Abstract:
A semiconductor integrated circuit device includes a level-shifting circuit, a current mirror circuit and a switch circuit. The level-shifting circuit level-shifts an input signal having a first amplitude to an output signal having a second amplitude. The current mirror circuit charges or discharges an output node of the level-shifting circuit. The switch circuit operates the current mirror circuit during a period from the inversion of the input signal to the inversion of the output signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-268849, filed Sep. 5, 2000, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to a semiconductor integrated circuit device, more particularly, to a level-shifting circuit.  
           [0004]    2. Description of the Related Art  
           [0005]    [0005]FIG. 24 is a circuit diagram showing a conventional level-shifting circuit (4-transistor type).  
           [0006]    As shown in FIG. 24, the level-shifting circuit is constituted by input side NMOS f 1  and f 3  for receiving input signals D, ND (ND is a complementary signal of D), output side PMOS f 4  cascade connected to the NMOS f 1 , and output side PMOS f 2  cascade connected to the NMOS f 3 .  
           [0007]    The inverse operation of such level-shifting circuit is terminated by inverting drain voltage (output signal Q) of the NMOS f 3 , and drain voltage (output signal NQ; NQ is a complementary signal of Q) of the NMOS f 1 , respectively, and inverting ON/OFF of the PMOS f 4  receiving an output signal Q and the PMOS f 2  receiving an inverted output signal NQ in a gate thereof. In this inverse operation, especially in its initial stage, the drain current of the part to become ON by inversion out of the drain currents of NMOS f 1 , f 3 , is required to be sufficiently larger than the drain current of the part to become OFF by inversion out of the drain currents of PMOS f 2 , f 4 .  
           [0008]    Specifically, in the initial stage of the inverse operation, at least the following condition (1) is required between drain current Id 1  of the NMOS f 1  (or f 3 ) and drain current Id 2  of the PMOS f 4  (or f 2 ) cascade connected to the drain current Id 1 : 
           | Id   1 ( Vgs=Vdd−Vss )|&gt;| Id   2 ( Vgs=Vss−vcc )|  (1) 
           [0009]    In other words, under the following condition (2), the level-shifting circuit is not operated. 
           | Id   1 ( Vgs=Vdd−Vss )|≦ Id   2 ( Vgs=Vss−vcc )|  (2) 
           [0010]    For example, in case the maximum voltage vdd of the input signals D, ND is reduced to the level near threshold voltage of the NMOS f 1 , f 3 , the drain current Id 1  of the NMOS f 1  (or f 3 ) decreases to make it difficult to satisfy the above condition (1) and the level-shifting circuit may not be operated.  
           [0011]    Thus, in order to have the level-shifting circuit operate sufficiently, the above condition (1) is required to be satisfied.  
           [0012]    In case the maximum voltage Vcc (Vcc&gt;vdd) of the output signals Q, NQ is elevated, the drain current Id 2  of the PMOS f 4  (or f 2 ) increases to make it difficult to satisfy the above condition (1) similarly and the level-shifting circuit may not be operated.  
           [0013]    Accordingly, conventionally there has been a contrivance made to enlarge element sizes of the NMOS f 1 , f 3 , and the PMOS f 2 , f 4 , in order to satisfy the condition (1) above. For example, in the NMOS f 1 , f 3 , its gate width W is increased, and in the PMOS f 2 , f 4 , its gate length L is increased. By this step, the driving capacity of the NMOS f 1 , f 3  is enhanced, and the drain current Id 1  is enlarged. On the contrary, the drain current Id 2  can be reduced.  
           [0014]    Further, in order to satisfy the condition (1) above, a 6-transistor type level-shifting circuit as shown in FIG. 25 is contrived.  
           [0015]    In the 6-transistor type level-shifting circuit as shown in FIG. 25, PMOS f 13  or PMOS f 14  suppresses the supply of the potential to the source of PMOS f 12  or PMOS f 14  in the initial stage of the inverse operation. For this reason, this transistor may have the drain current in the initial stage of the inverse operation smaller than that of the 4-transistor type level-shifting circuit shown in FIG. 24.  
           [0016]    In the conventional level-shifting circuit, there may be the situation such that, in case the voltage ratio “Vcc/Vdd” between the voltage Vdd prior to the level-shifting and the voltage Vcc after the level-shifting is made larger by lowering the voltage Vdd of the input signals D, ND or elevating the voltage Vcc of the output signals Q, NQ, the level-shifting circuit fails to operate.  
           [0017]    Accordingly, in order to dissolve this situation, contrivance is made to enlarge the element size of MOSFET which constitutes the level-shifting circuit.  
           [0018]    However, in the field of the semiconductor integrated circuit device, there is a requirement of micronization and high integration, and there is a limit to satisfy the condition (1) described above only by the contrivance of enlarging the element size of the MOSFET.  
           [0019]    Besides, contrivance is made of the 6-transistor type level-shifting circuit. In this 6-transistor type level-shifting circuit, in comparison with the 4-transistor type level-shifting circuit, the drain current Id 2  in the initial stage of the inverse operation can be minimized to make it easier to satisfy the above condition (1).  
           [0020]    However, as the 6-transistor type level-shifting circuit basically only suppresses the supply of the electric current to the source of the PMOS f 4  or f 2  in the initial stage of the inverse operation, there remains a limit.  
         BRIEF SUMMARY OF THE INVENTION  
         [0021]    A semiconductor integrated circuit device according to an embodiment of the present invention comprises: a level-shifting circuit configured to level-shift an input signal having a first amplitude to an output signal having a second amplitude different from the first amplitude, the level-shifting circuit having an input node in which the input signal is inputted and an output node in which the output signal is outputted; a current mirror circuit configured to charge or discharge the output node; and a switch circuit configured to operate the current mirror circuit during a period from the inversion of the input signal to the inversion of the output signal. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0022]    [0022]FIG. 1 is a circuit diagram showing a level-shifting circuit according to a first embodiment of the invention;  
         [0023]    [0023]FIG. 2 is a graph showing the effects by the level-shifting circuit according to the first embodiment of the invention;  
         [0024]    [0024]FIGS. 3A and 3B are signal waveform diagrams, respectively;  
         [0025]    [0025]FIG. 4 is a circuit diagram showing a level-shifting circuit according to a second embodiment of the invention;  
         [0026]    [0026]FIG. 5 is a circuit diagram showing a level-shifting circuit according to a third embodiment of the invention;  
         [0027]    [0027]FIG. 6 is a graph showing a level-shifting circuit according to the third embodiment of the invention;  
         [0028]    [0028]FIG. 7 is a circuit diagram showing a level-shifting circuit according to a fourth embodiment of the invention;  
         [0029]    [0029]FIG. 8 is a circuit diagram showing a level-shifting circuit according to a fifth embodiment of the invention;  
         [0030]    [0030]FIG. 9 is a circuit diagram showing a level-shifting circuit according to a sixth embodiment of the invention;  
         [0031]    [0031]FIG. 10 is a circuit diagram showing a level-shifting circuit according to a seventh embodiment of the invention;  
         [0032]    [0032]FIG. 11 is a circuit diagram showing a level-shifting circuit according to an eighth embodiment of the invention;  
         [0033]    [0033]FIG. 12 is a circuit diagram showing a level-shifting circuit according to a ninth embodiment of the invention;  
         [0034]    [0034]FIG. 13 is a circuit diagram showing a level-shifting circuit according to a tenth embodiment of the invention;  
         [0035]    [0035]FIG. 14 is a circuit diagram showing a level-shifting circuit according to an eleventh embodiment of the invention;  
         [0036]    [0036]FIG. 15 is a circuit diagram showing a level-shifting circuit according to a twelfth embodiment of the invention;  
         [0037]    [0037]FIG. 16 is a circuit diagram showing a level-shifting circuit according to a thirteenth embodiment of the invention;  
         [0038]    [0038]FIG. 17 is a circuit diagram showing a level-shifting circuit according to a fourteenth embodiment of the invention;  
         [0039]    [0039]FIG. 18 is a circuit diagram showing a level-shifting circuit according to a fifteenth embodiment of the invention;  
         [0040]    [0040]FIG. 19 is a circuit diagram showing a level-shifting circuit according to a sixteenth embodiment of the invention;  
         [0041]    [0041]FIG. 20 is a circuit diagram showing a level-shifting circuit according to a seventeenth embodiment of the invention;  
         [0042]    [0042]FIG. 21 is a circuit diagram showing a level-shifting circuit according to an eighteenth embodiment of the invention;  
         [0043]    [0043]FIG. 22 is a circuit diagram showing a level-shifting circuit according to a nineteenth embodiment of the invention;  
         [0044]    [0044]FIG. 23 is a circuit diagram showing a level-shifting circuit according to a twentieth embodiment of the invention;  
         [0045]    [0045]FIG. 24 is a circuit diagram showing a conventional level-shifting circuit (4-transistor type);  
         [0046]    [0046]FIG. 25 is a circuit diagram showing a conventional level-shifting circuit (6-transistor type);  
         [0047]    [0047]FIG. 26 is a circuit diagram showing the conventional level-shifting circuit (4-transistor type); and  
         [0048]    [0048]FIG. 27 is a circuit diagram showing the conventional level-shifting circuit (6-transistor type). 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]    Hereinafter, several embodiments of the invention will be explained with reference to the accompanying drawings. In connection with this explanation, throughout the drawings, common portions are indicated with the same reference numerals.  
         [0050]    (First Embodiment)  
         [0051]    [0051]FIG. 1 is a circuit diagram showing a level-shifting circuit according to the first embodiment of the invention.  
         [0052]    As shown in FIG. 1, transistors f 1 , f 2 , f 3 , and f 4  constitute a level-shifting circuit for level shifting to output signals Q, NQ having an amplitude of vss−Vcc level for input signals D, ND having an amplitude of Vss−Vdd level. The potential Vcc is a high potential power source, the potential Vss is a low potential power source (e.g., 0 V), and the potential Vdd is an interim potential between the potential Vcc and the potential Vss. The input signal ND is a complementary input signal which is complementary to the input signal D, e.g., a reversed phase signal of the input signal D, or an inverse signal to the input signal D inverted by an inverter. The output signal NQ is a complementary output signal complementary to the output signal Q, e.g., a reversed phase signal of the output signal Q.  
         [0053]    In the first embodiment of the invention, the transistors f 1 , f 3  are constituted by an N-channel type MOSFET (hereinafter to be abbreviated as NMOS), respectively, and the transistors f 2 , f 4  are constituted by a P-channel type MOSFET (hereinafter to be abbreviated as PMOS), respectively.  
         [0054]    Specifically, as shown in FIG. 1, the low potential power source vss is supplied to the source of the NMOS f 1 , and the input signal D is supplied to its gate. Also, its drain is electrically connected to the complementary output node to which the complementary output signal NQ is outputted (hereinafter to be referred to as complementary output node NQ, for convenience).  
         [0055]    The low potential power source Vss is supplied to the source of the NMOS f 3 , and the complementary input signal ND is supplied to its gate. Also, its drain is electrically connected to an output node to which the complementary output signal Q is outputted (hereinafter to be referred to as output node Q, for convenience).  
         [0056]    The high potential power source Vcc is supplied to the source of the PMOS f 2 , its gate is electrically connected to the output node Q, and its drain is connected to the complementary output node NQ.  
         [0057]    The high potential power source Vcc is supplied to the source of the PMOS f 4 , its gate is electrically connected to the complementary output node NQ, and its drain is connected to the output node Q.  
         [0058]    Transistors f 9 , f 10  constitute a current mirror circuit to charge the output node Q. Similarly, transistors f 11 ,  12  constitute a current mirror circuit to charge the complementary output node NQ.  
         [0059]    In this first embodiment, the transistors f 9  to f 12  are constituted by PMOS, respectively.  
         [0060]    Specifically, as shown in FIG. 1, the high potential power source Vcc is supplied to the source of the PMOS f 9 , and its gate and drain are mutually short-circuited.  
         [0061]    The high potential power source vcc is supplied to the source of the PMOS f 10 , its gate is electrically connected to the gate of the PMOS f 9 , and its drain is electrically connected to the output node Q.  
         [0062]    The high potential power source Vcc is supplied to the source of the PMOS f 11 , and its gate and drain are mutually short-circuited.  
         [0063]    The high potential power source vcc is supplied to the source of the PMOS f 12 , its gate is electrically connected to the gate of the PMOS f 11 , and its drain is electrically connected to the complementary output node NQ.  
         [0064]    The transistors f 5 , f 6  constitute a switch circuit for operating the current mirror circuit constituted by the PMOS f 9  and PMOS f 10  during the period from the inversion of the input signal D from Vss to Vdd to the inversion of the complementary output signal NQ from Vcc to Vss.  
         [0065]    Similarly, the transistors f 7 , f 8  constitute a switch circuit for operating the current mirror circuit constituted by the PMOS f 11  and PMOS f 12  during the period from the inversion of the complementary input signal ND from Vss to Vdd to the inversion of the output signal Q from Vcc to Vss.  
         [0066]    In this first embodiment, the transistors f 5  to f 8  are constituted by NMOS, respectively.  
         [0067]    Specifically, as shown in FIG. 1, the low potential power source Vss is supplied to the source of the NMOS f 5 , and the input signal D is supplied to its gate.  
         [0068]    The source of the NMOS f 6  is electrically connected to the drain of the NMOS f 5 , its gate is electrically connected to the complementary output node NQ, and its drain is electrically connected to the drain of the PMOS f 9 .  
         [0069]    The low potential power source Vss is supplied to the source of the PMOS f 7 , and the complementary input signal ND is supplied to its gate.  
         [0070]    The source of the NMOS f 8  is electrically connected to the drain of the NMOS f 7 , its gate is electrically connected to the output node Q, and its drain is electrically connected to the drain of the PMOS f 11 .  
         [0071]    Now, its basic operation will be explained.  
         [0072]    First, as an initial state, there is assumed a condition where the potential of the input signal D is “Vss”, and the potential of the complementary input signal ND is “Vdd”. Under this initial state, the NMOS f 1  of the level-shifting circuit is “OFF”, and the NMOS f 3  is “ON”. Accordingly, the potential of the output node Q is approximately “Vss”, and the potential of the complementary output node NQ is “Vcc”. In the switch circuit, the NMOS f 5  is “OFF”, the NMOS f 6  is “ON”, the NMOS f 7  is “ON”, and the NMOS f 8  is “OFF”.  
         [0073]    From this initial state, the potentials of the input signals D and ND are inverted, respectively.  
         [0074]    Then, at first, the NMOS f 5  of the switch circuit is turned “ON”. Here, in the initial stage of the inverse operation, the potential of the complementary output node NQ maintains approximately “Vcc”, so that the NMOS f 6  of the switch circuit remains “ON”.  
         [0075]    In this manner, in consequence of both the NMOS f 5  and f 6  being turned “ON”, the PMOS f 9 , f 10  of the current mirror circuit are turned “ON”, and the current mirror circuit starts to operate. Through the operation of the current mirror circuit, the output node Q is charged. In response to this, the PMOS f 2  of the level-shifting circuit is turned “OFF”.  
         [0076]    At this time, because the NMOS f 1  of the level-shifting circuit is “ON”, the complementary output node NQ is discharged, and the potential of the complementary output node NQ is lowered toward “Vss”. In response to this, the PMOS f 4  of the level-shifting circuit is turned “ON” to charge the output node Q. Because of this, the potential of the node Q rises toward “Vcc”.  
         [0077]    Furthermore, when the potential of the complementary output node NQ is lowered to a level equal to or lower than the threshold of the NMOS f 6  of the switch circuit, this NMOS f 6  is turned “OFF” to cause the PMOS f 9 , f 10  of the current mirror circuit to be “OFF”, respectively. As a result, the operation of the current mirror circuit is stopped.  
         [0078]    In the above explanation on the operation, assumption is made on the case of inverting the potential of the input signal D from “Vss” to “Vdd”. However, in case the potential of the input signal D is inverted from “Vdd” to “Vss”, the switch circuit constituted by the NMOS f 7 , f 8  is turned “ON” to operate the current mirror circuit constituted by the PMOS f 11 , f 12  to charge the complementary output node NQ in “Vcc”. And, when the potential of the output node Q is lowered to a level equal to or lower than the threshold of the NMOS f 8  of the switch circuit, this NMOS f 8  is turned “OFF” to stop the operation of the current mirror circuit constituted by the PMOS f 11 , f 12 .  
         [0079]    In the level-shifting circuit according to the first embodiment described above, in the initial stage of the inverse operation, the output node Q or complementary output node NQ is charged by the current mirror circuit. By doing so, the PMOS f 2  or f 4  of the level-shifting circuit is caused to turn “OFF”. Therefore, the maximum voltage ratio “(Vcc−Vss)/(Vdd−Vss)” of the output voltage amplitude to the input voltage amplitude where the operation can be made sufficiently is larger than a conventional level-shifting circuit.  
         [0080]    Furthermore, in the current mirror circuit, after inversion of the potentials of the output node Q and complementary output node NQ, respectively, the operation is stopped by the switch circuit. As a result, the current consumption at the current mirror can be suppressed.  
         [0081]    [0081]FIG. 2 is a graph showing by comparison the minimum input amplitude of the level-shifting circuit according to the first embodiment of the invention with the minimum input amplitude of a conventional level-shifting circuit shown in FIG. 24 and FIG. 25.  
         [0082]    As shown in FIG. 2, in the level-shifting circuit of the invention, even when the input voltage amplitude is lowered to a level near the thresholds of the NMOS f 2 , f 3 , operation can be made sufficiently.  
         [0083]    Though, in this first embodiment, the input signal D is supplied to the gates of the NMOS f 1 , f 5 , respectively, it may be so constituted as to supply a delayed input signal with delay of input signal D to the gate of the NMOS f 1 . In the same manner, to the gate of the NMOS f 3 , a delayed complementary input signal with delay of the complementary input signal ND may be supplied.  
         [0084]    The effect by this is that, by delaying the switching “ON” of, for example, the NMOS f 1 , f 3  of the level-shifting circuit further than “ON” of the NMOS f 5 , f 7  of the switch circuit, the NMOS f 6 , f 8  can be switched “ON” with higher reliability especially in the initial stage of the inverse operation and the current mirror circuit can be more reliably operated.  
         [0085]    Further, in the delay of the input signal D and the complementary input signal ND, the delay time for inversion from Vss to vdd may be set to be longer than the delay time for inversion from Vdd to Vss.  
         [0086]    By doing so, there can be obtained a period in which the input signal D and the complementary input signal ND become simultaneously Vss, respectively, for example, a period in which the NMOS f 1 , f 3  are simultaneously “OFF” can be obtained. Thus, it is possible to eliminate, for example, a period in which the NMOS f 1 , f 3  are simultaneously “ON”, and reduce the throughout current that flows through the period of simultaneously “ON”. By the decrease of the throughout current, increase in power consumption in the integrated circuit is suppressed, being contributory to making the integrated circuit low power consumptive.  
         [0087]    In FIG. 3A, there is shown a typical signal waveform of a level-shifting circuit that has a period in which the NMOS f 1  and f 3  are simultaneously “ON”.  
         [0088]    As shown in FIG. 3A, it is assumed that neither the input signal D nor the complementary input signal ND has any delay time. If, at this time, NMOS f 1  and f 3  have the characteristics in which the turn-off time Toff is longer than the turn-on time Ton, respectively, there is occurred a period in which the NMOS f 1  and f 3  are simultaneously “ON”. In this period, the throughout current runs to cause unnecessary consumption of current.  
         [0089]    On the contrary, as shown in FIG. 3B, in the input signal D and the complementary input signal ND, the delay time TDon for inversion from Vss to Vdd and the delay time TDoff for inversion from Vdd to Vss are respectively set to satisfy the following equation: 
           TD on+ T on−( TD off+ T off)&gt;0 
         [0090]    In this manner, by setting the delay times TDon and TDoff for the input signal D and the complementary input signal ND, as shown in FIG. 3B, the period in which the NMOS f 1  and f 3  are simultaneously “ON” can be made nil to suppress unnecessary current consumption.  
         [0091]    (Second Embodiment)  
         [0092]    [0092]FIG. 4 is a circuit diagram showing a level-shifting circuit according to the second embodiment of the invention.  
         [0093]    As shown in FIG. 4, the difference of the second embodiment from the first embodiment shown in FIG. 1 is in the connecting condition of NMOS f 5 , f 6 , f 7  and f 8  constituting the switch circuit. In the first embodiment, the NMOS f 5 , f 7  are connected to the low potential power source Vss side, but, as shown in this second embodiment, the NMOS f 6 , f 8  may be connected to the low potential power source Vss side.  
         [0094]    In such second embodiment, there can be obtained the same effects as those of the first embodiment.  
         [0095]    (Third Embodiment)  
         [0096]    [0096]FIG. 5 is a circuit diagram showing a level-shifting circuit according to the third embodiment of the invention.  
         [0097]    As shown in FIG. 5, the third embodiment is different from the first embodiment shown in FIG. 1 in that all the conductive types of the transistors f 1  to f 12  are changed to make the high potential power source Vcc to Vdd, and the low potential power source Vss to Vbb (Vbb&lt;Vss; Vbb is for example a negative potential). The level-shifting circuit of this embodiment causes the input signals D, ND having amplitudes of Vss−Vdd level to level-shifting to the output signals Q, NQ having amplitudes of Vbb−Vdd level.  
         [0098]    Specifically, as shown in FIG. 5, the high potential power source Vdd is supplied to the source of the PMOS f 1 , and the input signal D is supplied to its gate. Also, its drain is electrically connected to the complementary output node NQ.  
         [0099]    The high potential power source Vdd is supplied to the source of the PMOS f 3 , and the complementary input signal ND is supplied to its gate. Further, its drain is electrically connected to the output node Q.  
         [0100]    The low potential power source Vbb is supplied to the source of the NMOS f 2 , its gate is electrically connected to the output node Q, and its drain is electrically connected to the complementary output node NQ.  
         [0101]    The low potential power source Vbb is supplied to the source of the NMOS f 4 , its gate is electrically connected to the complementary output node NQ, and its drain is connected to the output node Q.  
         [0102]    The low potential power source Vbb is supplied to the source of the NMOS f 9 , and its gate and drain are mutually short-circuited.  
         [0103]    The low potential power source Vbb is supplied to the source of the NMOS f 10 , its gate is electrically connected to the gate of the NMOS f 9 , and its drain is electrically connected to the output node Q.  
         [0104]    The low potential power source Vbb is supplied to the source of the NMOS f 11 , and its gate and drain are mutually short-circuited.  
         [0105]    The low potential power source Vbb is supplied to the source of the NMOS f 12 , its gate is electrically connected to the gate of the NMOS f 11 , and its drain is electrically connected to the complementary output node NQ.  
         [0106]    The high potential power source vdd is supplied to the source of the PMOS f 5 , and the input signal D is supplied to its gate.  
         [0107]    The source of the PMOS f 6  is electrically connected to the drain of the PMOS f 5 , its gate is electrically connected to the complementary output node NQ, and its drain is electrically connected to the drain of the NMOS f 9 .  
         [0108]    The high potential power source Vdd is supplied to the source of the PMOS f 7 , and the complementary input signal ND is supplied to its gate.  
         [0109]    The source of the PMOS f 8  is electrically connected to the drain of the PMOS f 7 , its gate is electrically connected to the output node Q, and its drain is electrically connected to the drain of the NMOS f 11 .  
         [0110]    Next, its basic operation will be explained.  
         [0111]    First, as an initial state, there is assumed a condition where the potential of the input signal D is “Vdd”, and the potential of the complementary input signal ND is “Vss”. Under this initial state, the PMOS f 1  of the level-shifting circuit is “OFF”, and the PMOS f 3  is “ON”. Accordingly, the potential of the output node Q is “Vdd”, and the potential of the complementary output node NQ is “Vbb”. In the switch circuit, the PMOS f 5  is “OFF”, the PMOS f 6  is “ON”, the PMOS f 7  is “ON”, and the PMOS f 8  is “OFF”.  
         [0112]    From this initial state, potentials of the input signals D and ND are inverted, respectively.  
         [0113]    Then, at first, the PMOS f 5  of the switch circuit is turned “ON”. Here, in the initial stage of the inverse operation, the potential of the complementary output node NQ maintains approximately “Vbb”, so that the PMOS f 6  of the switch circuit remains “ON”.  
         [0114]    In this manner, in consequence of both the PMOS f 5  and f 6  being turned “ON”, the PMOS f 9 , f 10  of the current mirror circuit are turned “ON”, and the current mirror circuit starts to operate. Through the operation of the current mirror circuit, the output node Q is discharged. In response to this, the NMOS f 2  of the level-shifting circuit is turned “OFF”.  
         [0115]    At this time, because the PMOS f 1  of the level-shifting circuit is “ON”, the complementary output node NQ is charged, and the potential of the complementary output node NQ rises toward “Vdd”. In response to this, the NMOS f 4  of the level-shifting circuit is turned “ON” to discharge the output node Q. Because of this, the potential of node Q is lowered toward “Vbb”.  
         [0116]    Furthermore, when the potential of the output node NQ rises, and the inter-gate/source voltage |Vgs| of the PMOS f 6  of the switch circuit NMOS f 6  comes to a level equal to or lower than the absolute amount of the threshold of this PMOS f 6 , the PMOS f 6  is turned “OFF” to cause the NMOS f 9 , f 10  of the current mirror circuit to be “OFF”, respectively. As a result, the operation of the current mirror circuit is stopped.  
         [0117]    In the above explanation on the operation, assumption is made on the case of inverting the potential of the input signal D from “Vdd” to “Vss”. However, in case the potential of the input signal D is inverted from “Vss” to “Vdd”, the switch circuit constituted by the PMOS f 7 , f 8  is turned “ON” to operate the current mirror circuit constituted by the NMOS f 11 , f 12  to discharge the complementary output node NQ to “Vbb”. And, when the potential of the output node Q rises, and the inter-gate/source voltage |vgs| of the PMOS f 8  of the switch circuit NMOS f 8  comes to a level equal to or lower than the absolute amount of the threshold of this PMOS f 8 , the PMOS f 8  is turned “OFF” to stop the operation of the current mirror circuit constituted by the NMOS f 11 , f 12 .  
         [0118]    In the level-shifting circuit according to the third embodiment described above, in the initial stage of the inverse operation, by the current mirror circuit, the output node Q or complementary output node NQ is discharged. By doing so, the NMOS f 2  or f 4  of the level-shifting circuit is caused to turn “OFF”. Therefore, the maximum voltage ratio “(Vbb−Vss)/(Vdd−Vss)” of the output voltage amplitude to the input voltage amplitude where the operation can be made sufficiently is larger than a conventional level-shifting circuit.  
         [0119]    Furthermore, in the current mirror circuit, after inversion of the potentials of the output node Q and the complementary output node NQ, respectively, the operation is stopped by the switch circuit. As a result, the current consumption at the current mirror can be suppressed.  
         [0120]    [0120]FIG. 6 is a graph showing by comparison the minimum input amplitude of the level-shifting circuit according to the third embodiment of the invention with the minimum input amplitude of a conventional level-shifting circuit shown in FIG. 26 (4-transistor type), and conventional level-shifting circuit shown in FIG. 27 (6-transistor type).  
         [0121]    As shown in FIG. 6, in the level-shifting circuit of the invention, even when the input voltage amplitude is lowered to a level near the absolute value of thresholds of the PMOS f 1 , f 3 , the operation can be made sufficiently.  
         [0122]    (Fourth Embodiment)  
         [0123]    [0123]FIG. 7 is a circuit diagram showing a level-shifting circuit according to the fourth embodiment of the invention.  
         [0124]    As shown in FIG. 7, the difference of the fourth embodiment from the third embodiment shown in FIG. 5 is in the connecting condition of PMOS f 5 , f 6 , f 7  and f 8 . In the third embodiment, the PMOS f 5 , f 7  are connected to the high potential power source Vdd side, but, as shown in this fourth embodiment, the PMOS f 6 , f 8  may be connected to the high potential power source Vdd side.  
         [0125]    In the fourth embodiment, there can be obtained the same effects as those of the third embodiment.  
         [0126]    (Fifth Embodiment)  
         [0127]    [0127]FIG. 8 is a circuit diagram showing a level-shifting circuit according to the fifth embodiment of the invention.  
         [0128]    As shown in FIG. 8, the fifth embodiment is different from the first embodiment shown in FIG. 1 in that the PMOS f 9 , f 10  are of the PNP bipolar transistors.  
         [0129]    In case the PMOS f 9 , f 10  are of the PNP bipolar transistors, there can be expected such effects that, for example, the driving capacity of the current mirror circuit is improved, and the charge capacity of the output node Q is improved.  
         [0130]    (Sixth Embodiment)  
         [0131]    [0131]FIG. 9 is a circuit diagram showing a level-shifting circuit according to the sixth embodiment of the invention.  
         [0132]    As shown in FIG. 9, the sixth embodiment is different from the first embodiment shown in FIG. 1 in that the PMOS f 9 , f 10 , f 11  and f 12  are of the PNP bipolar transistors.  
         [0133]    In this case as well, in the same manner as in the fifth embodiment, there can be expected such effects that, for example, the driving capacity of the current mirror circuit is improved, and the charge capacities of the output node Q and complementary output node NQ are improved.  
         [0134]    (Seventh Embodiment)  
         [0135]    [0135]FIG. 10 is a circuit diagram showing a level-shifting circuit according to the seventh embodiment of the invention.  
         [0136]    AS shown in FIG. 10, the seventh embodiment is different from the third embodiment shown in FIG. 5 in that the NMOS f 9 , f 10  are of the NPN bipolar transistors.  
         [0137]    In case the NMOS f 9 , f 10  are of the NPN bipolar transistors, there can be expected such effects that, for example, the driving capacity of the current mirror circuit is improved, and the discharge capacity of the output node Q is improved.  
         [0138]    (Eighth Embodiment)  
         [0139]    [0139]FIG. 11 is a circuit diagram showing a level-shifting circuit according to the eighth embodiment of the invention.  
         [0140]    As shown in FIG. 11, the eighth embodiment is different from the third embodiment shown in FIG. 5 in that the NMOS f 9 , f 10 , f 11 , and f 12  are of the NPN bipolar transistors.  
         [0141]    In this case as well, in the same manner as in the seventh embodiment, there can be expected such effects that, for example, the driving capacity of the current mirror circuit is improved, and the discharge capacities of the output node Q and complementary output node NQ are improved.  
         [0142]    (Ninth Embodiment)  
         [0143]    [0143]FIG. 12 is a circuit diagram showing a level-shifting circuit according to the ninth embodiment of the invention.  
         [0144]    As shown in FIG. 12, the ninth embodiment is different from the second embodiment shown in FIG. 4 in that the NMOS f 9 , f 10  are of the PNP bipolar transistors. This modification is of course acceptable.  
         [0145]    (Tenth Embodiment)  
         [0146]    [0146]FIG. 13 is a circuit diagram showing a level-shifting circuit according to the tenth embodiment of the invention.  
         [0147]    As shown in FIG. 13, the tenth embodiment is different from the second embodiment shown in FIG. 4 in that PMOS f 9 , f 10 , f 1 , and f 12  are of the PNP bipolar transistors. This modification is of course acceptable.  
         [0148]    (Eleventh Embodiment)  
         [0149]    [0149]FIG. 14 is a circuit diagram showing a level-shifting circuit according to an eleventh embodiment of the invention.  
         [0150]    As shown in FIG. 14, the eleventh embodiment is different from the fourth embodiment shown in FIG. 7 in that the NMOS f 9 , f 10  are of the NPN bipolar transistors. This modification is of course acceptable.  
         [0151]    (Twelfth Embodiment)  
         [0152]    [0152]FIG. 15 is a circuit diagram showing a level-shifting circuit according to the twelfth embodiment of the invention.  
         [0153]    As shown in FIG. 15, the twelfth embodiment is different from the fourth embodiment shown in FIG. 7 in that the NMOS f 9 , f 10 , f 11 , and f 12  are of the NPN bipolar transistors. This modification is of course acceptable.  
         [0154]    (Thirteenth Embodiment)  
         [0155]    [0155]FIG. 16 is a circuit diagram showing a level-shifting circuit according to the thirteenth embodiment of the invention.  
         [0156]    As shown in FIG. 16, the difference of the thirteenth embodiment from the first embodiment shown in FIG. 1 is in the connecting condition of the NMOS f 5 , f 6 . In the first embodiment, the NMOS f 5  is connected to the low potential power source Vss side, but, as shown in this thirteenth embodiment, the NMOS f 6  may be connected to the low potential power source Vss side.  
         [0157]    (Fourteenth Embodiment)  
         [0158]    [0158]FIG. 17 is a circuit diagram showing a level-shifting circuit according to the fourteenth embodiment of the invention.  
         [0159]    As shown in FIG. 17, the fourteenth embodiment is different from the thirteenth embodiment shown in FIG. 16 in that the PMOS f 9 , f 10  are of the PNP bipolar transistors. This modification is of course acceptable.  
         [0160]    (Fifteenth Embodiment)  
         [0161]    [0161]FIG. 18 is a circuit diagram showing a level-shifting circuit according to the fifteenth embodiment of the invention.  
         [0162]    As shown in FIG. 18, the fifteenth embodiment is different from the thirteenth embodiment shown in FIG. 16 in that the PMOS f 11 , f 12  are of the PNP bipolar transistors. This modification is of course acceptable.  
         [0163]    (Sixteenth Embodiment)  
         [0164]    [0164]FIG. 19 is a circuit diagram showing a level-shifting circuit according to the sixteenth embodiment of the invention.  
         [0165]    As shown in FIG. 19, the sixteenth embodiment is different from the thirteenth embodiment shown in FIG. 16 in that the PMOS f 9 , f 10 , f 11 , and f 12  are of the PNP bipolar transistors. This modification is of course acceptable.  
         [0166]    (Seventeenth Embodiment)  
         [0167]    [0167]FIG. 20 is a circuit diagram showing a level-shifting circuit according to the seventeenth embodiment of the invention.  
         [0168]    As shown in FIG. 20, the difference of the seventeenth embodiment from the third embodiment shown in FIG. 5 is in the connecting condition of the PMOS f 5 , f 6 . In the third embodiment, the PMOS f 5  is connected to the high potential power source Vcc side, but, as shown in this seventeenth embodiment, the PMOS f 6  may be connected to the high potential power source Vcc side.  
         [0169]    (Eighteenth Embodiment)  
         [0170]    [0170]FIG. 21 is a circuit diagram showing a level-shifting circuit according to the eighteenth embodiment of the invention.  
         [0171]    As shown in FIG. 21, the eighteenth embodiment is different from the seventeenth embodiment shown in FIG. 20 in that the NMOS f 9 , f 10  are of the NPN bipolar transistors. This modification is of course acceptable.  
         [0172]    (Nineteenth Embodiment)  
         [0173]    [0173]FIG. 22 is a circuit diagram showing a level-shifting circuit according to the nineteenth embodiment of the invention.  
         [0174]    As shown in FIG. 22, the nineteenth embodiment is different from the seventeenth embodiment shown in FIG. 20 in that the NMOS f 11 , f 12  are of the NPN bipolar transistors. This modification is of course acceptable.  
         [0175]    (Twentieth Embodiment)  
         [0176]    [0176]FIG. 23 is a circuit diagram showing a level-shifting circuit according to the twentieth embodiment of the invention.  
         [0177]    As shown in FIG. 23, the twentieth embodiment is different from the seventeenth embodiment shown in FIG. 20 in that the NMOS f 9 , f 10 , f 11 , and f 12  are of the NPN bipolar transistors. This modification is of course acceptable.  
         [0178]    As described above, this invention has been explained by way of the first to twentieth embodiments, but this invention is not limited to those embodiments. In the practice of the invention, various modifications are applicable within the range without departing from the purport of the invention.  
         [0179]    For example, in the foregoing embodiment, there is shown an example of changing the transistors constituting the current mirror circuit from the insulating gate type FET, e.g., MOSFET, to the bipolar transistor. However, change of another transistor to the bipolar transistor is also possible. Especially, it is useful to change the transistors f 1 , f 3  of the level-shifting circuit and transistors f 5 , f 7  of the switch circuit which require especially sufficient driving capacities to the bipolar transistors. This is because, by improving the driving capacities of these transistors f 1 , f 3 , f 5 , and f 7 , even when the voltage Vdd prior to the level shift is lowered, advantageous actions are given to the attainment of the object to operate the level-shifting circuit sufficiently.  
         [0180]    It is of course possible to practice the embodiments given above either solely or in appropriate combination.  
         [0181]    Furthermore, the above embodiments include the inventions of various stages, and it is possible to extract the inventions of various stages by appropriate combinations of plural constituting conditions disclosed in each embodiment.  
         [0182]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the sprit or scope of the general inventive concept as defined by the appended clams and their equivalents.