TWI730534B - Power supply circuit and digital input buffer, control chip and information processing device using it - Google Patents

Abstract

The present invention mainly discloses a power supply circuit for adjusting the working voltage to a low-dropout working voltage, thereby providing the low-dropout working voltage to a Schmitt circuit unit, so that one of the Schmitt circuit units is logic high. -high) The minimum value of the output signal can reach 1.2V, 1.1V, or 1.05V, and at the same time, the maximum value of the logic-low output signal of one of the Schmitt circuit units can reach 0.6V. In addition, when the operating voltage is adjusted to the low dropout operating voltage, it is compatible with compensating the process angle changes of N-MOSFET and P-MOSFET elements at the same time, so that the worst-case process angles SNFP and FNSP are changed to SS and FF process angles. In this way, the input switching point voltage of the Schmitt circuit unit is regulated, so that the change in the full process angle range can be effectively controlled without significant changes.

Description

Power supply circuit and digital input buffer, control chip and information processing device using it

The present invention relates to the technical field of digital input buffers, and particularly refers to a power supply circuit applied to provide a low dropout operating voltage to a Schmitt circuit unit.

The traditional Schmitt circuit is mainly composed of an operational amplifier and a plurality of resistors, a comparator circuit containing positive feedback. In terms of practical applications, operational amplifiers have the disadvantages of large size and high power consumption, so they are not conducive to application in integrated circuit chip manufacturing. In view of this, a CMOS Schmitt circuit is proposed. FIG. 1 shows the circuit topology of a conventional CMOS Schmitt circuit, and FIG. 2 is the equivalent circuit symbol of the conventional CMOS Schmitt circuit. As shown in FIG. 1, the conventional CMOS Schmitt circuit 2 includes: a first P-type MOSFET element 2M1, a second P-type MOSFET element 2M2, a first N-type MOSFET element 2M3, and a second N-type MOSFET Element 2M4, an inverter 20, a third P-type MOSFET element 2M5, and a third N-type MOSFET element 2M6.

。 In more detail, when calculating the input inversion point voltage V _{INV of} the CMOS Schmitt circuit 2, the first P-type MOSFET element 2M1 and the second P-type MOSFET element 2M2 can be the same P-type MOSFET element , And at the same time let the first N-type MOSFET element 2M3 and the second N-type MOSFET element 2M4 be the same N-type MOSFET element. In this way, ignoring the element parameters of the third P-type MOSFET element 2M5 and the third N-type MOSFET element 2M6, the mathematical expression _{of the input inversion point voltage V INV can be derived as follows:}

.

In the foregoing mathematical expressions, V _DD is the operating voltage provided by a low-voltage power supply circuit, V _TN and V _TP are the threshold voltages of N-type MOSFET and P-type MOSFET respectively, and γ=β _P /β _N , Where β _P is the gain factor of the P-type MOSFET element, which is μ _P C _OX (W _P /L _P ), and β _N is the gain factor of the N-type MOSFET element, which is μ _N C _OX (W _N /L _N ). Among them, μ _P is the hole mobility _{of the inversion layer, μ N} is the electron mobility of the inversion layer, Cox is the thickness of the gate oxide layer, W _P (W _N ) is the gate width, and L _P (L _nN ) is the gate length. Therefore, it can be known from the foregoing mathematical expression that the operating voltage V _DD provided by the low-voltage power supply circuit, the element size of the P-type MOSFET element and the N-type MOSFET element, and/or the threshold voltage of the P-type MOSFET element and the N-type MOSFET element Both will affect the final value of the input inversion point voltage V _INV.

The CMOS Schmitt circuit 2 shown in Figure 1 is often used as a digital input buffer, which uses the third P-type MOSFET element 2M5 and the third N-type MOSFET element 2M6 to make a logic high level (Logic-high ) There is a certain hysteresis between the output signal V _OUT and the logic-low output signal V _OUT to prevent repeated high/low level switching from causing glitches in the output signal VOUT near the input flip point . _{It is worth noting that the working voltage V DD} provided by the low-voltage power supply circuit is usually required to be between 2.5V and 5.5V. _{The range of this working voltage V DD} can allow the CMOS Schmitt circuit 2 shown in Figure 1 to be The maximum value of the output logic-low output signal V _OUT is 0.6V, and the minimum value of the output logic-high output signal V _{OUT is 2.0V.}

_{However, the working voltage V DD} in the range of 2.5V~5.5V provided by the low-voltage power supply circuit cannot make the maximum value of the logic _{-low output signal V OUT} be 0.6V and the logic high level (Logic-low). -high) The minimum value of the output signal V _{OUT is 1.5V.} In view of this, Figure 3 shows a conventional Schmitt circuit including a low dropout voltage regulator. As shown in FIG. 3, a low-dropout regulator (LDO) 3 is applied to provide a low-dropout operating voltage V _LDO to the CMOS Schmitt circuit 2, so that a logic low (Logic low) voltage V LDO is applied to the CMOS Schmitt circuit 2. -low) The maximum value of the output signal V _OUT is 0.6V, and at the same time, the minimum value of the _{logic-high output signal V OUT is 1.5V.}

Unfortunately, the Schmitt circuit including the low dropout regulator shown in Figure 3 cannot simultaneously satisfy the logic-low output signal V _OUT with a maximum value of 0.6V and a logic high level (Logic-low). high) The minimum value of the output signal V _OUT is the requirement of 1.2V, 1.1V or 1.05V. Therefore, further consideration should be given to how to select 5V electronic components to design a new low-voltage power supply circuit so that the (CMOS) Schmitt circuit containing this new low-voltage power supply circuit can simultaneously meet the logic-low output signal The maximum value of V _OUT is 0.6V and the minimum value of the logic-high output signal V _OUT is 1.2V, 1.1V or 1.05V.

Therefore, there is an urgent need in the art for a new type of power supply circuit used in digital input buffers.

The main purpose of the present invention is to provide a power supply circuit for adjusting a working voltage to a low-dropout working voltage, and providing the low-dropout working voltage to a Schmitt circuit unit, so that one of the Schmitt circuit units has a logic high The minimum value of the Logic-high output signal can reach 1.2V, 1.1V, or 1.05V, and at the same time, the maximum value of the logic-low output signal of one of the Schmitt circuit units can reach 0.6V.

Another object of the present invention is to provide a power supply circuit, which is used to adjust a working voltage to a low dropout working voltage. The adjustment process is compatible with compensating for the process angle changes of the N-type MOSFET element and the P-type MOSFET element, so that the worst case The N-type MOSFET element and P-type MOSFET element in the process corner are changed from the SNFP or FNSP process angle to the SS or FF process angle, thereby adjusting the input switching point voltage of the Schmitt circuit unit to make it within the range of the full process angle Changes can be effectively controlled without significant changes.

In order to achieve the above objective, the present invention proposes a first embodiment of the power supply circuit, which is used to provide a low dropout operating voltage to a Schmitt circuit unit, and it includes: a first MOSFET element with a drain terminal And a source terminal are respectively coupled to a working voltage and a ground terminal voltage; a current source is coupled between a gate terminal of the first MOSFET element and the working voltage; a second MOSFET element with a source terminal thereof Simultaneously coupled to the current source and the gate terminal of the first MOSFET element, and a drain terminal and a gate terminal thereof are coupled to each other; and a first resistor whose one end is simultaneously coupled to the second MOSFET element The drain terminal and the gate terminal, and the other terminal thereof is coupled to the ground terminal voltage; wherein, the source terminal of the first MOSFET element is an output terminal of the power supply circuit for providing the low dropout operating voltage to the application Mitter circuit unit.

In the first embodiment, the power supply circuit further includes: A second resistor, coupled between the first resistor and the ground terminal voltage; a third resistor, coupled between the source terminal of the first MOSFET element and the ground terminal voltage; a fourth resistor, Coupled between the drain terminal of the first MOSFET element and the operating voltage; and a capacitor, coupled between the gate terminal of the first MOSFET element and the ground terminal voltage; wherein, the current source includes a Resistance and a band gap reference voltage across the resistance.

In order to achieve the above objective, the present invention further provides a second embodiment of the power supply circuit, which is used to provide a low dropout operating voltage to a Schmitt circuit unit, and it includes: a first MOSFET element with one drain A terminal and a source terminal are respectively coupled to a working voltage and a ground terminal voltage; a current source is coupled between a gate terminal of the first MOSFET element and the working voltage; and a second MOSFET element with one of The source terminal is simultaneously coupled to the current source and the gate terminal of the first MOSFET element, a drain terminal thereof is coupled to the ground terminal voltage, and a gate terminal thereof is coupled to a clamp reference voltage; wherein, the first MOSFET The source terminal of the element is an output terminal of the power supply circuit for providing the low dropout operating voltage to the Schmitt circuit unit.

In the second embodiment, the power supply circuit further includes: a first resistor coupled between the drain terminal of the second MOSFET element and the ground terminal voltage; and a second resistor coupled to the first MOSFET Between the source terminal and the ground terminal voltage of the element; a third resistor coupled between the drain terminal of the first MOSFET element and the operating voltage; and a capacitor coupled to the first MOSFET element Between the gate terminal and the ground terminal voltage.

To achieve the above objective, the present invention further provides a third embodiment of the power supply circuit, which is used to provide a low dropout operating voltage to a Schmitt circuit unit, and it includes:

An operational amplifier having a positive input terminal, a negative input terminal and an output terminal coupled to a reference voltage;

A first MOSFET element, a source terminal of which is coupled to the output terminal of the operational amplifier, and a drain terminal and a gate terminal of which are coupled to each other;

A first resistor, one end of which is simultaneously coupled to the drain terminal and the gate terminal of the first MOSFET element, and the other end of which is coupled to the negative input terminal of the operational amplifier; and

A second resistor, coupled between the first resistor and a ground terminal voltage;

Wherein, a common contact between the source terminal of the first MOSFET element and the output terminal of the operational amplifier is an output terminal of the power supply circuit for providing the low dropout operating voltage to the Schmitt circuit unit .

In the third embodiment, the power supply circuit further includes a third resistor coupled between the second resistor and the ground terminal voltage.

To achieve the above objective, the present invention further provides a fourth embodiment of the power supply circuit, which is used to provide a low dropout operating voltage to a Schmitt circuit unit, and includes:

A stable voltage supply unit, including:

A first operational amplifier having a positive input terminal, a negative input terminal and an output terminal coupled to a reference voltage;

A first resistor coupled between the output terminal and the negative input terminal of the first operational amplifier; and

A second resistor, one end of which is coupled to a ground terminal, and the other end of which is simultaneously coupled to the first resistor and the output terminal of the first operational amplifier; and

A voltage-current conversion unit, coupled to a common contact between the negative input terminal of the first operational amplifier and the second resistor, a working voltage, and a ground terminal voltage, for providing a current to the Common contact

Wherein, the power supply circuit uses the output terminal of the first operational amplifier to provide the low dropout operating voltage to the Schmitt circuit unit.

In the third embodiment, the voltage-current conversion unit includes:

A second operational amplifier having a positive input terminal, a negative input terminal and an output terminal;

A first MOSFET element, a gate terminal and a drain terminal of which are respectively coupled to the output terminal and the negative input terminal of the second operational amplifier;

A third resistor, one end of which is coupled to a working voltage, and the other end of which is simultaneously coupled to the negative input terminal of the second operational amplifier and a source terminal of the first MOSFET element;

A current mirror coupled to the drain terminal of the first MOSFET element, a ground terminal voltage, and a common connection point between the negative input terminal of the first operational amplifier, the first resistor and the second resistor at the same time;

A second MOSFET element, a gate terminal of which is coupled to the positive input terminal of the second operational amplifier, a source terminal of which is coupled to the operating voltage, and a drain terminal of which is simultaneously coupled to the positive input of the second operational amplifier Terminal and the ground terminal voltage; and

A current source, one end of which is coupled to the ground terminal voltage, and the other end of which is simultaneously coupled to the drain terminal of the second MOSFET element and the positive input terminal of the second operational amplifier.

The present invention also provides a digital input buffer, which includes the power supply circuit as described above.

In a feasible embodiment, the digital input buffer is applied to a digital analog conversion circuit, a power-on reset circuit, an ultrasonic sensor circuit, a photoelectric sensor circuit, a capacitive fingerprint sensor circuit, an optical fingerprint sensor circuit, and electronics. An electronic circuit device in the group consisting of a switching circuit, a signal switching control circuit, an IGBT drive control circuit, a current threshold detection circuit, and a voltage threshold detection circuit.

To achieve the above objective, the present invention further provides a control chip, which has a control circuit and the aforementioned power supply circuit, wherein the control circuit is powered by the power supply circuit.

To achieve the above objective, the present invention further provides an information processing device, which has the aforementioned control chip.

In order to enable your reviewer to further understand the structure, features, purpose, and advantages of the present invention, the drawings and detailed descriptions of preferred specific embodiments are attached as follows.

FIG. 4 shows a circuit topology diagram of the first embodiment of a power supply circuit of the present invention. In the first embodiment, the power supply circuit 100 of the present invention is used to provide a low dropout operating voltage V _LDO to a Schmitt circuit unit 2, and it includes: a first MOSFET element 101, a current source 102, and a second Two MOSFET elements 103, a first resistor 104, a second resistor 105, a third resistor 106, a fourth resistor 107, and a capacitor 108. As shown in FIG. 4, the first MOSFET element 101 is an N-type MOSFET element, a drain terminal and a source terminal of which are respectively coupled to a working voltage V _DD and a ground terminal voltage V _SS . Moreover, the current source 102 is coupled between a gate terminal of the first MOSFET element 101 and the operating voltage V _DD . Specifically, the current source 102 includes a resistor and a band gap reference voltage V _BG across the resistor. Simply put, the output current value of the current source 102 is V _BG /R, where R is the resistance value of the aforementioned resistor.

On the other hand, the second MOSFET element 103 is a P-type MOSFET element. As shown in FIG. 4, a source terminal of the second MOSFET element 103 is simultaneously coupled to the current source 102 and the gate terminal of the first MOSFET element 101, and a drain terminal and a gate terminal thereof are coupled to each other. In more detail, one end of the first resistor 104 is simultaneously coupled to the drain terminal and the gate terminal of the second MOSFET element 103, and the other end is coupled to the ground terminal voltage V _SS . Moreover, the second resistor 105 is coupled between the first resistor 104 and the ground terminal voltage V _SS , and the third resistor 106 is coupled between the source terminal of the first MOSFET element 101 and the ground terminal voltage V _SS In between, the fourth resistor 107 is coupled between the drain terminal of the first MOSFET element 101 and the operating voltage V _DD , and the capacitor 108 is coupled between the gate terminal of the first MOSFET element 101 and the ground Between terminal voltage V _SS.

The source terminal of the first MOSFET element 101 (ie, the N-type MOSFET element) is an output terminal of the power supply circuit 100 for providing the low dropout operating voltage V _LDO to the Schmitt circuit unit 2. According to the design of the present invention, the value of the constant current output by the current source 102 is V _BG /R, and it can be seen from FIG. 4 that the constant current flows sequentially through the second MOSFET element 103 (that is, the P-type MOSFET element) , The first resistor 104 and the second resistor 105, so the low dropout operating voltage V _LDO =Ibxu*(R1+R2)+Vgsp-Vgsn can be calculated. In the foregoing calculation formula, Ibxu is the constant current output by the current source 102, R1 is the resistance value of the first resistor 104, R2 is the resistance value of the second resistor 105, Vgsp=V _TP +Vov, and Vgsn=V _TN + Vov. In more detail, V _TP and V _TN are the threshold voltages of the P-type MOSFET and N-type MOSFET, respectively, and Vov is the overdrive voltage of the MOSFET. Moreover, the aforementioned calculation formula can be further derived into the following mathematical calculation formula: VLDO=VBG*(R1+R2)/R+VTP-VTN…………(1).

An exemplary circuit topology of the Schmitt circuit unit 2 is shown in FIG. 1, and it is known that the input inversion point voltage V _{INV of the} Schmitt circuit unit 2 can be calculated by the following mathematical expression:

The power supply circuit 100 of the present invention provides the low dropout operating voltage V _LDO to the Schmitt circuit unit 2, so the above formula (1) can be substituted into the formula (2) to obtain the following mathematical expression:

In the aforementioned formula (3), γ=β _P /β _N. Also, β _P is the gain factor of the P-type MOSFET element, which is μ _P C _OX (W _P /L _P ). On the other hand, β _N is the gain factor of the N-type MOSFET element, which is μ _N C _OX (W _N /L _N ). It must be noted that when the working voltage V _DD remains unchanged, one of the worst cases of the process corner is SNFP, that is, the NMOS is slow and the PMOS is fast. The worst-case process angle determines whether the minimum value of the logic-high output signal V _OUT of the Schmitt circuit unit 2 can reach 1.2 V, 1.1 V, or 1.05 V. On the other hand, when the operating voltage V _{DD is} unchanged, another worst case of the process angle is FNSP, that is, NMOS is fast and PMOS is man. This worst-case process angle determines whether the maximum value of the logic-low output signal V _{OUT of the Schmitt circuit unit 2 can reach 0.6V.}

Therefore, it can be seen from the aforementioned formula (3) that the power supply circuit 100 of the present invention is used to _{adjust the operating voltage V DD} to a low dropout operating voltage V _LDO , and the adjustment process is compatible with compensating the N-type MOSFET element and the P-type MOSFET element. Process angle changes. With this design, even if the threshold voltage of the N-type MOSFET element and/or the P-type MOSFET element becomes the worst case process angle due to process errors, the power supply circuit 100 of the present invention can reduce or increase the low voltage Differential working voltage V _{LDO changes} the N-type MOSFET element and P-type MOSFET element of the worst-case process angle from the SNFP or FNSP process angle to the SS or FF process angle, thereby regulating the input of the Schmitt circuit unit 2 The inversion point voltage V _INV enables the change in the full process angle range to be effectively controlled without significant changes. For example, in the case of a worst case process angle SNFP, the power supply circuit 100 of the present invention can appropriately reduce the low dropout operating voltage V _LDO . Moreover, in the case of another worst-case process angle FNSP, the power supply circuit 100 of the present invention can appropriately increase the low dropout operating voltage V _LDO .

FIG. 5 shows a circuit topology diagram of a second embodiment of a power supply circuit of the present invention. In the second embodiment, the power supply circuit 200 of the present invention is used to provide a low dropout operating voltage V _LDO to a Schmitt circuit unit 2, and it includes: a first MOSFET element 201, a current source 202, and a second Two MOSFET elements 203, a first resistor 204, a second resistor 206, a third resistor 207, and a capacitor 208. As shown in FIG. 5, the first MOSFET element 201 is an N-type MOSFET element, and a drain terminal and a source terminal thereof are respectively coupled to a working voltage V _DD and a ground terminal voltage V _SS . Moreover, the current source 202 is coupled between a gate terminal of the first MOSFET element 201 and the operating voltage V _DD . On the other hand, the second MOSFET element 203 is a P-type MOSFET element, and a source terminal thereof is simultaneously coupled to the current source 202 and the gate terminal of the first MOSFET element 201. Moreover, a drain terminal and a gate terminal of the second MOSFET element 203 are respectively coupled to the ground terminal voltage V _SS and a clamp reference voltage V _{REF_CLAMP} .

In more detail, the first resistor 204 is coupled between the drain terminal of the second MOSFET element 203 and the ground terminal voltage V _SS , and the second resistor 206 is coupled to the source terminal of the first MOSFET element 201 And the ground terminal voltage VSS, the third resistor 207 is coupled between the drain terminal of the first MOSFET element 201 and the operating voltage V _DD , and the capacitor 208 is coupled to the first MOSFET element 201 Between the gate terminal and the ground terminal voltage V _SS.

In the second embodiment, the source terminal of the first MOSFET element 201 is an output terminal of the power supply circuit 200 for providing the low dropout operating voltage V _LDO to the Schmitt circuit unit 2. It can be known from the circuit topology of FIG. 5 that the low dropout operating voltage V _LDO =V _{REF_CLAMP} +V _gsp -V _gsn . Where V _{REF_CLAMP} is a clamp reference voltage used to control the on/off of the _{second MOSFET element 203, V gsp} is the gate-source voltage difference of the second MOSFET element 203, and V _gsn is the voltage of the first MOSFET element 201 Gate-source voltage difference. Moreover, the aforementioned calculation formula can be further derived into the following mathematical calculation formula: V _LDO =V _{REF_CLAMP} +V _TP -V _TN …………(4).

The power supply circuit 200 of the present invention provides the low dropout operating voltage V _LDO to the Schmitt circuit unit 2. Therefore, the above equation (4) can be substituted into the equation (2) described above to obtain the following mathematical expression:

It can be seen from the aforementioned formula (5) that the power supply circuit 200 of the present invention is used to _{adjust the operating voltage V DD} to a low dropout operating voltage V _LDO , and the adjustment process is compatible with compensating the process angle of the N-type MOSFET element and the P-type MOSFET element. Variety. For example, in the case of a worst case process angle SNFP, the power supply circuit 100 of the present invention can appropriately reduce the low dropout operating voltage V _LDO . Moreover, in the case of another worst-case process angle FNSP, the power supply circuit 100 of the present invention can appropriately increase the low dropout operating voltage V _LDO . With this design, the worst-case N-type MOSFET element and P-type MOSFET element are changed from the SNFP or FNSP process angle to the SS or FF process angle, and the input inversion point voltage V _{INV of} the Schmidt circuit unit 2 can be adjusted. The changes in the full process angle range can be effectively controlled without significant changes.

FIG. 6 shows a circuit topology diagram of a third embodiment of a power supply circuit of the present invention. In the third embodiment, the power supply circuit 300 of the present invention is used to provide a low dropout operating voltage V _LDO to a Schmitt circuit unit 2, and it includes: an operational amplifier 301, a first MOSFET element 302, and a second A resistor 303, a second resistor 304, and a third resistor 305. The operational amplifier 301 has a positive input terminal, a negative input terminal and an output terminal coupled to a reference voltage V _REF. The first MOSFET element 302 is a P-type MOSFET element, and a source terminal thereof is coupled to the output terminal of the operational amplifier 301, and a drain terminal and a gate terminal thereof are coupled to each other. On the other hand, one terminal of the first resistor 303 is simultaneously coupled to the drain terminal and the gate terminal of the first MOSFET element 302, and the other terminal is coupled to the negative input terminal of the operational amplifier 301. 6 also shows that the second resistor 304 is coupled between the first resistor 303 and a ground terminal voltage V _SS , and the third resistor 305 is coupled between the second resistor 304 and the ground terminal voltage V _SS between.

In the third embodiment, a common contact between the source terminal of the first MOSFET element 302 and the output terminal of the operational amplifier 301 is an output terminal of the power supply circuit 300 to provide the low dropout voltage The working voltage V _{LDO is connected} to the Schmitt circuit unit 2. It can be seen from the circuit topology of FIG. 6 that the first MOSFET element 302 is connected in series to the feedback loop of the operational amplifier 301 in the present invention. Since the first MOSFET element 302 is a diode-connected P-type MOSFET element, the low dropout operating voltage V _LDO will vary with the process angle of the P-type MOSFET element. The low dropout operating voltage V _LDO is: V _REF *(R3+R2+R1)/(R1+R2)+V _gsp . Among them, R3 is the resistance value of the first resistor 303, R2 is the resistance value of the second resistor 304, R1 is the resistance value of the third resistor 301, and V _gsp =V _TP +Vov. V _TP is the threshold voltage of the P-type MOSFET element, and Vov is the overdrive voltage of the MOSFET element. Moreover, the aforementioned calculation formula can be further derived into the following mathematical calculation formula: V _LDO =V _REF *(R3+R2+R1)/(R1+R2)+V _TP +Vov……(6).

…………………………(7)。 The power supply circuit 300 of the present invention provides the low dropout operating voltage V _LDO to the Schmitt circuit unit 2. Therefore, the above formula (5) can be substituted into the formula (2) described above to obtain the following mathematical expression:

…………………………(7).

It can be seen from the aforementioned formula (7) that the power supply circuit 300 of the present invention is used to _{adjust the operating voltage V DD} to a low dropout operating voltage V _LDO , and the adjustment process is compatible with compensating the process angle of the N-type MOSFET element and the P-type MOSFET element. The specific effect is to change the N-type MOSFET element and P-type MOSFET element of the worst-case process angle from the SNFP or FNSP process angle to the SS or FF process angle, so as to adjust the input switching point voltage of the Schmitt circuit unit 2. V _INV , so that the change in the full process angle range can be effectively controlled without significant changes.

FIG. 7 shows a circuit topology diagram of a fourth embodiment of a power supply circuit of the present invention. In the fourth embodiment, the power supply circuit 400 of the present invention is used to provide a low dropout operating voltage V _LDO to a Schmitt circuit unit 2, and it is mainly composed of a stable voltage supply unit 410 and a voltage-current conversion unit 420. As shown in FIG. 7, the stable voltage supply unit 410 includes: a first operational amplifier 411, a first resistor 412 and a second resistor 413. The first operational amplifier 411 has _{a positive input terminal, a negative input terminal, and an output terminal coupled to a reference voltage V REF} , and the first resistor 412 is coupled to the output terminal of the first operational amplifier 411 And the negative input terminal. Moreover, one end of the second resistor 413 is coupled to a ground end, and the other end thereof is simultaneously coupled to the first resistor 412 and the output end of the first operational amplifier 411. According to the design of the present invention, the voltage-current conversion unit 420 is coupled to a common connection point between the negative input terminal of the first operational amplifier 411 and the second resistor 413, a working voltage V _DD , and a ground terminal voltage Between V and _SS , it is used to provide a current to the common contact. In addition, the power supply circuit 100 uses the output terminal of the first operational amplifier 411 to provide the low dropout operating voltage V _LDO to the Schmitt circuit unit 2.

In more detail, the voltage-current conversion unit 420 includes: a second operational amplifier 421, a first MOSFET element 422, a third resistor 423, a second MOSFET element 424, a current source 425, and a current mirror ( Including a third MOSFET element 426 and a fourth MOSFET element 427). Wherein, the second operational amplifier 421 has a positive input terminal, a negative input terminal and an output terminal, and the first MOSFET element 422 is respectively coupled to the second operational amplifier 421 with a gate terminal and a drain terminal thereof. The output terminal and the negative input terminal. On the other hand, one end of the third resistor 423 is coupled to a working voltage V _DD , and the other end thereof is simultaneously coupled to the negative input terminal of the second operational amplifier 421 and a source terminal of the first MOSFET element 422. As shown in FIG. 7, a gate terminal of the second MOSFET element 424 is coupled to the positive input terminal of the second operational amplifier 421, a source terminal is coupled to the operating voltage V _DD , and a drain terminal thereof is simultaneously coupled Connect the positive input terminal of the second operational amplifier 421 and the ground terminal voltage V _SS .

Following the above description, one terminal of the current source 425 is coupled to the ground terminal voltage V _SS , and the other terminal thereof is simultaneously coupled to the drain terminal of the second MOSFET element 424 and the positive input terminal of the second operational amplifier 421. FIG. 7 also shows that the current mirror is an NMOS current mirror, which is composed of the third MOSFET element 426 and the fourth MOSFET element 427. The source terminal and the drain terminal of the third MOSFET element 426 are respectively coupled to the ground terminal voltage V _SS and the drain terminal of the first MOSFET element 422, and the gate terminal is coupled to the drain terminal. In addition, the source terminal and the drain terminal of the fourth MOSFET element 427 are respectively coupled to the ground terminal voltage V _SS and the negative input terminal of the first operational amplifier 411, the common value between the first resistor 412 and the second resistor 413. The gate terminal is coupled to the gate terminal of the first MOSFET element 422.

In the fourth embodiment, the voltage-current conversion unit 420 converts the Vgsp voltage of the second MOSFET element 424 into a current, and the current is Vgsp/R0; where Vgsp=V _TP +Vov, and R0 is the third resistor 423 resistance value. The current is transmitted to the common connection point between the negative input terminal of the first operational amplifier 411 and the first resistor 412 and the second resistor 413 through the fourth MOSFET element 427 of the current mirror, so that all The low dropout operating voltage V _LDO =V _REF *(R2+R1)/R1+V _gsp *R2/R0. It can be seen that adjusting the ratio of R2/R0 can change the final value of the _{low dropout operating voltage V LDO.} In the case that R2/R0=1, the aforementioned calculation formula can be further derived into the following mathematical calculation formula: V _REF *(R2+R1)/R1+V _gsp ……(8).

…………………………(9)。 The power supply circuit 400 of the present invention provides the low dropout operating voltage V _LDO to the Schmitt circuit unit 2. Therefore, the above equation (8) can be substituted into the equation (2) described in the previous description to obtain the following mathematical expression:

…………………………(9).

It can be seen from the aforementioned formula (9) that the power supply circuit 400 of the present invention is used to _{adjust the operating voltage V DD} to a low dropout operating voltage V _LDO , and the adjustment process is compatible with compensating the process angle of the N-type MOSFET element and the P-type MOSFET element. The specific effect is to change the N-type MOSFET element and P-type MOSFET element of the worst-case process angle from the SNFP or FNSP process angle to the SS or FF process angle, so as to adjust the input switching point voltage of the Schmitt circuit unit 2. V _INV , so that the change in the full process angle range can be effectively controlled without significant changes.

According to the above description, the present invention can further provide a digital input buffer, which includes a Schmitt circuit unit 2 and any embodiment of the power supply circuit (100, 200, 300, 400) of the present invention as described above. In a feasible embodiment, the digital input buffer is applied in an electronic circuit device, and the electronic circuit device can be any of the following: digital-to-analog conversion circuit, power-on reset circuit, ultrasonic sensor circuit, photoelectric sensor Circuit, capacitive fingerprint sensor circuit, optical fingerprint sensor circuit, electronic switch circuit, signal switching control circuit, IGBT drive control circuit, current threshold detection circuit, and voltage threshold detection circuit.

Based on the above description, the present invention can further provide a control chip having the aforementioned power supply circuit and a control circuit, wherein the control circuit is powered by the power supply circuit to provide stable and reliable working performance.

Based on the above description, the present invention can further provide an information processing device with the aforementioned control chip to provide stable and reliable working performance.

In this way, the above has completely and clearly described a power supply circuit of the present invention; and from the above, it can be seen that the present invention has the following advantages:

(1) The power supply circuit of the present invention can adjust a working voltage V _DD into a low-dropout working voltage V _LDO , and provide the low-dropout working voltage V _LDO to a Schmitt circuit unit 2 so that the Schmitt circuit unit 2 The minimum value of a logic-high output signal can reach 1.2V, 1.1V, or 1.05V, and at the same time, a logic-low output signal of the Schmitt circuit unit 2 The maximum value can reach 0.6 V.

(2) The present invention provides four exemplary embodiments of the power supply circuit, all of which can be used to _{adjust an operating voltage V DD} to a low dropout operating voltage V _LDO , and the adjustment process is compatible with compensating N-type MOSFET components and P-type MOSFETs. The process angle of the device changes, so that the N-type MOSFET element and P-type MOSFET element of the worst-case process angle are changed from the SNFP or FNSP process angle to the SS or FF process angle, thereby adjusting the input flip point of the Schmitt circuit unit 2 The voltage V _INV can be effectively controlled without any obvious change in the whole process angle range.

It must be emphasized that the foregoing disclosures in this case are preferred embodiments, and any partial changes or modifications that are derived from the technical ideas of this case and are easily inferred by those who are familiar with the art will not deviate from the patent of this case. Right category.

In summary, regardless of the purpose, means, and effects of this case, it is shown that it is very different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. Please check it out and grant the patent as soon as possible. Society is for the best prayer.

<The present invention>

2: Schmidt circuit unit

100: power supply circuit

101: The first MOSFET element

102: current source

103: The second MOSFET element

104: first resistance

105: second resistor

106: third resistor

107: Fourth resistor

108: Capacitor

200: power supply circuit

201: The first MOSFET element

202: current source

203: The second MOSFET element

204: first resistance

206: second resistor

207: third resistor

208: Capacitor

300: power supply circuit

301: Operational amplifier

302: The first MOSFET element

303: first resistance

304: second resistor

305: third resistor

400: power supply circuit

410: Stable voltage supply unit

411: The first operational amplifier

412: first resistance

413: second resistor

420: voltage-current conversion unit

421: second operational amplifier

422: The first MOSFET element

423: third resistor

424: second MOSFET element

425: current source

426: third MOSFET element

427: Fourth MOSFET element

＜Acquaintances＞

2: CMOS Schmitt circuit

20

2M1: The first P-type MOSFET element

2M2: Second P-type MOSFET element

2M3: The first N-type MOSFET element

2M4: Second N-type MOSFET element

2M5: The third P-type MOSFET element

2M6: The third N-type MOSFET element

3: Low dropout regulator

Figure 1 is a circuit topology diagram of a conventional CMOS Schmitt circuit; Figure 2 is the equivalent circuit symbol of the conventional CMOS Schmitt circuit; Figure 3 is a conventional Schmitt circuit including a low dropout regulator; 4 is a circuit topology diagram of the first embodiment of a power supply circuit of the present invention; Fig. 5 is a circuit topology diagram of a second embodiment of a power supply circuit of the present invention; Fig. 6 is a circuit topology diagram of a third embodiment of a power supply circuit of the present invention; and FIG. 7 is a circuit topology diagram of a fourth embodiment of a power supply circuit of the present invention.

2: Schmidt circuit unit

100: power supply circuit

101: The first MOSFET element

102: current source

103: The second MOSFET element

104: first resistance

105: second resistor

106: third resistor

107: Fourth resistor

108: Capacitor

Claims (9)

A power supply circuit for providing a low dropout operating voltage to a Schmitt circuit unit, and comprising: a first MOSFET element, a drain terminal and a source terminal of which are respectively coupled to a working voltage and a ground terminal voltage ; A current source, coupled between a gate terminal of the first MOSFET element and the operating voltage; a second MOSFET element, a source terminal of which is simultaneously coupled to the current source and the gate of the first MOSFET element Terminal, and a drain terminal and a gate terminal are coupled to each other; and a first resistor, one end of which is simultaneously coupled to the drain terminal and the gate terminal of the second MOSFET element, and the other end is coupled to the ground Terminal voltage; wherein, the source terminal of the first MOSFET element is an output terminal of the power supply circuit for providing the low dropout operating voltage to the Schmitt circuit unit. The power supply circuit described in item 1 of the scope of patent application further includes: a second resistor, coupled between the first resistor and the ground terminal voltage; a third resistor, coupled to the first MOSFET element Between the source terminal and the ground terminal voltage; a fourth resistor, coupled between the drain terminal of the first MOSFET element and the operating voltage; and a capacitor, coupled to the gate of the first MOSFET element Between the terminal and the ground terminal voltage; wherein, the current source includes a resistor and a band gap reference voltage across the resistor. A power supply circuit for providing a low dropout operating voltage to a Schmitt circuit unit, and comprising: a first MOSFET element, a drain terminal and a source terminal of which are respectively coupled to a working voltage and a ground terminal voltage ; A current source, coupled between a gate terminal of the first MOSFET element and the operating voltage; and A second MOSFET element, with a source terminal thereof simultaneously coupled to the current source and the gate terminal of the first MOSFET element, a drain terminal thereof coupled to the ground terminal voltage, and a gate terminal thereof coupled to a clamp Reference voltage; wherein, the source terminal of the first MOSFET element is an output terminal of the power supply circuit for providing the low dropout operating voltage to the Schmitt circuit unit. The power supply circuit described in item 3 of the scope of patent application further includes: a first resistor coupled between the drain terminal of the second MOSFET element and the ground terminal voltage; and a second resistor coupled to the first resistor Between the source terminal of a MOSFET element and the ground terminal voltage; a third resistor coupled between the drain terminal of the first MOSFET element and the operating voltage; and a capacitor coupled to the first MOSFET Between the gate terminal and the ground terminal voltage of the component. A power supply circuit is used to provide a low dropout operating voltage to a digital input buffer, and includes: a stable voltage supply unit, including: a first operational amplifier having a positive input terminal coupled to a reference voltage, a A negative input terminal and an output terminal; a first resistor coupled between the output terminal and the negative input terminal of the first operational amplifier; and a second resistor, one end of which is coupled to a ground terminal, and The other end is simultaneously coupled to the first resistor and the output end of the first operational amplifier; and a voltage-to-current conversion unit, coupled to a common connection between the negative input end of the first operational amplifier and the second resistor Point, a working voltage, and a ground terminal voltage to provide a current to the common contact; wherein, the power supply circuit provides the low dropout working voltage to the output terminal of the first operational amplifier The Schmitt circuit unit; wherein, the voltage-current conversion unit includes: a second operational amplifier having a positive input terminal, a negative input terminal and an output terminal; A first MOSFET element with a gate terminal and a drain terminal respectively coupled to the output terminal and the negative input terminal of the second operational amplifier; a third resistor, one end of which is coupled to a working voltage, and the other end of the third resistor Simultaneously coupled to the negative input terminal of the second operational amplifier and a source terminal of the first MOSFET element; a current mirror, simultaneously coupled to the drain terminal of the first MOSFET element, a ground terminal voltage, and the first A common connection point between the negative input terminal of the operational amplifier, the first resistor and the second resistor; a second MOSFET element, one gate terminal of which is coupled to the positive input terminal of the second operational amplifier, and one source One terminal is coupled to the working voltage, and one of its drain terminals is simultaneously coupled to the positive input terminal of the second operational amplifier and the ground terminal voltage; and a current source, one terminal of which is coupled to the ground terminal voltage, and the other terminal of which is simultaneously The drain terminal of the second MOSFET element and the positive input terminal of the second operational amplifier are coupled. A digital input buffer includes the power supply circuit as described in any one of items 1 to 5 in the scope of the patent application. The digital input buffer as described in item 6 of the scope of patent application is used in selected from digital analog conversion circuits, power-on reset circuits, ultrasonic sensor circuits, photoelectric sensor circuits, capacitive fingerprint sensor circuits, and optical fingerprint sensors An electronic circuit device in the group consisting of a circuit, an electronic switch circuit, a signal switching control circuit, an IGBT drive control circuit, a current threshold detection circuit, and a voltage threshold detection circuit. A control chip is provided with a control circuit and the power supply circuit according to any one of items 1 to 5 in the scope of patent application, wherein the control circuit is powered by the power supply circuit. An information processing device having a control chip as described in item 8 of the scope of patent application.

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