運算放大器 OP1的非反向輸入端，OP1的輸出端連接到一涸MOSFET M3的閘極、以及OP1 的反向輸出端；OP1的反向輸出端係藉著一個電阻Rm連接至接地，因爲兩個 輸入端的虛擬接地電位是相等的，所以，通過Rin的電流會是Vm/Rin，且等於 M3的汲極電流；此一汲極電流構成一個電流源。 圖4.是一個典型的電壓控制的鬆驰振盪器VC〇 ’運算放大器OP2具有來自於 電壓分壓器R2與R1的正回饋，如此，構成一個史密特觸發器，藉著在反向輸 出端的電容器C之充電與放電過程，得以產生方波。這個充放電流是由一個包 含有運算放大器ΟΠ、電阻Rin、以及一個MOSFET M3所構成電壓對電流轉換 器之電流源I所鏡像形成，如圖三所示。當VI是高電位時、傳輸閘M9以及Ml 1 是導通的、且傳輸閘M8以及M10是斷路的時候，汲極電流I藉著鏡電流源M4 以及M5鏡像到MOSFHT Ml而對電容器C充電。汲極電流I藉著鏡電流源M7而 鏡像到M0SFET M2，以將電容器C放電之。[MOSFET M6使用於鉗住M3以及M4 的汲極使其汲極工作電流操作於飽和區]。當輸出電壓VI是正的時候，且當電 容器的跨電壓Vc達到史密特觸動器的臨界電壓時，VI會切換狀態。充電時間 以及放電時間構成振盪器的振遷週期且反比於電流I。若要獲得固定頻率，則 電流I就必須保持恆定。 電流1等於Vin/Rin，在一個積體電路中’電阻Rin是由半導體所製作的，而半 導體材料是具有正溫度係數的。假設Rin在溫度T時有下述關係： Rin(T) = Rin (T〇)[l+ «(Τ-Το)] (9) 當方程式(8)所表示的參考電壓等於： Vref(T) = Vbe(To)[l+α (Τ-Το)] (10) 由方程式(9)與〇0)可以衍生出維持定電流Ι(Τ) = Vref (T)/Rin(T)的條件。 a = [(k/q)(R2/Rl)(lnA).0.002]/Vbel(To) ⑴） 藉著調整電阻比値R2/R1、A、或是Vbel(To) ’也可以同時調整，可以獲得不 受溫度影響的恆定電流。 Vref可以放大或是衰減，以便在VC0中獲得適當的控制電壓。 本紙張尺度適用中團S家標準(CNS)A4規格(210X297公釐) 經濟部中夬標準局員工福利委员會印氣 409452 H3 5 圖5.是一個環狀振盪器基本結構，用以在vco中獲得適當的控制電壓，其具有 N倍奇數個反向器串聯在一起。振盪器頻率等於： fosc = 1/(2Ν τ inv) 其中的Γ inv是每一級的延遲時間，其反比於電晶體的跨導脚·而gm正比於反 向器的直流汲極電流之平方根。因此，若是反向器經由一個定電流源輸入定電 流時，振盪頻i可以保持一定。如圖3所示 圖6a.是一個電壓控制的環狀振盪器，其使^差動式的反向器。圖6b.是具有 電流源IB的差動式反向器。電流源在不同的溫度中1可以被控制並且維持 恆定，猶如在前面所述之電壓控制的鬆弛振盪器使用的溫度補償。 使用可程式控制電壓緩衝器或是單一增益電壓緩衝器的輸出電壓來產生一個控 制電壓，以便控制電壓控制振盪器VC0，分別如圖la以及圖lb所示。VC0依據 控制電壓的輸出，產生相關的頻率輸出。可程式電壓緩衝器容許系統重新調整 內部的操作頻率至最佳狀況。在一個PC系統中，主要的工作是在中央處理單元 (central processing unit, CPU)、以及快取隨機存取自己憶體(Cache RAM)中執 行。基本輸出入系統(Basic Input Output System, BIOS)可以控制可程式電壓 緩衝器使其增加操作頻率’以達到PC系統中最佳工作狀況。另一方面，如果PC 系統執行較多數的週邊輸出以及輸入的工作，則BIOS藉著可程式控制電壓緩 衝器，而可以降低CPU系統頻率，如此，可以達到較佳的穩定度以及可靠度。 否則，CPU可能過熱。降低CPU的操作速度，可以冷卻CPU也提高系統的可靠 度。 本發明也可以進一步地利用熔絲修正技術修改R2/R1的比値，而達到較高的準 確度。VCO可以是傳統的環狀振盪器、鬆驰振盪器...等，端視系統的需要而 定。 前述描述雖僅是應用於環狀振盪器、以及鬆弛振盪器，然而’本發明所揭露的 溫度補償技巧的運用，並不限制於這兩種振盪器。技巧就是，可以用於：凡是 需要正的溫度係數以及負的溫度係數作爲溫度補償的電路，以便獲得一個不隨 改變的恆定電流源。 本紙張尺度適用中國國家標準(CNS)A4規格(210 X 297公釐)409452 A7 B7 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (1) Autonomous frequency generation circuit 1. Abstract The frequency of the integrated circuit oscillator can be maintained fixed without being affected by temperature changes. Achieved by temperature compensation design. A voltage-controlled oscillator with temperature-sensitive elements must have a temperature-dependent voltage control element for temperature compensation. When the operating current is kept constant, the frequency of many types of oscillators such as relaxation oscillators and ring oscillators can be kept constant. The operating current is usually generated by a current source and is a voltage-to-current converter that generates a current whose magnitude is equal to the voltage to resistance ratio. Because semiconductor resistors have a primary temperature coefficient, a control voltage with a positive temperature coefficient is usually used to generate a current source that does not change with temperature. The positive temperature coefficient can be taken from the difference between the two forward biased pn junction voltages. The magnitude of the number depends on the size of the Pn junction. This number can also be further amplified or attenuated. 2. Background Description The present invention relates to a frequency generator, and particularly to a clock generator of an integrated circuit. Multi-frequency processing systems are becoming more and more popular in recent VLSI system applications. In these applications, an external clock source is usually used to generate the required signal frequency generation source. An external clock source requires a quartz oscillator. This will increase the package pin count of the integrated circuit and increase the layout area of the printed circuit board to provide the space occupied by the external clock source. From the perspective of a system product, the increase in stray capacitance of an external clock source will reduce the integrity of the clock signal and the characteristics of high-frequency operation. At the same time, the added circuit will also increase the high-frequency electromagnetic radiation and interleaving interference between signals. Therefore, the use of an external clock source not only increases system cost, but also reduces product features such as slower speeds and increased electrical and magnetic interference ... In the past few years, the functionality of personal computers has improved a lot due to the increased processing speed and accuracy of PC mother boards. Most of the clock timing sources used by traditional motherboards use a "phase-locked loop" (PLL) and a clock generator integrated circuit. Typically, this clock source uses a 14.318 MHz quartz oscillator as the timing reference. Because the quartz oscillator must be close to the “phase-locked loop” chip, it must occupy an area on the printed circuit board, and it will also radiate electromagnetic waves to increase signal processing interference and interleaved noise. The general design is to integrate a relaxation oscillator or ring oscillator into the integrated circuit of the system product. However, this design is difficult to obtain a stable frequency that is not sensitive to temperature changes. This is because when the temperature changes, The component's 値 and operating current will change. Although it is possible to use an energy band-gap voltage reference (Vref) in order to obtain a constant voltage that is not affected by temperature changes, circuit components, especially semiconductor resistors, cannot be immune to temperature changes. Affected. 3. Main object of the present invention One of the objects of the present invention is to not use external quartz so as to save the area of the integrated circuit 'and the area of the printed circuit board. Another object of the present invention is to compensate for the temperature change of the element 値 in the integrated circuit. The third object of the present invention is to reduce electromagnetic interference in a PC system and increase the integrity of the motherboard. The fourth object of the present invention is to improve the stability and reliability of the PC system. The size of this paper is in accordance with the Chinese National Standard (CNS) A4 (210X297 mm) (Please read the precautions on the back before writing this page) Printed by the 8 Welfare Committee of the Central Bureau of Competition of the Ministry of Economy 409452 ____H3 i — '~ ~ These objectives can be achieved by an autonomous frequency generation circuit inside the integrated circuit. A voltage supply that changes the output voltage with temperature changes is used as a voltage-controlled oscillator in order to obtain a stable frequency. . The power supply is connected with a positive temperature coefficient voltage and a bin temperature coefficient voltage in series. The negative temperature coefficient voltage is derived from the forward bias of the PN junction, and the positive temperature coefficient voltage is derived from the voltage difference between two forward biased interfaces operating at different current densities. When the positive coefficient voltage exceeds the negative temperature coefficient voltage, the control voltage has a positive temperature coefficient, and vice versa. '— A programmable voltage buffer (or single gain buffer buffer) provides an adjustable control of the reference voltage, a "voltage-controlled oscillator" [voltage-controlled oscillators VCO], according to the output of the control voltage , Can produce a mapped frequency output. The oscillator used in the present invention may be a slack oscillator, a ring oscillator, or other oscillators suitable for use in integrated circuits. Using the resistance of a voltage-controlled current source with the same temperature coefficient, the operating current can be kept constant by making up for its positive temperature coefficient. 4. Graphical illustration Figure la. Is a block diagram of the autonomous frequency generating circuit of the present invention, using a programmable voltage buffer. Figure lb. is a block diagram of the present invention using a fixed gain voltage buffer. Figure 2. Power supply with variable temperature coefficient. Figure 3. A voltage-to-current converter as a current source. Figure 4. A voltage controlled slack oscillator. Figure 5. A ring shaper. Figure 6a. Is a voltage controlled ring oscillator. Figure 6b. Current source for a ring oscillator. 5. Detailed description of the present invention Fig. La. Is a block diagram of an autonomous frequency generating circuit of the present invention using a programmable voltage buffer; Fig. Lb. is a block diagram of a fixed gain voltage buffer of the present invention. A voltage controlled oscillator obtains a frequency that is insensitive to temperature changes by controlling a reference voltage with a predetermined temperature coefficient. Figure 2. Power supply with variable temperature coefficient. Two identical MOSFETs Q3 and Q4, whose source is connected to a negative power supply Vss, and whose gate is connected to the output terminal of the “operational amplifier” (0P). The drain of Q3 is connected to the inverting input A of the operational amplifier through a resistor 汜 and the emitter of a bipolar transistor (BJT) Qb. The drain of Q4 is connected to a resistor R2, Connected to the non-inverting input terminal B of the operational amplifier, and connected to the emitter Q2 of the bipolar transistor through the resistor R1. The bases of Q1 and Q2 are connected to the common pole, and the collector is connected to the positive power supply VDD. Q4 acts as a reverser and uses the emitter interface of R2 + RHQ2 as a load '. At the non-inverting input terminal B, a negative feedback voltage will be generated. Due to the characteristics of the virtual ground of the operational amplifier, the voltages at points A and B Must be the same, the drain current of Q3 and Q4 must be the same and equal to I. The emitter region Ae2 of Q2 is A times the emitter region Ael of Q1. When the base-emitter junction voltage drops of Q1 and Q2 are For this paper size, the Chinese National Standard (CNS) A4 specification (210X297 mm) is printed by the Central Bureau of Standards of the Ministry of Economic Affairs * 5 and printed by 409452 H3 — ~ ^ and Vbe2, the pressure drop of IR1 will be Vbel-Vbe2, also That is: I = (Vbel-Vbe2) / Rl (1) At the same time, the output voltage Vref will be: Vref = -Vbel- (Vbel-Vbe2) R2 / RI. (2) The emitter current of BJT is: V Ie = Ae J〇 [exp. (Q Vbe / kT) -1] (3) where Jo is the saturation current density and is proportional to Γ2 3qVg / kT. Q is the charge = 1.6 * 1〇_19 Coulomb k is the Bozman constant = 1.38 * 10_23J / ° KT is the absolute temperature. K. In order to maintain the constant Q1 emitter current at different temperatures, the equation (3) is differentiated and set to zero to obtain the temperature change (Δ (Tl) The required change (AVljel): △ Vbel / Z \ T = -2mV / ° K (4) When any temperature T is higher than the reference temperature T, the relative VbelCD will be: Vbel (T) = Vbel (T0) -0.002 (TT〇) (5) Therefore, Vbe has a negative temperature coefficient. In addition, the following calculation results can be obtained from equations (1) and (2): IRI = (Vbe 1-Vbe2) = (kT / q) [ln (I / Ae 1) -ln (I / Ae2)] = (kT / q) lnA ⑹ The current H (kT / q) lnA] Rl is proportional to T. The voltage drop of R2 is positive Temperature coefficient IR2 = (R2 / Rl) (kT / q) lnA (7) The reference voltage becomes: Vref (T) =-[Vbel (To) -0.002 (T-To)]-[(R2 / Rl) ( k / q) (lnA) (T-To)] (8) Because the item in the first bracket on the right-hand side has a negative temperature coefficient, and the item in the second bracket on the right-hand side has a positive temperature coefficient, so By adjusting the resistance ratio (R2 / R1), or adjusting the emitter area ratio A ', or adjusting both, the reference voltage Vref (T) can be controlled to have a positive temperature {i number' or negative Temperature coefficient. This paper is compliant with China National Standard (CNS) A4 specification (210X297 mm) Employee Benefits of the Central Bureau of Standards of the Ministry of Hydrocarbons, and will be printed 409452 _ _ H3_ more The oscillator frequency is varied with the operating current for the relaxation oscillator, the frequency is related to charge and discharge current of the capacitor. For a ring oscillator, the frequency is related to the delay time of the inverter, and the delay time is related to the DC operating current of the inverter. "For such an oscillator, when the temperature changes, its operating current must be maintained. Constant to maintain a stable output frequency. If these currents are generated by a current source, the current stability of the current source output is very important during the operating temperature range. Figure 3. A voltage-to-current converter is used as the current source. A control voltage Vin is applied to the non-inverting input of the operational amplifier OP1. The output of OP1 is connected to the gate of a MOSFET M3 and the reverse output of OP1. The reverse output of OP1 is connected to ground through a resistor Rm. Because the virtual ground potentials of the two inputs are equal, the current through Rin will be Vm / Rin and equal to the drain current of M3; This sink current constitutes a current source. Figure 4. A typical voltage-controlled slack oscillator VC0 'op amp OP2 has positive feedback from voltage dividers R2 and R1. In this way, a Schmitt trigger is formed, which is During the charging and discharging process of the capacitor C at the terminal, a square wave can be generated. This charging and discharging current is formed by a current source I including a voltage-to-current converter consisting of an operational amplifier 0Π, a resistor Rin, and a MOSFET M3, as shown in Figure 3. When VI is high, transmission gates M9 and Ml 1 are on, and transmission gates M8 and M10 are open, the drain current I is charged to capacitor C by mirror current sources M4 and M5 mirrored to MOSFHT M1. The sink current I is mirrored to M0SFET M2 by the mirror current source M7 to discharge the capacitor C. [MOSFET M6 is used to clamp the drains of M3 and M4 so that their drain operating current operates in the saturation region]. When the output voltage VI is positive, and when the capacitor's trans-voltage Vc reaches the critical voltage of the Schmitt actuator, VI switches state. The charging time and the discharging time constitute the oscillation period of the oscillator and are inversely proportional to the current I. To obtain a fixed frequency, the current I must be kept constant. The current 1 is equal to Vin / Rin. In an integrated circuit, the 'resistance Rin is made of a semiconductor, and the semiconductor material has a positive temperature coefficient. Assume that Rin has the following relationship at temperature T: Rin (T) = Rin (T〇) [l + «(Τ-Το)] (9) When the reference voltage represented by equation (8) is equal to: Vref (T) = Vbe (To) [l + α (Τ-Το)] (10) The conditions for maintaining a constant current I (T) = Vref (T) / Rin (T) can be derived from equations (9) and 0). a = [(k / q) (R2 / Rl) (lnA) .0.002] / Vbel (To) ⑴) By adjusting the resistance ratio 値 R2 / R1, A, or Vbel (To) ', it can also be adjusted at the same time, It is possible to obtain a constant current independent of temperature. Vref can be amplified or attenuated to obtain the proper control voltage in VC0. This paper size is applicable to the China National Standard (CNS) A4 specification (210X297 mm). The Employee Welfare Committee of the China Standards Bureau of the Ministry of Economic Affairs, India Gas 409452 H3 5 Figure 5. The basic structure of a ring oscillator, used in vco An appropriate control voltage is obtained, which has N times an odd number of inverters connected in series. The oscillator frequency is equal to: fosc = 1 / (2N τ inv) where Γ inv is the delay time of each stage, which is inversely proportional to the transconductance pin of the transistor, and gm is proportional to the square root of the DC drain current of the inverter. Therefore, if the inverter inputs constant current through a constant current source, the oscillation frequency i can be kept constant. As shown in Figure 3 Figure 6a. Is a voltage-controlled ring oscillator, which uses a differential inverter. Figure 6b. Differential inverter with current source IB. The current source 1 can be controlled and maintained constant at different temperatures, just like the temperature compensation used in the voltage controlled relaxation oscillator described above. The output voltage of a programmable voltage buffer or a single gain voltage buffer is used to generate a control voltage in order to control the voltage-controlled oscillator VC0, as shown in Figures 1a and 1b, respectively. VC0 generates the relevant frequency output based on the output of the control voltage. Programmable voltage buffers allow the system to readjust the internal operating frequency to optimal conditions. In a PC system, the main work is performed in the central processing unit (CPU) and cache random access cache memory. The Basic Input Output System (BIOS) can control a programmable voltage buffer to increase its operating frequency ’to achieve the best working conditions in a PC system. On the other hand, if the PC system performs a large number of peripheral output and input tasks, the BIOS can reduce the CPU system frequency by programmably controlling the voltage buffer. In this way, better stability and reliability can be achieved. Otherwise, the CPU may overheat. Reducing the operating speed of the CPU can cool the CPU and increase the reliability of the system. The present invention can further use the fuse correction technology to modify the ratio R2 / R1 to achieve a higher accuracy. VCOs can be traditional ring oscillators, relaxation oscillators, etc., depending on the needs of the system. Although the foregoing description is only applied to ring oscillators and relaxation oscillators, the application of the temperature compensation technique disclosed in the present invention is not limited to these two oscillators. The trick is that it can be used for any circuit that requires a positive temperature coefficient and a negative temperature coefficient as temperature compensation in order to obtain a constant current source that does not change. This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)