201219795 六、發明說明： 【發明所屬之技術領域】 本發明疋有關於-種電壓偵測電路，且特別是有關於 偵測帶隙電路所產生之參考電壓的_種電壓偵測電路。 【先前技術】 大多數的類比電路都需要參考用的電壓、電流，或是 「時間」。參考電壓提供-個可供比較的標準，如穩壓器 _ (Regulator)的輸出電壓準位的高或低、電池充電器的開與 關等’都是依據參考電壓源或參考電流源來決定 。近年來， 由於製程的進步，以及環保的需求，使得系統操作電壓不 斷地下降，舊式的各種參考電壓線路逐一失效。 帶隙（Bandgap)參考電壓係由 National Semiconductor 的Robert Widlar^撕年發表之後，隨即成為積體電路 重要的參考電壓來源。帶隙參考電壓具有許多優點，諸如 低消耗功率及低輸出電壓。典型的帶隙參考電壓源輸出電 #壓約為1.2V〜1.25V。多數的穩壓IC多以帶隙參考電壓作 為内部的參考電壓來源。由於在參考電壓完成準備之前， 許多依賴參考電壓的電路都無法正確工作，因此通常會採 用電壓偵測電路來偵測參考電壓是否完成準備。 如第1圖所繪不傳統的參考電壓偵測電路之電路圖， 傳統上參考電壓債測電路通常是以_N通道金氧半場效應 電晶體107來實現，其係利用金氧半場效應電晶體1〇7本 身的臨界電壓(Threshold VGltage)，來決定是否觸發下一級 201219795 的電路。在此第1圖當中，A點上為原始參考電壓，8點 上則為經過低通濾波器101濾波的參考電壓，其中低通減 波器101係由電阻103與電容105所組成。當B點上經^ 波後的參考電壓的電壓準位達到N通道金氧半場效應電晶 體107的臨界電壓時’會觸發下一級的電路。然而，若B 點上濾波後參考電壓的上升時間因為低通濾波器101而產 生過大延遲，導致過早觸發下一級的電路，則之後的電路 都將失誤。 因此需要一種新的電壓偵測電路，能夠正確地債測參 考電壓是否已準備完成，避免因其延遲時間過長而無法正 確地判讀濾波後參考電壓的電壓準位，進而消除電路誤動 作的狀況。 【發明内容】 因此，本發明之一態樣提供一種電壓偵測電路，能夠 精準地偵測濾波後參考電壓是否已準備完成，以消除電路 誤動作的狀況；更可設定濾波後參考電壓的觸發狀態而不 需要額外的參考信號。 依據本發明之一實施例，電壓偵測電路係偵測一原始 參考電壓與一濾波後參考電壓兩者之間的差距，此電壓偵 測電路含有一差動輸入對與一調變電阻。差動輸入對具有 兩輸入端電性連接低通濾波器，以分別接收原始參考電壓 與濾波後參考電壓。調變電阻電性連接差動輸入對，其中 當調變電阻上的壓降等於原始參考電壓與濾波後參考電壓 201219795 兩者之間的電位差時，此電壓偵測電路會輸出一電壓備妥 信號，代表濾波後參考電壓已穩定。 本發明之另一態樣是在提供一種參考電壓產生偵測 器’能夠精準地偵測濾波後參考電壓是否已完成準備，以 消除電路誤動作的狀況；更可設定濾波後參考電壓的觸發 狀態而不需任何需額外的參考信號。 依據本發明之另一實施例，參考電麼產生 <貞測器係產 生一濾波後參考電壓，並偵測此濾波後參考電壓之電壓準 #位，此參考電壓產生偵測器含有一參考電壓產生電路、一 低通濾波器濾波、一差動輸入對，以及一調變電阻。參考 電壓產生電路用以產生一原始參考電壓’低通濾波器濾波 原始參考電壓來產生一濾波後參考電壓。差動輸入對具有 兩輸入端電性連接低通濾波器，以分別接收參考電壓與濾 波後參考電壓。調變電阻電性連接差動輸入對，其中，當 調變電阻上的壓降等於原始參考電壓與濾波後參考電壓兩 者之間的電位差時，電壓偵測電路會輸出一電壓備妥信 • 號’代表濾波後參考電壓已經穩定。 以上實施例之電壓偵測電路與參考電壓產生偵測器’ 能夠精準地偵測濾波後參考電壓是否已完成準備，消除電 路誤動作的狀況；亦可設定濾波後參考電壓的觸發狀態， 而不需要任何額外的參考信號。 【實施方式】 請參照第2圖’其係繪示本發明一實施方式參考電壓 201219795 產生偵測器之電路圖。參考電壓產生偵測器200產生一濾 波後參考電壓，並偵測此濾波後參考電壓之電壓準位，此 參考電壓產生偵測器200主要含有參考電壓產生電路 201、低通濾波器203，以及電壓偵測電路205，其中低通 濾波器203與電壓偵測電路205以額外的硬體來單獨製 作；亦可直接取自於類比積體電路中的比較器電路，而不 需要增加額外的硬體。 參考電壓產生電路201，例如帶隙(Bandgap)參考電壓 •產生電路，用來產生原始參考電壓。低通濾波器203則濾 波原始參考電壓來產生濾波後參考電壓，此低通濾波器2〇3 含有濾波電阻215與第一電容217，其中濾波電阻215之 第一端接收原始參考電壓，第一電容217的第一端電性連 接濾波電阻215之第二端來提供濾波後參考電壓，第一電 容217的第二端則電性連接至接地端。 參考電壓產生偵測器200的電壓偵測電路2〇5主要包 含調變電阻209與差動輸入對2〇7，其中調變電阻2〇9係 籲電性連接至差動輸人對2G7。差動輸人對2G7具有 端電性連接低通濾、波器203,以分別接收原始參 慮波後參考電壓。更具體地說，差動輸入對2〇7係由^ 道的第-電晶體219以及P通道的第二電晶體22 = 成；其中’第-電晶體219之閘極接收原始參考，、: 極則電性連接調變電阻期之第_端；第二電晶體= 閉極電性連接低通遽波器2〇3來接收爐波後參考電壓，= 源極則電性連接調變電阻209之第二端。 ” 調變電阻209的電阻值R可依據原始參考電壓與遽波 201219795 後參考電壓兩者的差距來調整，此電阻值的範圍約略為使 得調變電阻209上的壓降範圍落在5〇11^至1〇〇mV。當調 變電阻209上的壓降(V=IxR)等於原始參考電壓與滤波後 參考電壓兩者之間的電位差時，電壓偵測電路2〇5會輸出 一電壓備妥信號，代表濾波後參考電壓已經穩定，可供下 級電路來使用。因此，若濾、波後參考電壓的電壓準位需要 十分接近原始參考電壓的電壓準位，則可選擇電阻值較 小、電愿降較小的調變電阻209來產生電壓備妥信號。 • 更詳細來說，當A點上原始參考電壓與B點上濾波後 參考電壓的電壓準位差距小於調變電阻209上的壓降時 (IR)，代表濾波後參考電壓與原始參考電壓兩者的電壓準 位已十分接近’此時第一電晶體219與第二電晶體221上 會流過大小約略相等的電流，而輸出電壓備妥信號。另一 方面’若是B點上濾波後參考電壓的電壓準位遠小於A點 上原始參考電壓的電壓準位，則大部分的電流僅流過第二 電晶體221，因此使得電壓備妥信號之電壓準位拉低，不 0 輸出電壓備妥信號。 除了調變電阻209與差動輸入對207以外，參考電壓 產生偵測器200的電壓偵測電路205更含有第一電流鏡電 路211與第二電流鏡電路213。 第一電流鏡電路211電性連接差動輸入對207之第二 電晶體221，來提供第二電晶體221第一定電流（端點C上 的電流I) ’此第一電流鏡電路211具有n通道的第三電晶 體223與第四電晶體225。第三電晶體223之汲極電性連 接第二電晶體221之汲極，第三電晶體223之源極電性連 201219795 接接地端。第四電晶體225之閘極電性連接第三電晶體 之閘極，第四電晶體225之源極則電性連接至接。223 第二電流鏡電路213電性連接差動輸入對2 ’ 第 ~.201219795 VI. Description of the Invention: [Technical Field] The present invention relates to a voltage detecting circuit, and more particularly to a voltage detecting circuit for detecting a reference voltage generated by a bandgap circuit. [Prior Art] Most analog circuits require reference voltage, current, or "time". The reference voltage provides a comparable standard, such as the high or low output voltage level of the regulator (Regulator), the battery charger's on and off, etc. are determined by the reference voltage source or the reference current source. . In recent years, due to the progress of the process and the demand for environmental protection, the operating voltage of the system has been continuously reduced, and the old various reference voltage lines have failed one by one. The Bandgap reference voltage was published by National Semiconductor's Robert Widlar^ and became an important reference voltage source for integrated circuits. The bandgap reference voltage has many advantages, such as low power consumption and low output voltage. A typical bandgap reference voltage source output voltage is approximately 1.2V to 1.25V. Most regulator ICs use the bandgap reference voltage as the internal reference voltage source. Since many circuits that rely on the reference voltage do not work properly until the reference voltage is ready, a voltage detection circuit is usually used to detect if the reference voltage is ready. As shown in Fig. 1, the circuit diagram of the conventional reference voltage detecting circuit is conventionally implemented. The conventional reference voltage measuring circuit is usually implemented by a _N channel MOS field effect transistor 107, which utilizes a gold oxide half field effect transistor 1 〇7's own threshold voltage (Threshold VGltage) to determine whether to trigger the next level of 201219795 circuit. In Fig. 1, the original reference voltage is at point A, and the reference voltage filtered by low-pass filter 101 is at 8 o'clock. The low-pass filter 101 is composed of a resistor 103 and a capacitor 105. When the voltage level of the reference voltage after the wave at point B reaches the threshold voltage of the N-channel MOS field-effect transistor 107, the next-stage circuit is triggered. However, if the rise time of the reference voltage after filtering at point B causes an excessive delay due to the low-pass filter 101, causing the circuit of the next stage to be triggered prematurely, the subsequent circuits will be missed. Therefore, a new voltage detection circuit is needed to correctly determine whether the reference voltage is ready to be completed, and to avoid correcting the voltage level of the filtered reference voltage due to its long delay time, thereby eliminating the malfunction of the circuit. SUMMARY OF THE INVENTION Accordingly, an aspect of the present invention provides a voltage detecting circuit capable of accurately detecting whether a filtered reference voltage is ready to be completed to eliminate a malfunction of a circuit, and setting a trigger state of a filtered reference voltage. No additional reference signals are needed. According to an embodiment of the invention, the voltage detecting circuit detects a difference between an original reference voltage and a filtered reference voltage, and the voltage detecting circuit includes a differential input pair and a modulation resistor. The differential input pair has two inputs electrically connected to the low pass filter to receive the original reference voltage and the filtered reference voltage, respectively. The modulation resistor is electrically connected to the differential input pair, wherein when the voltage drop across the modulation resistor is equal to the potential difference between the original reference voltage and the filtered reference voltage 201219795, the voltage detection circuit outputs a voltage ready signal , represents that the filtered reference voltage has stabilized. Another aspect of the present invention is to provide a reference voltage generation detector that can accurately detect whether the filtered reference voltage has been prepared to eliminate the malfunction of the circuit; and can also set the trigger state of the filtered reference voltage. No additional reference signals are required. According to another embodiment of the present invention, the reference device generates a filtered reference voltage and detects a voltage reference bit of the filtered reference voltage. The reference voltage generation detector includes a reference. A voltage generating circuit, a low pass filter, a differential input pair, and a modulation resistor. The reference voltage generating circuit is operative to generate an original reference voltage ' low pass filter to filter the original reference voltage to produce a filtered reference voltage. The differential input pair has two input terminals electrically connected to the low pass filter to respectively receive the reference voltage and the filtered reference voltage. The modulation resistor is electrically connected to the differential input pair, wherein when the voltage drop across the modulation resistor is equal to the potential difference between the original reference voltage and the filtered reference voltage, the voltage detection circuit outputs a voltage ready signal. The number ' represents the filtered reference voltage has stabilized. The voltage detecting circuit and the reference voltage generating detector of the above embodiment can accurately detect whether the filtered reference voltage has been prepared to eliminate the malfunction of the circuit; and can also set the trigger state of the filtered reference voltage without Any additional reference signals. [Embodiment] Referring to Figure 2, there is shown a circuit diagram of a detector for generating a reference voltage 201219795 according to an embodiment of the present invention. The reference voltage generation detector 200 generates a filtered reference voltage and detects the voltage level of the filtered reference voltage. The reference voltage generation detector 200 mainly includes a reference voltage generating circuit 201, a low pass filter 203, and The voltage detecting circuit 205, wherein the low pass filter 203 and the voltage detecting circuit 205 are separately fabricated with additional hardware; or directly from the comparator circuit in the analog integrated circuit, without adding extra hard body. A reference voltage generating circuit 201, such as a bandgap reference voltage generating circuit, is used to generate an original reference voltage. The low pass filter 203 filters the original reference voltage to generate a filtered reference voltage. The low pass filter 2〇3 includes a filter resistor 215 and a first capacitor 217, wherein the first end of the filter resistor 215 receives the original reference voltage, first The first end of the capacitor 217 is electrically connected to the second end of the filter resistor 215 to provide a filtered reference voltage, and the second end of the first capacitor 217 is electrically connected to the ground. The voltage detecting circuit 2〇5 of the reference voltage generation detector 200 mainly includes a modulation resistor 209 and a differential input pair 2〇7, wherein the modulation resistor 2〇9 is electrically connected to the differential input pair 2G7. The differential input has a terminal electrically connected to the low pass filter and the wave 203 to receive the reference wave after the original reference wave. More specifically, the differential input pair 2〇7 is formed by the first transistor 219 of the channel and the second transistor 22 of the channel P; wherein the gate of the first transistor 219 receives the original reference, The pole is electrically connected to the _th terminal of the modulation resistance period; the second transistor = the closed pole is electrically connected to the low-pass chopper 2〇3 to receive the reference voltage after the furnace wave, and the source is electrically connected to the modulation resistor The second end of 209. The resistance value R of the modulation resistor 209 can be adjusted according to the difference between the original reference voltage and the reference voltage after the chopping 201219795. The range of the resistance value is approximately such that the voltage drop range of the modulation resistor 209 falls within 5〇11. ^ to 1〇〇mV. When the voltage drop across the modulation resistor 209 (V=IxR) is equal to the potential difference between the original reference voltage and the filtered reference voltage, the voltage detection circuit 2〇5 outputs a voltage reserve. The signal is representative, and the reference voltage after filtering is stable, which can be used by the lower-level circuit. Therefore, if the voltage level of the reference voltage after filtering and wave needs to be very close to the voltage level of the original reference voltage, the resistance value can be selected to be small. The power is expected to drop the smaller modulation resistor 209 to generate a voltage ready signal. • In more detail, when the original reference voltage at point A and the filtered reference voltage at point B are not smaller than the voltage on the modulation resistor 209 At the time of voltage drop (IR), it is represented that the voltage level of both the filtered reference voltage and the original reference voltage is very close to 'the current transistor 219 and the second transistor 221 will flow approximately the same amount of current, and Output On the other hand, if the voltage level of the reference voltage after filtering at point B is much smaller than the voltage level of the original reference voltage at point A, most of the current flows only through the second transistor 221, thus making The voltage level of the voltage ready signal is pulled low, and the output voltage is not ready. In addition to the modulation resistor 209 and the differential input pair 207, the voltage detecting circuit 205 of the reference voltage generating detector 200 further includes a first current. The mirror circuit 211 and the second current mirror circuit 213. The first current mirror circuit 211 is electrically connected to the second transistor 221 of the differential input pair 207 to provide a first constant current of the second transistor 221 (current at the terminal C) I) 'The first current mirror circuit 211 has an n-channel third transistor 223 and a fourth transistor 225. The third transistor 223 is electrically connected to the drain of the second transistor 221, the third transistor The source of 223 is connected to the ground terminal of 201219795. The gate of the fourth transistor 225 is electrically connected to the gate of the third transistor, and the source of the fourth transistor 225 is electrically connected to the connection. The mirror circuit 213 is electrically connected to the differential input pair 2 ' ~.
電晶體219、調變電阻209以及第一電流鏡電路211 , 供第一電晶體219、調變電阻2〇9以及第一電流鏡電路2二 第二定電流(E點上流過的電流21)與第三定電流(D點上流 過的電流I)。第二電流鏡電路213主要由兩個電晶體227 與一個電晶體229等三顆電晶體所組成，其中電晶體229 的面積可為電晶體227面積的兩倍，來提供兩倍於電晶體 227的電流（即21)，此兩倍之電流再由第一電晶體219與第 二電晶體221來分配。 以上實施例之电魘1貝凋冤路與參考電壓產生偵測器， 能夠精準地偵測慮波後參考電壓是否已完成準備，消除電 路誤動作的狀況，而不需任何需加入額外的參考信號；亦 可根據所需要的電壓準位的精準度，來調整調變電阻的電 阻值，以彈性地設定濾波後參考電壓_發狀離。 雖然本發明已以實施方式捤， 者，在㈣離本發明之精⑹彳領域+具有通常知諸 與潤飾，因此本發明之保&圍内，當可作各種之更鸯 所界定者為準。 °軏圍當視後附之申請專利範屋 【圖式簡單說明】 特徵、優點與實施例 為讓本發明之上述和|他 201219795 能更明顯易懂，所附圖式之說明如下： 第1圖係繪示傳統的參考電壓偵測電路之電路圖。 第2圖係繪示本發明一實施方式參考電壓產生偵測器 之電路圖。 【主要元件符號說明】The transistor 219, the modulation resistor 209, and the first current mirror circuit 211 are provided for the first transistor 219, the modulation resistor 2〇9, and the first current mirror circuit 2 to have a second constant current (current 21 flowing through point E). And the third constant current (current I flowing at point D). The second current mirror circuit 213 is mainly composed of three transistors 227 and one transistor 229, wherein the area of the transistor 229 can be twice the area of the transistor 227 to provide twice the size of the transistor 227. The current (i.e., 21) is again distributed by the first transistor 219 and the second transistor 221. In the above embodiment, the electric 魇1 冤 冤 与 and reference voltage generation detector can accurately detect whether the reference voltage after the wave has been prepared, and eliminate the malfunction of the circuit without any need to add an additional reference signal. The resistance value of the modulation resistor can also be adjusted according to the accuracy of the required voltage level to elastically set the filtered reference voltage _ hair-off. Although the present invention has been described in the above embodiments, it is generally known and retouched in the field of (6) from the fine (6) of the present invention, and therefore, it can be defined as a variety of quasi. 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 The figure shows the circuit diagram of a conventional reference voltage detection circuit. Fig. 2 is a circuit diagram showing a reference voltage generation detector according to an embodiment of the present invention. [Main component symbol description]
101 ： 低通濾波器 103 ： 電阻 105 ： 電容 107 : N通道金氧半場效應電晶體 200 ： 參考電壓產生偵測器 201 ： 參考電壓產生電路 203 ： 低通遽波器 205 ： 電壓偵測電路 207 : 差動輸入對 209 ： 調變電阻 211 ： 第一電流鏡電路 213 ： 第二電流鏡電路 215 ： 濾波電阻 217 ： 第一電容 219 ： 第一電晶體 221 ： 第二電晶體 223 ： 第三電晶體 225 ： 第四電晶體 227 ： 電晶體 229 ： 電晶體101 : Low pass filter 103 : Resistor 105 : Capacitor 107 : N channel MOS half field effect transistor 200 : Reference voltage generation detector 201 : Reference voltage generation circuit 203 : Low pass chopper 205 : Voltage detection circuit 207 : Differential input pair 209 : Modulation resistor 211 : First current mirror circuit 213 : Second current mirror circuit 215 : Filter resistor 217 : First capacitor 219 : First transistor 221 : Second transistor 223 : Third battery Crystal 225 : Fourth transistor 227 : transistor 229 : transistor