Ultra-low power bandgap reference start-up circuit

Abstract

The application discloses a kind of ultra-low power consumption band gap reference starting circuit, it includes respectively with power supply voltage connection current generating unit, first bias voltage generating unit and second bias voltage generating unit;The current generating unit is used to generate nA level current and generate the starting voltage of the first bias voltage generating unit, the first bias voltage generating unit is started according to the starting voltage provided by the current generating unit and generates first bias voltage, the first bias voltage is output to second bias voltage generating unit;The second bias voltage generating unit is started with the first bias voltage as starting voltage and generates second bias voltage;The first bias voltage and the second bias voltage are all output to band gap reference circuit to start the band gap reference circuit.The ultra-low power consumption band gap reference starting circuit of the application can normally start nA level band gap reference circuit, and the working current of starting circuit is also nA level, reduce power consumption, save cost.

Description

Technical Field

[0001] This invention relates to the field of integrated circuits, and more specifically to an ultra-low power bandgap reference startup circuit. Background Technology

[0002] With the widespread adoption and continuous iteration of portable electronic products in the market, the requirements for chip power consumption and performance are becoming increasingly stringent. As a fundamental component of integrated circuits, bandgap reference circuits are an unavoidable part of applications with varying product requirements.

[0003] To achieve ultra-low power consumption, ultra-low power bandgap reference circuits require high impedance to reduce operating current compared to traditional bandgap reference circuits. This can usually be achieved simply by adding a series of resistors directly into the bandgap reference circuit. However, in bandgap reference circuits with operating current in the nA range, this structure of directly adding a series of resistors to reduce operating current cannot stably drive and maintain the normal operation of the bandgap reference circuit, affecting its operation and further impacting the overall chip performance.

[0004] Therefore, it is necessary to provide an improved ultra-low power bandgap reference startup circuit to overcome the above-mentioned defects by starting the bandgap reference circuit normally and effectively. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-low power bandgap reference startup circuit. This ultra-low power bandgap reference startup circuit can normally start a bandgap reference circuit in the nA range, and the operating current of the startup circuit is also in the nA range, which reduces power consumption and saves costs.

[0006] To achieve the above objectives, the present invention provides an ultra-low power bandgap reference startup circuit, comprising a current generating unit and a first bias voltage generating unit respectively connected to a power supply voltage; the current generating unit generates an nA-level current and generates a startup voltage for the first bias voltage generating unit, the first bias voltage generating unit starts up according to the startup voltage provided by the current generating unit and generates a first bias voltage, and outputs the first bias voltage to the bandgap reference circuit to start the bandgap reference circuit; wherein, the first bias voltage generating unit includes a third MOSFET and a capacitor, the drain of the third MOSFET is connected to the power supply voltage, its gate is connected to the current generating unit, its source is connected to an input terminal of the bandgap reference circuit, one end of the capacitor is connected to the source of the second MOSFET, and the other end is grounded.

[0007] Preferably, the ultra-low power bandgap reference startup circuit further includes a second bias voltage generation unit. The second bias voltage generation unit is connected to the power supply voltage, the first bias voltage generation unit, and an input terminal of the bandgap reference circuit. The source of the third MOSFET is connected to the second bias voltage generation unit to input the first bias voltage to the second bias voltage generation unit. The second bias voltage generation unit starts up with the first bias voltage as the startup voltage and generates a second bias voltage, and outputs the second bias voltage to the bandgap reference circuit. Preferably, the second bias voltage generation unit includes a fourth MOSFET and a fifth MOSFET. The gate of the fourth MOSFET is connected to the source of the third MOSFET, and its source is grounded. The drain of the third MOSFET is connected to the drain of the fifth MOSFET. The source of the fifth MOSFET is connected to the power supply voltage, and its gate and drain are connected to another input terminal of the bandgap reference circuit.

[0008] Preferably, each of the inverted MOSFETs is an N-type MOSFET, and the aspect ratio is greater than 1.

[0009] Preferably, the first MOSFET, the second MOSFET, the third MOSFET, and the fourth MOSFET are all N-type MOSFETs, and the fifth MOSFET is a P-type MOSFET.

[0010] Preferably, the fifth MOS transistor and the bandgap reference circuit form a current mirror structure.

[0011] Compared with the prior art, the ultra-low power bandgap reference startup circuit of the present invention uses the nA-level current generated by the current generation unit to sequentially start the first bias voltage generation unit and the second bias voltage generation unit, and correspondingly generates the first bias voltage and the second bias voltage. The bandgap reference circuit can only be started when the second bias voltage is generated. In this startup process, the first bias voltage and the second bias voltage are generated only when the voltage value of their respective units reaches the set startup value, so that the two bias voltages generated are stable and reliable, thereby enabling the bandgap reference circuit to be started stably and reliably. Moreover, during the operation of the entire startup circuit, the operating current of the current generation unit, the first bias voltage generation unit, and the second bias voltage generation unit are all in the nA level, which also ensures that the entire startup circuit maintains an ultra-low power consumption level.

[0012] The invention will become clearer from the following description, taken in conjunction with the accompanying drawings, which are used to explain embodiments of the invention. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the ultra-low power bandgap reference startup circuit of the present invention. Detailed Implementation

[0014] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which similar element reference numerals represent similar elements. As described above, the present invention provides an ultra-low power bandgap reference startup circuit. This ultra-low power bandgap reference startup circuit can normally start a bandgap reference circuit in the nA range, and the operating current of the startup circuit is also in the nA range, thus reducing power consumption and saving costs.

[0015] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the ultra-low power bandgap reference startup circuit of the present invention. Figure 1 As shown, the ultra-low power bandgap reference startup circuit of the present invention includes a current generation unit, a first bias voltage generation unit, and a second bias voltage generation unit, which are respectively connected to the power supply voltage AVD. The current generation unit is used to generate an nA-level current and generate the startup voltage of the first bias voltage generation unit. The current generated by the current generation unit is in the nA level, and at the same time, it also provides a startup voltage to the first bias voltage generation unit, so that the power consumption of the current generation unit and the first bias voltage generation unit can be kept at a relatively low level, so as to ensure the ultra-low power consumption of the entire startup circuit. The first bias voltage generating unit starts and generates a first bias voltage based on the start-up voltage provided by the current generating unit, and outputs the first bias voltage to the second bias voltage generating unit; the second bias voltage generating unit starts and generates a second bias voltage using the first bias voltage as the start-up voltage; both the first bias voltage and the second bias voltage are output to the bandgap reference circuit to start the bandgap reference circuit; thus, the first bias voltage generating unit and the second bias voltage generating unit are started sequentially by the current generating unit, and the first bias voltage and the second bias voltage are generated accordingly, until the second bias voltage is generated before the bandgap reference circuit can be started. In this start-up process, the first bias voltage and the second bias voltage are generated only when the voltage value of their respective units reaches the set start-up value, so that the two bias voltages generated are stable and reliable, thereby enabling the bandgap reference circuit to be started stably and reliably. Furthermore, in some applications, the bandgap reference circuit only requires a bias voltage to start working normally. In such scenarios, the second bias voltage generating unit is not necessary, and the first bias voltage generated by the first bias generating unit can start the bandgap reference circuit normally. Therefore, in the application of the ultra-low power bandgap reference startup circuit of the present invention, the second bias voltage generating unit can be added or not, depending on the specific requirements of the bandgap reference circuit to be started.

[0016] Specifically, such as Figure 1As shown, the current generating unit includes a first MOSFET MN1, a second MOSFET MN2, and n inverted-ratio MOSFETs (M1, M2...Mn-1, Mn) connected in series. The drain of the first inverted-ratio MOSFET M1 is connected to the power supply voltage AVD. The source of the nth inverted-ratio MOSFET Mn is connected to the drain of the second MOSFET MN2, the drain of the first MOSFET MN1, and the gate, and is also connected to the first bias voltage generating unit to provide a startup voltage to the first bias voltage generating unit. The gate of the second MOSFET MN2 is connected to an output terminal of a bandgap reference circuit, so that the output voltage VFB of the bandgap reference circuit can further control the conduction or shutdown of the second MOSFET MN2, strengthening the feedback control effect. The sources of the first MOSFET MN1 and the second MOSFET MN2 are both grounded. In a preferred embodiment of the present invention, each of the inverted-ratio MOSFETs (M1, M2...Mn-1, Mn) is an N-type MOSFET with an aspect ratio greater than 1, thereby ensuring that the current Ia generated by the current generating unit is very small and in the nA range. In this invention, n is a natural number greater than 1. The value of n can be determined according to the actual usage requirements of the circuit. When the value of n is larger, the current generated by the current generating unit is smaller, and vice versa. Therefore, as long as the current Ia generated by the current generating unit is in the nA range, the specific current value can be flexibly selected according to the actual situation, thereby correspondingly selecting the value of n.

[0017] In addition, the first bias voltage generating unit includes a third MOSFET MN3 and a capacitor C1. The drain of the third MOSFET MN3 is connected to the power supply voltage AVD, its gate is connected to the current generating unit, and its source is connected to the second bias voltage generating unit and an input terminal of the bandgap reference circuit, so as to input the generated first bias voltage VB1 to the bandgap reference circuit. One end of the capacitor C1 is connected to the source of the second MOSFET, and the other end is grounded. In this unit, because the current generating unit is connected to the gate of the third MOSFET MN3, the voltage on the current generating unit can be used to start the third MOSFET MN3 to conduct and charge the capacitor C1. During the charging process, the voltage of the source of the third MOSFET MN3 (i.e., the first bias voltage VB1) is gradually increased. That is, under the premise that the third MOSFET MN3 is turned on, the voltage value of the first bias voltage VB1 is gradually made to reach the voltage value required by the bandgap reference circuit.

[0018] Furthermore, the second bias voltage generating unit includes a fourth MOSFET MN4 and a fifth MOSFET MP1. The gate of the fourth MOSFET MN4 is connected to the source of the third MOSFET MN3, and its source is grounded. The drain of the third MOSFET MN3 is connected to the drain of the fifth MOSFET MP1. The source of the fifth MOSFET MP1 is connected to the power supply voltage AVD, and its gate and drain are connected and connected to another input terminal of the bandgap reference circuit. In this unit, when the source voltage of the third MOSFET MN3 reaches the value of the first bias voltage VB1, the second bias voltage generating unit is activated and the fourth MOSFET MN4 is turned on, thereby causing the fifth MOSFET MP1 to generate a second bias voltage VB2, which is input to the bandgap reference circuit to cooperate with the first bias voltage VB1 to activate the bandgap reference circuit. As a preferred embodiment of the present invention, the first MOSFET MN1, the second MOSFET MN2, the third MOSFET MN3, and the fourth MOSFET MN4 are all N-type MOSFETs, and the fifth MOSFET MP1 is a P-type MOSFET to ensure that corresponding stable current and voltage can be generated. In addition, the fifth MOS transistor MP1 forms a current mirror structure with the bandgap reference circuit. The operating current of the bandgap reference circuit is in the nA range, and the fifth MOS transistor MP1 mirrors the operating current of the bandgap reference circuit, so that the current Ic on the second bias voltage generation unit where the fifth MOS transistor MP1 is located is also in the nA range, thus ensuring the ultra-low power consumption of the second bias voltage generation unit.

[0019] Please refer to the following: Figure 1 The working principle of the ultra-low power bandgap reference startup circuit of the present invention is described below:

[0020] In the initial state, the current generating unit is turned on by default, with inverting ratio MOSFETs M1 to Mn connected in series to provide a sufficiently large resistance to control the current Ia of the current generating unit to be in the nA range. For the first bias voltage generating unit, the bandgap reference circuit is not operating, and its output voltage VFB = 0, causing the second MOSFET MN2 to be in the off state. At this time, the third MOSFET MN3 is turned on by using the gate-source voltage of the first MOSFET MN1 as its gate bias voltage, and begins to charge the capacitor C1. The charging time and the magnitude of the charging current Ib of capacitor C1 can be controlled by adjusting the aspect ratio of the third MOSFET MN3 and the capacitance value of capacitor C1. In the second bias voltage generation unit, since the initial value of the first bias voltage VB1 is 0 (capacitor C1 is not charged), the fourth MOS transistor MN4 is not turned on. As the third MOS transistor MN3 turns on and charges capacitor C1, the first bias voltage VB1 gradually rises and rises to the turn-on voltage of the fourth MOS transistor MN4, thus turning on the fourth MOS transistor MN4. This enables the second bias voltage generation unit to start, and then generates a second bias voltage VB2 through the gate of the fifth MOS transistor MP1. Both the first bias voltage VB1 and the second bias voltage VB2 are input to the bandgap reference circuit to start the bandgap reference circuit into the working state. When the bandgap reference circuit is in operation, its output voltage VFB rises, turning on the second MOSFET MN2. The second MOSFET MN2 is connected in parallel with the first MOSFET MN1, which is connected in a diode configuration. All current Ia flows to the second MOSFET MN2. The n inverting transistors M1 to Mn are connected in series with the second MOSFET MN2 to divide the voltage. Since the impedance of the second MOSFET MN2 is much smaller than the total impedance of the n inverting transistors M1 to Mn in series, node A is equivalent to ground. This pulls the gate voltage of the third MOSFET MN3 down to ground, turning off the third MOSFET MN3. The first bias voltage generating unit is in a closed state and no longer charges capacitor C1. The first bias voltage VB1 no longer rises, and the second bias voltage generating unit also stabilizes. The second bias voltage VB2 no longer changes, and the bandgap reference circuit continues to operate normally.

[0021] In summary, the ultra-low power bandgap reference startup circuit of the present invention uses the nA-level current generated by the current generation unit to sequentially start the first bias voltage generation unit and the second bias voltage generation unit, and correspondingly generates the first bias voltage and the second bias voltage. The bandgap reference circuit can only be started when the second bias voltage is generated. During this startup process, the first bias voltage and the second bias voltage are generated only when the voltage value of their respective units reaches the set startup value, so that the two bias voltages generated are stable and reliable, thereby enabling the bandgap reference circuit to be started stably and reliably. Moreover, during the operation of the entire startup circuit, the operating current of the current generation unit, the first bias voltage generation unit, and the second bias voltage generation unit are all in the nA level, which also ensures that the entire startup circuit maintains an ultra-low power consumption level.

[0022] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.

Claims

1. An ultra-low power bandgap reference start-up circuit, characterized by, The current generating unit and the first bias voltage generating unit are connected with the power voltage respectively; the current generating unit is used to generate nA level current and generate the starting voltage of the first bias voltage generating unit; the first bias voltage generating unit is started according to the starting voltage provided by the current generating unit and generates the first bias voltage; the first bias voltage is output to the band gap reference circuit to start the band gap reference circuit; wherein the first bias voltage generating unit comprises a third MOS tube and a capacitor; the drain of the third MOS tube is connected with the power voltage; the gate is connected with the current generating unit; the source is connected with an input end of the band gap reference circuit; one end of the capacitor is connected with the source of the third MOS tube; the other end is grounded; the second bias voltage generating unit is further connected with the power voltage, the first bias voltage generating unit and the input end of the band gap reference circuit respectively; the source of the third MOS tube is connected with the second bias voltage generating unit to input the first bias voltage to the second bias voltage generating unit; the second bias voltage generating unit is started with the first bias voltage as the starting voltage and generates the second bias voltage; and the second bias voltage is output to the band gap reference circuit.

2. The ultra-low power bandgap reference start-up circuit of claim 1, wherein, The current generating unit comprises a first MOS tube, a second MOS tube and N number of inverse ratio MOS tubes connected in series; the drain of the first inverse ratio MOS tube is connected with the power voltage; the source of the Nth inverse ratio MOS tube is connected with the drain of the second MOS tube, the drain and the gate of the first MOS tube and connected with the first bias voltage generating unit; the gate of the second MOS tube is connected with an output end of the band gap reference circuit; the sources of the first MOS tube and the second MOS tube are grounded; and n is a natural number greater than 1.

3. The ultra-low power bandgap reference start-up circuit of claim 2, wherein, The second bias voltage generating unit comprises a fourth MOS tube and a fifth MOS tube; the gate of the fourth MOS tube is connected with the source of the third MOS tube; the source is grounded; the drain of the third MOS tube is connected with the drain of the fifth MOS tube; the source of the fifth MOS tube is connected with the power voltage; the gate and the drain are connected and connected with another input end of the band gap reference circuit.

4. The ultra-low power bandgap reference start-up circuit of claim 2, wherein, Each of the inverse ratio MOS tubes is N type MOS tube and the aspect ratio is greater than 1.

5. The ultra-low power bandgap reference start-up circuit of claim 3, wherein, The first MOS tube, the second MOS tube, the third MOS tube and the fourth MOS tube are N type MOS tubes; and the fifth MOS tube is P type MOS tube.

6. The ultra-low power bandgap reference start-up circuit of claim 3, wherein, The fifth MOS tube and the band gap reference circuit form a current mirror structure.

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