JPH11274907A - Level shift circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of the level shift circuit by manufacturing the level shift circuit without employing a high breakdown strength PNP transistor(TR), a P-channel MOS TR, or a high breakdown strength NPN transistor(TR), an N-channel MOS TR. SOLUTION: An input signal Vin, having the same maximum amplitude as a voltage Va of a 1st power supply 4 is given to an input terminal 2. A series circuit consisting of 1st and 2nd resistors 9, 10 is connected between the input terminal 2 and a 2nd power supply 8 of level shift voltage-Vs. A series circuit consisting of 3rd and 4th resistors 11, 12 is connected between the 1st and 2nd power supplies 4, 8. The same resistance value R1 is selected for the 1st and 3rd resistors 9, 11 respectively. The same resistance R2 is selected for the 2nd and 4th resistors 10, 12 respectively. One input terminal (a) of a comparator 13 is connected to a voltage division position of the 1st and 2nd resistors 9, 10. The other input terminal (b) is connected to a voltage division position of the 3rd and 4th resistors 11, 12. A constant current source circuit 14 is connected in parallel with the 4th resistor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a level shift circuit suitable for a control circuit of an inverter circuit and the like.

[0002]

2. Description of the Related Art When controlling a pair of switches of a half-bridge type inverter circuit, it is necessary to change the voltage levels of one switch and the other switch. For this purpose, it is necessary to convert an input signal Vin of amplitude Va to a different level output signal Vout having the same amplitude Va as shown in FIG.

[0003]

A conventional level shift circuit is constructed using a PNP transistor or a P-channel MOS field effect transistor. But P
NP-type transistors and P-channel MOS field-effect transistors are more difficult to manufacture than NPN-type transistors and N-channel MOS field-effect transistors, have lower manufacturing yields, and inevitably increase their manufacturing costs.

Accordingly, an object of the present invention is to provide a high voltage PNP.
A level shift circuit is manufactured without using a transistor, a P-channel MOS transistor, or a high breakdown voltage NPN transistor or an N-channel MOS transistor to reduce the cost.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the above object, the present invention provides a first electric potential V1 and a second electric potential V1.
Circuit for shifting an input signal between the third potential V3 lower than the first potential V1 and a fourth potential V4 lower than the second potential V2. An input terminal for providing the input signal;
A first power supply terminal for applying a potential V2 of the
A second power supply terminal for applying the potential V3 of the first resistor, a first resistor having one end connected to the input terminal, and a second power supply terminal connected between the other end of the first resistor and the second power supply terminal. A second resistor, a third resistor having one end connected to the first power terminal, and a third resistor connected between the other end of the third resistor and the second power terminal. 4 and the first and second resistors
, An input terminal, an output terminal, and first and second comparator power supply terminals, wherein the first input terminal is connected to an interconnection point of the first and second resistors, and the second input terminal Is connected to the interconnection point of the third and fourth resistors, the first comparator power supply terminal is connected to the first power supply terminal, and the second comparator power supply terminal is connected to the second
A comparator connected to the power supply terminal of
A constant current source circuit connected between the other end of the first resistor and the second power supply terminal, wherein the resistance value of the first resistor is substantially the same as the resistance value of the third resistor. And the resistance of the second resistor is set to be substantially the same as the resistance of the fourth resistor, and the potential of the second input terminal of the comparator is changed to the first input signal. A first input potential obtained at the first input terminal of the comparator when the potential is equal to a second input potential, and a second input potential obtained at the first input terminal of the comparator when the input signal is at the second potential. And the current value of the constant current source circuit is set so as to obtain a level-shifted output of the input signal between the output terminal of the comparator and the second power supply terminal. Related to the level shift circuit, That. According to another aspect of the present invention, an input signal between a first potential V1 and a second potential V2 is supplied to a third potential V3 higher than the first potential V1 and the second potential V3. And a fourth power supply terminal for supplying the input signal, and a first power supply terminal for supplying the first potential V1. A second power supply terminal for applying the third potential V3; a first resistor having one end connected to the input terminal; another end of the first resistor; and a second power supply terminal , A third resistor having one end connected to the first power supply terminal, and a second resistor connected between the other end of the third resistor and the second power supply terminal. , A first resistor, a second input terminal, an output terminal, and first and second comparator power supply terminals. The first input terminal is connected to an interconnection point of the first and second resistors, and the second input terminal is connected to the third and fourth resistors.
The first comparator power supply terminal is connected to the second power supply terminal; and the third and fourth resistor interconnection points are connected to the second comparator. A constant current source circuit connected between the power supply terminal and the power supply terminal;
And the resistance value of the second resistor is set substantially equal to the resistance value of the fourth resistor, and the second input terminal of the comparator When the input signal is the first potential, the first input potential obtained at the first input terminal of the comparator when the input signal is the first potential and the first input potential of the comparator when the input signal is the second potential. A current value of the constant current source circuit is set so as to be between a second input potential obtained at an input terminal, and the input signal is supplied between an output terminal of the comparator and the second comparator power supply terminal. The present invention relates to a level shift circuit which is configured to obtain a level-shifted output.

[0006]

According to the present invention, the level shift can be performed by a simple and low-cost circuit including a resistor, a comparator, and a constant current source circuit.

[0007]

Embodiments and Examples Next, embodiments and examples of the present invention will be described with reference to the drawings.

[0008]

First Embodiment A level shift circuit 1 according to a first embodiment shown in FIG. 2 is a circuit for lowering the level of an input signal Vin as shown in FIG. 1, and has an input terminal 2 for supplying an input signal. Having. CP between the input terminal 2 and the ground
A signal generator 3 such as U is connected. Signal generator 3
Is the input signal V shown in FIG. 1 using the first power supply 4 as a power supply.
Generates in. This input signal Vin is a signal between the first potential V1 and the second potential V2, and is a signal for controlling on / off of the transistor. In this embodiment, the first potential V1 is 0 volt, that is, the ground potential, and the second potential V1 is
2 is a voltage Va of the first power supply 4.

The first power supply terminal 5 of the level shift circuit 1 is connected to the first power supply 4, and the second power supply terminal 7 is connected to the second power supply 8. The first power supply 4 has the same first voltage Va as the second potential V2 which is the maximum potential of the input signal Vin.
(Approximately 10 V), and the second power supply 8 supplies a negative voltage −Vs (for example, equal to the third potential V3, which is significantly lower than the first potential (0 V), which is the lowest potential of the input signal Vin). -400 V).

The level shift circuit 1 includes first, second, third, and fourth resistors 9, 10, 11, and 12, and a comparator 1
3 and a constant current source circuit 14. One end of the first resistor 9 is connected to the input terminal 2. The second resistor 10 is connected between the other end of the first resistor 9 and the second power supply terminal 7. One end of the third resistor 11 is connected to the first power supply terminal 5. The fourth resistor 12 is the third resistor 1
1 and the second power supply terminal 7.
The first and third resistors 9 and 11 have the same resistance value R1.
And the second and fourth resistors 10 and 12 have the same resistance value R2.

The comparator 13 has first and second input terminals a and b, an output terminal c, and first and second comparator power supply terminals d and e. The first input terminal a of the comparator 13, that is, the positive input terminal, is connected to the first and second resistors 9, 1.
0, the second input terminal b, ie, the negative input terminal, is connected to the interconnection point P2 of the third and fourth resistors 11, 12, and the output terminal c is connected to the first input terminal of the level shift circuit 1. 1, the first comparator power supply terminal d is connected to the first power supply terminal 5, the second comparator power supply terminal e is connected to the second power supply terminal 7, and the second comparator power supply terminal e is connected to the second power supply terminal 7. It is connected to the output terminal 16.

The constant current source circuit 14 includes the third and fourth resistors 1
The interconnection point P2 of the comparators 13 and 12,
Between the input terminal b and the second power supply terminal 7 to supply a constant current Ib. Note that the current Ib is equal to the third resistance 1
Flow to 1.

The level shift circuit 1 controls a first FET 17 of an inverter circuit having first and second FETs 17 and 18 as switching elements. The first output terminal 15 is connected to a first output terminal 15. , And the second output terminal 16 is connected to the source. As shown in FIG. 1, the output signal Vout between the first and second output terminals 15 and 16 is a negative potential as a third potential V3.
This signal changes in the range from Vs to -Vs + Va as the fourth potential V4. Therefore, the maximum value of the voltage between the gate and the source of the first FET 17 is Va, and -Vs
It operates normally despite the (-400V) level shift.

[0014]

[Operation] Next, the input signal Vin changes to the first potential V1 (0 V).
In this case, the voltage between both ends of the second resistor 10 (hereinafter referred to as the off input voltage) is Vg0, and the input signal Vin is the second potential V2.
The voltage between both ends of the second resistor 10 at (Va) (hereinafter, referred to as “Va”)
The on-input voltage) is Vga, the voltage between both ends of the fourth resistor 12 (hereinafter referred to as reference voltage) is Vr, and the fourth resistor 1 is
The operation of the level shift circuit 1 will be described with the current 2 as Ia.

The reference voltage Vr is determined by the first power supply 4, the third and fourth resistors 11, 12, the second power supply 8, and the constant current source circuit 1.
4 and can be expressed by the following equation (1). Vr = Va + Vs-R1 (Ia + Ib) (1) The reference voltage Vr can also be expressed by the following equation (2). Vr = R2Ia (2) Ia = Vr / R2 obtained from the equation (2) is expressed by (1)
Substituting into the equation gives the following equation (3). Vr = Va + Vs-R1 {(Vr / R2) + Ib} (3) By rearranging the equation (3), the following equation (4) is obtained. Vr = {R2 / (R1 + R2)} (Va + Vs-R1Ib) (4) On the other hand, the ON input voltage Vga can be expressed by the following equation (5). Vga = {R2 / (R1 + R2)} (Va + Vs) (5) Further, the off input voltage Vg0 can be expressed by the following equation (6). Vg0 = {R2 / (R1 + R2)} Vs (6) In this embodiment, the reference voltage Vr is set to an intermediate value between the off input voltage (first input voltage) Vg0 and the on input voltage (second input voltage) Vga. I do. Therefore, the reference voltage Vr can be expressed by the following equation (7). Vr = (Vga + Vg0) / 2 (7) By substituting equations (5) and (6) into equation (7), the following equation (8) is obtained.
Expression. Vr = [{R2 / (R1 + R2)} (Va + Vs) + {R2 / (R1 + R2)} Vs] / 2 = [R2 // 2 (R1 + R2)}] (Va + 2Vs) (8) (4) By substituting equation (8) into the equation, the following equation (9) is obtained. {R2 / (R1 + R2)} (Va + Vs-R1Ib) = [R2 / {2 (R1 + R2)}] (Va + 2Vs) (9) When the equation (9) is rearranged, the following equation (10) is obtained. Ib R1 = Va / 2 (10) From this equation (10), the constant current Ib becomes the following equation (11). Ib = Va / (2R1) (11)

Accordingly, the constant current Ib of the constant current source circuit 14 is set so as to satisfy the equation (11). Constant current I
If b is set so as to satisfy the expression (11), the reference voltage Vr supplied to the second input terminal b of the comparator 13 becomes equal to the off input voltage Vg0 supplied to the first input terminal a. It becomes an intermediate value with the ON reference voltage Vga, the comparator 13 responds to the input signal Vin, and the output signal Vout corresponding to the first potential V1 and the second potential V2 of the input signal Vin.
Occurs. The output signal Vout is -Vs = -400 as the third potential V3 when the input signal Vin is at the first potential V1.
V, and when the input signal Vin is at the second potential V2 = Va, the fourth potential V4 is V4 = -Vs + Va. Therefore, the output signal Vout becomes the input signal Vin as shown in FIG.
Is reduced by Vs.

Although -Vs is set to -400 V in the embodiment, setting Ib to the value of the equation (11) makes the operation of the comparator 13 independent of the value of the voltage -Vs of the second power supply 8. -Vs can be arbitrarily set, and the level shift amount can be arbitrarily set.

As an example, Va is 12 V, R1 is 4 MΩ,
-Vs when R2 is 40 kΩ and Ib = 1.5 μA
, Vr, Vga, and Vg0 are as follows. -Vs Vr Vga Vg0 0V 0.06V 0.12V 0.00V -100V 1.05V 0.11V 0.99V -200V 2.10V 2.22V 1.98V -40V 4.20V 4.44V 3.96V This table As is clear from FIG.
Regardless of the value of V to -400 V, the reference voltage Vr
That is, the threshold value of the comparator 13 is between Vga and Vg0, and the comparator 13 is operable.

As is apparent from the above description, the level shift circuit 1 of the present embodiment has a simple configuration including the resistors 9, 10, 11, and 12, the comparator 13, and the constant current source circuit 14, so that the cost can be reduced. become.

[0020]

Second Embodiment Next, a level shift circuit 1a according to a second embodiment will be described with reference to FIG. However, in FIG. 3, substantially the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. The level shift circuit 1a of FIG.
Are the first, second, third and fourth resistors 9 as in FIG.
10, 11, 12, a comparator 13, and a constant current source circuit 14. One end of the first resistor 9 is connected to the input terminal 2. The second resistor 10 is connected between the other end of the first resistor 9 and a second power supply terminal 7a for supplying the positive voltage + Vs. One end of the third resistor 11 is connected to the first power supply terminal 5a at the ground potential. The fourth resistor 12 is connected to the other end of the third resistor 11 and the second power supply terminal 7a.
Is connected between. As shown in FIG. 2, the comparator 13 has first and second input terminals a and b, an output terminal c,
It has first and second comparator power supply terminals d and e. The first and second input terminals a and b are connected to the first and second voltage dividing points P1 and P2 as in FIG. The output terminal c of the comparator 13 is connected to the first output terminal 15 of the level shift circuit 1a. The first comparator power terminal d is connected to the second power terminal 7a, and the second comparator power terminal e is connected to the second output terminal 16. The constant current source circuit 14 has a second voltage dividing point P2 and a second voltage dividing point P2.
And a comparator power supply terminal e. The signal generator 3 is connected between the input terminal 2 and the first power supply terminal 5a, that is, the ground, is driven by the first power supply 4a, and has a first potential V1 (0 V) as in FIGS. An input signal Vin is generated between the second potential V2 (Va). The second power supply 8a is connected between the second power supply terminal 7a and the ground, and has a positive voltage + Vs (for example, + 400V).
Occurs.

According to the second embodiment, the input signal Vin that changes between 0 and Va rises to the output signal Vout that changes between + Vs and + Vs + Va. Less than,
This will be described in detail.

Also in the second embodiment, the resistance values of the first and third resistors 9 and 11 are set to R1, and the resistance values of the second and fourth resistors 10 and 12 are set to R2.
Now, let the current flowing through the fourth resistor 12 be Ia, and the third resistor 1
1 is Ir, and the current of the constant current source circuit 14 is Ib.
When the input signal Vin is at the first potential V1 = 0, the voltage between the ground and the first voltage dividing point P1 (first input voltage) is Vg1, and the input signal Vin is at the second potential V2 = Va. Assuming that the voltage (second input voltage) between the ground and the first voltage dividing point P1 at this time is Vg2, Vg1 and Vg2 can be expressed by the following equations. Vg1 = R1 Vs / (R1 + R2) (12) Vg2 = R1 (Vs-Va) / (R1 + R2) (13) Further, the voltage between the ground and the second voltage dividing point P2, that is, the reference voltage Vr is defined as When set at an intermediate value between the first and second input voltages Vg1 and Vg2, the reference voltage Vr becomes a value represented by the following equation. Vr = (Vg1 + Vg2) / 2 (14) The current Ir can be expressed by the following two equations. Ir = Vr / R1 (15) Ir = Ia-Ib = {(Vs-Vr) / R2} -Ib (16) The following equation is established by the equations (15) and (16). Vr / R1 = {(Vs-Vr) / R2} -Ib (17) When this is arranged into the expression of Ib, the following expression is obtained. Ib = {(Vs-Vr) / R2} -Vr / R1 (18) By substituting Vr of equation (14) into equation (18),
Substituting equations (12) and (13) for g1 and Vg2, the following equation is established. Ib = Va / 2R2 (19) As is apparent from the equation (19), Ib becomes independent of the level shift voltage Vs. In short, the constant current source circuit 14
Is set so as to satisfy the equation (19), the input signal of the comparator 13 which changes between the first and second input voltages Vg1 and Vg2 is changed to an intermediate reference voltage (threshold). Value) Vr, and an output voltage Vout corresponding to the input signal Vin can be obtained. Therefore, the second
This embodiment has the same effect as the first embodiment.

[0023]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The output of the comparator 13 can be used for other than the inverter circuit. (2) Various circuits can be used as the signal generator 3. (3) The constant current source circuit 14 is the third resistor 11 shown in FIG.
In addition, any circuit may be used as long as a constant current can flow through the fourth resistor 12 in FIG.

[Brief description of the drawings]

FIG. 1 is a waveform diagram showing an input signal and an output signal obtained by leveling down the input signal.

FIG. 2 is a circuit diagram showing a level shift circuit according to a first embodiment and circuits related thereto.

FIG. 3 is a circuit diagram showing a level shift circuit according to a second embodiment and circuits related thereto.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Level shift circuit 3 Signal generator 4 1st power supply 8 2nd power supply 9, 10, 11, 12 1st, 2nd, 3rd, and 4th resistor 13 Comparator 14 Constant current source circuit

Claims (3)

[Claims] 1. A first potential (V1) and a second potential (V2)
) Is shifted between a third potential (V3) lower than the first potential (V1) and a fourth potential (V4) lower than the second potential (V2). An input terminal for supplying the input signal, a first power supply terminal for supplying the second potential (V2), and a circuit for supplying the third potential (V3). A second power supply terminal; a first resistor having one end connected to the input terminal; a second resistor connected between the other end of the first resistor and the second power supply terminal; A third resistor having one end connected to the first power supply terminal, a fourth resistor connected between the other end of the third resistor and the second power supply terminal, And a second input terminal, an output terminal, and first and second comparator power supply terminals, wherein the first input terminal is connected to the first and second terminals. Is connected to the interconnection point of the resistors, the second input terminal is connected to the interconnection point of the resistors of the third and fourth, the first comparator power supply terminal of the first
A second power supply terminal, wherein the second comparator power supply terminal is connected to the second power supply terminal, and a comparator is connected between the other end of the third resistor and the second power supply terminal. A constant current source circuit, wherein the resistance value of the first resistor is set substantially equal to the resistance value of the third resistor, and the resistance value of the second resistor is the fourth resistor. And the potential of the second input terminal of the comparator is the same as that of the first input terminal of the comparator when the input signal is at the first potential. The current value of the constant current source circuit is set so as to be between an input potential of the comparator and a second input potential obtained at the first input terminal of the comparator when the input signal is at the second potential. , The output terminal of the comparator and the second power supply terminal Wherein the input signal is level-shifted to obtain an output. 2. A first potential (V1) and a second potential (V2).
) Is shifted between a third potential (V3) higher than the first potential (V1) and a fourth potential (V4) higher than the second potential (V2). An input terminal for supplying the input signal, a first power supply terminal for supplying the first potential (V1), and a circuit for supplying the third potential (V3). A second power supply terminal; a first resistor having one end connected to the input terminal; a second resistor connected between the other end of the first resistor and the second power supply terminal; A third resistor having one end connected to the first power supply terminal, a fourth resistor connected between the other end of the third resistor and the second power supply terminal, And a second input terminal, an output terminal, and first and second comparator power supply terminals, wherein the first input terminal is connected to the first and second terminals. Is connected to the interconnection point of the resistors, the second input terminal is connected to the interconnection point of the resistors of the third and fourth, the first comparator power supply terminal and the second
And a constant current source circuit connected between an interconnection point of the third and fourth resistors and the second comparator power terminal. The resistance of the third resistor is set substantially equal to the resistance of the third resistor, the resistance of the second resistor is set substantially equal to the resistance of the fourth resistor,
When the potential of the second input terminal of the comparator is a first input potential obtained at the first input terminal of the comparator when the input signal is the first potential, the potential of the input signal is the second potential. A current value of the constant current source circuit is set so as to be between a second input potential obtained at the first input terminal of the comparator at the time of a potential, and an output terminal of the comparator and the second comparator A level shift circuit configured to obtain an output obtained by level shifting the input signal between the power supply terminal and a power supply terminal. 3. The level shift circuit according to claim 2, wherein said first power supply terminal is a ground terminal.