Abstract: A circuit includes a differential circuit having at least to two inputs, a first variable impedance circuit, and a second variable impedance circuit. The first variable impedance circuit is between a first branch of the differential circuit and an output. The first variable impedance circuit provides a first variable impedance. The a second variable impedance circuit is between a second branch of the differential circuit and the output. The second variable impedance circuit provides a second variable impedance. The first variable impedance and the second variable impedance vary in accordance with a voltage difference between the two inputs.

Abstract: According to one embodiment, a level conversion circuit includes an intermediate voltage generating portion to generate an intermediate voltage between a first voltage and a second voltage upon receiving the first voltage and the second voltage higher than the first voltage. A buffer portion operates on the intermediate voltage upon receiving a first signal and an inverted first signal of a first amplitude corresponding to the first voltage. The buffer portion outputs a second signal and an inverted second signal having a second amplitude corresponding to the intermediate voltage. A level shift portion operates on the second voltage upon receiving the second signal and the inverted second signal, and outputs a third signal and an inverted third signal having a third amplitude corresponding to the second voltage.

Abstract: An apparatus is disclosed. In a particular embodiment, the apparatus includes a a dynamic circuit structure that includes a dynamic node coupling a precharge circuit, a discharge circuit, and a gated keeper circuit. The gated keeper circuit is enabled by a signal from a discharge delay tracking circuit.

Abstract: A level shifter configured to generate an output voltage having a shifted voltage level relative to an input voltage, the level shifter includes a first gain module having a first resistance, the first gain module to generate a first voltage based on the input voltage and the first resistance. A load module having a second resistance, the load module to generate a second voltage based on the first voltage and the second resistance. A second gain module having a third resistance, the second gain module to generate a third voltage based on one of the second voltage and the third resistance or the first voltage and the third resistance; and an output driver to output the output voltage having the shifted voltage level based on the third voltage.

Abstract: Provided is tamper detection line circuitry for an authentication integrated circuit for use in authenticating an integrated circuit. The tamper detection line circuitry includes a source of pseudo-random bits, and an XOR gate with two inputs and an output in signal communication with flash memory erase and reset circuits. A complete erasure of the memory is triggered by a 0 from the XOR gate. The circuitry also includes first and second paths arranging the source and XOR gate in signal communication with each other, as well as a number of triggers connected to the respective paths, each trigger configured to detect a physical attack on the authentication integrated circuit, said triggers configured to pull a respective path to 0 if a physical attack is detected.

Abstract: In one embodiment, a power domain isolation interface is disclosed. The interface has a level shifter having a signal input coupled to a first power domain and a memory element. The memory element has a signal input coupled to an output of the level shifter, an output coupled to a second power domain, and a hold enable input, wherein the memory element is configured to hold an input state when the hold enable input becomes asserted.

Abstract: A level shift circuit includes a control logic circuit, a plurality of level shift output buffers and a plurality of charge sharing circuits. The control logic circuit receives input clock pulse signals and a charge sharing signal and acquires voltage level information of each received signal. Each output buffer amplifies a corresponding input clock pulse signal and determines whether to output a signal according to the acquired information of the charge sharing signal. Each charge sharing circuit determines whether to be turned on according to the acquired information of a corresponding input clock pulse signal. When a charge sharing circuit is turned on, the output terminal of a corresponding output buffer and a predetermined voltage level are coupled to each other by the charge sharing circuit, so as to perform the charge sharing operation. Furthermore, a corresponding liquid crystal display device and a corresponding charge sharing method are also provided.

Abstract: A method and apparatus are disclosed to control one or more input output (I/O) pads. An input signal is translated to an output signal having a desired logic level using a first latch loop. The state of the first latch loop is maintained by a second latch loop, integrated with the first latch loop, when a latching indication is received. The integration between the first latch loop and the second latch loop is such that the second latch loop creates an input-output connection if transmission gates in the second latch loop are conductive, and disables the input-output connection if the transmission gates are not conductive.

Abstract: A level shifter receives an input signal of either a first lower voltage or a first upper voltage which form a voltage pair, and level-shifts the input signal to output an output signal of either a second lower voltage or a second upper voltage. An SR flip-flop generates an output signal which is switched to the second upper voltage upon receiving a positive edge via its set terminal, and is switched to the second lower voltage upon receiving a positive edge via its reset terminal. An AND gate generates the logical AND of a feedback signal having the inverted logical level of the output signal of the SR flip-flop and the input signal, which is output to the set terminal of the SR flip-flop. A NOR gate generates the logical NOR of the feedback signal and the input signal, which is output to the reset terminal of the SR flip-flop.

Abstract: A flip-flop circuit with an internal level shifter includes an input stage, a clock input stage, an output stage and a level shifting stage. The output stage generates an output signal based on an input signal received by the input stage and a clock signal received by the clock input stage. The level shifting stage shifts-up the voltage level of the output signal.

Abstract: A semiconductor device includes a swing level shifting unit configured to use a first power supply voltage as a power supply voltage, receive a CML clock swinging around a first voltage level, and shift a swing reference voltage level of the CML clock to a second voltage level lower than the first voltage level, and a CML clock transfer buffering unit configured to use a second power supply voltage as a power supply voltage and buffer the CML clock, which is transferred from the swing level shifting unit and swings around the second voltage level.

Abstract: A semiconductor device includes a swing level shifting unit configured to use a first power supply voltage as a power supply voltage, receive a CML clock swinging around a first voltage level, and shift a swing reference voltage level of the CML clock to a second voltage level lower than the first voltage level, and a CML clock transfer buffering unit configured to use a second power supply voltage as a power supply voltage and buffer the CML clock, which is transferred from the swing level shifting unit and swings around the second voltage level.

Abstract: An integrated circuit includes first and second voltage domains. The first voltage domain is associated with a positive voltage supply grid and the second voltage domain is associated with a selectably on voltage supply grid. A switch is used to selectably switch on and off the selectably on voltage supply grid to power the second voltage domain. A buffer cell cluster of at least on initial buffer cell and a pair of insulator cells is coupled to the positive voltage supply grid electrically independent of the nodes of a switch and is capable of buffering a feed-through signal having a logic one voltage level defined substantially at the voltage level of the positive voltage supply grid. The buffer cell cluster has two distal ends. buffer cell cluster, at one distal end, is coupled to a first insulator cell of the pair of cells while, at the other distal end, the buffer cell cluster is coupled to a second insulator cell of the pair of the cells.

Abstract: A semiconductor device is capable of stably maintaining a voltage level of a shield line, even when a voltage level of an adjacent line is varied. The semiconductor device includes normal lines arranged for transfer of signals, a shield line arranged adjacently to the normal lines, a level shifting circuit for receiving an input signal swinging between a power supply voltage level and a ground voltage level, and shifting the input signal to an output signal swing between the power supply voltage level and a low voltage level lower than the ground voltage level by a predetermined level to output a shifted signal via the shield line, and a signal input unit for transferring the signal provided via the shield line to an output node.

Abstract: Level shifting circuitry and corresponding enable signal generating circuitry provides improved leakage current control while eliminating the need for supplying reference voltage input in the enable signal generator. The level shifting circuitry is a type of cascode free level shifting circuit that does not include cascode transistors as in the prior art but instead utilizes cross coupled logic to provide level shifting while also utilizing enable signal controlled transistors to control leakage current through the cross coupled logic during power up sequencing. The level shifting circuitry provides improved leakage current limiting structure for power up sequencing whether a lower level supply voltage ramps up faster than the higher level supply voltage or vice a versa.

Abstract: A 2×VDD-tolerant input/output (I/O) buffer circuit with process, voltage, and temperature (PVT) compensation suitable for CMOS technology is disclosed. A 2×VDD-tolerant I/O buffer with a PVT compensation circuit is implemented with novel 2×VDD-tolerant logic gates. Output slew rate variations can be kept within smaller ranges to match maximum and minimum timing specifications. A 2×VDD tolerant logic circuit for implementing the I/O buffer is also disclosed.

Abstract: A circuit arrangement for shifting a voltage level comprises a data-current converter (2) that is connected to a first connection (K1) and that has an input for feeding a digital input data signal (DIN), a first output for providing a current (I), and also a second output for providing a reference current (I1), and a current-data converter (3) that is connected to a second connection (K2) and that has a first input for feeding the current (I), a second input for feeding the reference current (I1), and also an output for providing a digital output data signal (DOUT). Here, a voltage level of the digital output data signal (DOUT) is different from a voltage level of the digital input data signal (DIN). In addition, a method for shifting a voltage level is provided.

Abstract: Disclosed herein is an apparatus for outputting complementary signals using bootstrapping technology. The apparatus for outputting complementary signals includes a precharaged logic block, one or more output nodes, and a bootstrapping circuit block. The precharged differential logic block generates a differential signal depending on an input signal. The one or more output nodes output the complementary signals depending on the differential signal. The bootstrapping circuit block is shared by the one or more output nodes, and amplifies the complementary signals.

Abstract: A level shifter circuit converts a signal generated by an internal circuit which operates with a first power supply, into a signal by a second power supply having voltage higher than that of the first power supply. The voltages at substrate terminals of two NMOS transistors, to which complementary two signals by the first power supply are input, is boosted to voltage higher than circuit ground potential in a period in which a voltage level of one of the two input signals and a voltage level of an output signal by the second power supply do not coincide with each other.

Abstract: A level shifter for integrated circuits includes input stage transistors, reference stage transistors, a cascode stage coupled to the input stage and the reference stage transistors and a pair of comparators. The cascode stage generates a first cascode output and a second cascode output. The input stage transistors selectively conduct a low reference voltage as the first cascode output based on a pair of inputs provided to the input stage transistors. The reference stage transistors selectively conduct a high reference voltage as the second cascode output based on a first comparator output and a second comparator output. The pair of comparators generate the first and the second comparator outputs based on the first and the second cascode outputs.

Abstract: A shift register comprising at least one shift register unit. The shift register unit comprises an input unit, at least one first TFT, and at least one second TFT. The input unit receives an input signal from the input terminal and outputs a switching control signal in accordance with a first clock signal. The gate of the first TFT is for receiving the switching control signal, the drain of the first TFT is for receiving a second clock signal, and the source of the first TFT is coupled to the output terminal. The gate and drain of the second TFT are coupled to the output terminal, and the source of the second TFT is coupled to the input unit.

Abstract: A 2×VDD-tolerant input/output (I/O) buffer circuit with process, voltage, and temperature (PVT) compensation suitable for CMOS technology is disclosed. A 2×VDD-tolerant I/O buffer with a PVT compensation circuit is implemented with novel 2×VDD-tolerant logic gates. Output slew rate variations can be kept within smaller ranges to match maximum and minimum timing specifications. A 2×VDD tolerant logic circuit for implementing the I/O buffer is also disclosed.

Abstract: Provided are a level shifter and a semiconductor device having an OFF-chip driver (OCD) using the same. The level shifter includes a plurality of series connected logic gates receiving a first-state input signal having a first power supply voltage level and generating a level-shifted first-state output signal having a second power supply voltage level. The logic gates receive as power supply voltages at least one intermediate power supply voltage having at least one voltage level intermediate between the first power supply voltage level and the second power supply voltage level, and an intermediate power supply voltage applied to the present logic gate is equal to or higher than an intermediate power supply voltage applied to the previous logic gate.

Abstract: A semiconductor device includes a first semiconductor chip operating at a first power supply voltage and a second semiconductor chip operating at a second power supply voltage lower than the first power supply voltage to supply the second power supply voltage to the first semiconductor chip. The semiconductor chips according to the present invention are conveniently used for fabrication of the semiconductor device. The first semiconductor chip includes an output circuit including a first transistor and a second transistor, interconnected in series and turned on or off complementarily. The output circuit outputs a signal to a first external output terminal. The first semiconductor chip also includes a third transistor connected in series with the first and second transistors and having a gate electrode connected to a second output terminal.

Abstract: A level converter comprising an input circuit, coupled to a low power source and a first high power source, which generates a complementary first signal and second signal; and a shift circuit that outputs an output signal generated by shifting a voltage level of the input signal, the shift circuit including: a latch circuit having: a first inverter circuit provided in a first path between a second high power source and the low power source; and a second inverter circuit provided in a second path between the second high power source and the low power source, wherein the latch circuit is formed by coupling an input terminal and an output terminal of the first inverter circuit and the second inverter circuit; a first transistor coupled to the first path; and a second transistor coupled to the second path.

Abstract: A test circuit that compares test results between two tests with different local supply voltages is provided. The output of each stage of the logic circuits is stored in a first register of each test circuit. Each test is performed with a critical test vector and a local supply voltage that decreases from test to test. The outputs of successive tests are compared in each test circuit. The tests are performed iteratively with successive reduction in the value of the local supply voltage until at least one stage of the logic circuits produces non-matching results between the first and second register. The voltage immediately before producing such non-matching results is the minimum operational voltage for the local voltage island.

Abstract: A system and method of performing off chip drive (OCD) and on-die termination (ODT) are provided. A common pull-up network composed of transistors and a common pull-down network composed of transistors are employed to implement both of these functions. In drive mode, the pull-up network is configured to produce a calibrated drive impedance when an “on” output is to be generated, and the pull-up network is configured to produce a calibrated drive impedance when an “off” output is to be generated. In termination mode, the pull-up network and the pull-down network are configured to produce a calibrated pull-up resistance and pull-down resistance respectively such that together, they form a split termination.

Abstract: An IO interface circuit for use in a high voltage tolerant application is provided. The IO interface circuit includes a signal pad and at least a first parasitic bipolar transistor having an emitter adapted for connection to a voltage return of the interface circuit, a base adapted to receive a first control signal, and a collector connected directly to the signal pad in an open collector configuration. The interface circuit further includes a MOS control circuit coupled to the parasitic bipolar transistor and being operative to generate the first control signal. The IO interface circuit may further include an active pull-up circuit connected between a voltage supply of the interface circuit and the signal pad.

Abstract: An arrangement and method for signal transmission between different voltage domains is disclosed. One embodiment provides a first signal processing unit receiving a first supply voltage. A second signal processing unit receives a second supply voltage, the first supply voltage and the second supply voltage overlap each other in a first overlap range. A third signal processing unit receives a third supply voltage, the second supply voltage and the third supply voltage overlap each other in a second voltage overlap range. A first information signal from the first signal processing unit is transmitted to the second signal processing unit. A second information signal dependent on the first information signal from the second signal processing is transmitted to the third signal processing unit.

Abstract: An interface for use of device whose core circuitry operates in one voltage domain, but exchanges signal with another device (or “host”) according a different voltage domain, and the use of such an interface for supplying data using a double data rate (DDR) transfer, is presented. One concrete example of this situation is a memory card, where the internal circuitry uses one voltage range for its core operating voltages, but exchanges signals with a host using different, input/output voltage range. According to a general set of aspects, the interface receives data signals from the device at the device's core operating voltage domain, individually level shifts these to the input/output voltage domain, and then combines them into a DDR signal for transfer to the host device, where a (non-level shifted) clock signal from the host device is used as the select signal to form the DDR data signal.

Abstract: A level shift circuit shifts a first voltage level to a second voltage level that is different from the first voltage level. The level shift circuit includes a set-level circuit 21 configured to detect and transmit a set signal that is used to set a logic voltage state based on the second voltage level, a reset-level circuit 22 configured to detect and transmit a reset signal that is used to reset the logic voltage state based on the second voltage level, and a reference-level circuit C3 configured to provide a reference signal that is used to detect the set signal and reset signal based on the second voltage level. The set-level circuit, reset-level circuit, and reference-level circuit transmit signals from the first voltage level to the second voltage level through capacitors C1, C2, and C3, respectively.

Abstract: A logic circuit with a simple configuration and good current efficiency is provided. The logic circuit includes a two-terminal bistable switching element (1) having characteristics which maintain states, a first switching element (25) one end of which is connected to one terminal of the two-terminal bistable switching element (1), a second switching element (29) one end of which is connected to the other terminal of the two-terminal bistable switching element (1) via a resistance element (27), and first and second pulse input terminals (33, 37) respectively connected to the one terminal and the other terminal of the two-terminal bistable switching element (1). A bias voltage is applied across the other end of the first switching element (25) and the other end of the second switching element (27), and a trigger pulse is input from the first and second pulse input terminals (33, 37).

Abstract: A circuit for converting a lower voltage logical signal to a higher voltage. The circuit comprises a current mirror structure having first and second branches, each comprising at least a first transistor of a first kind, an input transistor of a second kind, and a second transistor of the first kind coupled between them. The first transistors are arranged as a current mirror. The input transistors are driven using a logical signal at the lower voltage, controlling the current mirror structure to output a corresponding logical signal at the higher voltage. The second transistors are driven by an intermediate reference voltage so as to reduce the operating voltage of the third transistors. The first kind is tolerant of a higher operating voltage than the second kind.

Abstract: A level converter for providing an output signal at a circuit output based on an input signal includes an output coupling circuit formed to provide an output signal based on a first partial output signal and a second partial output signal, a driver circuit formed to provide the second partial output signal such that the second partial output signal is switchable between two different signal levels depending on the state of the input signal, wherein an input of the driver circuit is capacitively coupled to the input of the level converter in order to allow for switching between the signal levels of the second partial output signal by the capacitive coupling in response to a change in the state of the input signal, and a holding circuit formed to keep the state of the second partial output signal constant in case of a constant state of the input signal.

Abstract: High voltage logic circuits that can handle digital input and output signals having a larger voltage range are described. In an exemplary design, a high voltage logic circuit includes an input stage, a second stage, and an output stage. The input stage receives at least one input signal and provides (i) at least one first intermediate signal having a first voltage range and (ii) at least one second intermediate signal having a second voltage range. The second stage receives and processes the first and second intermediate signals based on a logic function and provides (i) a first drive signal having the first voltage range and (ii) a second drive signal having the second voltage range. The output stage receives the first and second drive signals and provides an output signal having a third voltage range, which may be larger than each of the first and second voltage ranges.

Abstract: A level-shifting amplifier is provided for level-shifting an input signal with a voltage magnitude that exceeds a supply voltage of the amplifier. In operation, the amplifier has an input impedance of greater than 100 MOhms.

Abstract: According to an aspect of the present invention, there is provided a semiconductor device including: a first circuit portion including: a first circuit that is connected between a first high-side power line and a low-side power line and that outputs a second signal based on a first signal input thereto; and a second circuit portion including: a first transistor that is connected between a second high-side power line and a node and that has a normally-on characteristic; a second circuit that is connected between the node and the low-side power line and that outputs a third signal based on the second signal input thereto.

Abstract: Disclosed is a level shift circuit that includes a first level shifter which is connected between an output terminal and a first power supply terminal that supplies a first voltage and sets the output terminal to a level of the first voltage when an input signal received at an input terminal assumes a first value; a second level shifter which is connected between the output terminal and a second power supply terminal that supplies a second voltage and sets the output terminal to a level of the second voltage when the input signal assumes a complementary value of the first value; and a feedback control unit that performs control of deactivating the first level shifter during a predetermined time interval including a point of time when the input signal is supplied when it is detected that the output terminal immediately before the input signal is received at the input terminal assumes the first voltage level.

Abstract: According to one embodiment, a level conversion circuit includes an intermediate voltage generating portion to generate an intermediate voltage between a first voltage and a second voltage upon receiving the first voltage and the second voltage higher than the first voltage. A buffer portion operates on the intermediate voltage upon receiving a first signal and an inverted first signal of a first amplitude corresponding to the first voltage. The buffer portion outputs a second signal and an inverted second signal having a second amplitude corresponding to the intermediate voltage. A level shift portion operates on the second voltage upon receiving the second signal and the inverted second signal, and outputs a third signal and an inverted third signal having a third amplitude corresponding to the second voltage.

Abstract: Provided is a novel keeper circuit with a pull-up device whose strength changes for different operating supply levels so that the pull-up device is weaker for smaller supply levels and stringer for higher supply levels.

Abstract: A calibration circuit includes a gain control device configured to adjust a reference voltage to a predetermined level according to a variable gain; and a calibration device configured to update a calibration code by comparing a voltage generated by resistors and the reference voltage adjusted to the predetermined level by the gain control device, wherein the resistors are individually controlled to be turned on by the calibration code.

Abstract: A semiconductor integrated circuit device including an I/O circuitry capable of low-voltage high-speed operation at low cost is provided. In the I/O circuitry, when an I/O voltage (for example, 3.3 V) is lowered to a predetermined voltage (for example, 1.8 V), portions causing a speed deterioration are a level conversion unit and a pre-buffer unit for driving a main large-sized buffer. In view of this, a high voltage is applied to a level up converter and a pre-buffer circuit. By doing so, it is possible to achieve an I/O circuitry capable of low-voltage high-speed operation at low cost.

Abstract: Described herein is the method and apparatus for generating symmetrical level shifted signals by a symmetrical level shifter. The symmetrical level shifter comprises an edge detector operable to generate transition edge based pulses from an input signal based on a first power supply level; a voltage level shifter, coupled with the edge detector, operable to convert the transition edge based pulses based on the first power supply level to edge based pulses based on a second power supply level; and a divider circuit, coupled with the voltage level shifter, operable to generate an output signal from the edge based pulses based on the second power supply level.

Abstract: A cross-coupled inverter includes a first inverter and a second inverter cross-coupled such that the input terminal of each inverter is connected to the output terminal of the other inverter. A set signal is input to the gate of a first set transistor, and an inverted set signal is input to the gate of a fourth set transistor. A reset signal R is input to the gate of a first reset transistor of a reset unit, and an inverted reset signal is input to the gate of a fourth reset transistor thereof. The gate of the second set transistor and the gate of the third reset transistor are connected to the output terminal of the second inverter. The gate of the third set transistor and the gate of the second reset transistor are connected to the output terminal of the first inverter.

Abstract: An integrated circuit comprises a processor, a controller and plural terminals. Each terminal constitutes a connection between the integrated circuit and a peripheral device. Each terminal is connected to a logic circuit on the integrated circuit by a respective IO cell in series connection with a respective IO isolation circuit and wherein the controller is operable on power up of the integrated circuit to activate a reset state and to release the reset state prior to releasing IO isolation by one or more of the IO isolation circuits. Each IO isolation circuit may be arranged so that a default state of the IO isolation circuit is a state in which the IO cell is isolated from the logic circuit. The IO isolation circuits may be controllable by software, for instance a driver for a peripheral device connected to the terminal associated with the IO isolation circuit. Plural IO isolation circuits may be connected so as to be commonly controllable by a single control signal from the controller.

Abstract: A circuit arrangement for shifting a voltage level comprises a data-current converter (2) that is connected to a first connection (K1) and that has an input for feeding a digital input data signal (DIN), a first output for providing a current (I), and also a second output for providing a reference current (I1), and a current-data converter (3) that is connected to a second connection (K2) and that has a first input for feeding the current (I), a second input for feeding the reference current (I1), and also an output for providing a digital output data signal (DOUT). Here, a voltage level of the digital output data signal (DOUT) is different from a voltage level of the digital input data signal (DIN). In addition, a method for shifting a voltage level is provided.

Abstract: A digital level shifter is disclosed that receives an input voltage from a first voltage domain, and provides an output voltage to a second voltage domain. The level shifter includes transistors configured in parallel with input transistors of the level shifter in order to place the output of the level shifter in a determinate state when one of the voltage domains is placed in a low power state. Further, the level shifter includes output transistors configured to equalize a rise time slew rate and fall time slew rate, improving the reliability of the level shifter as the voltage in each voltage domain varies.

Abstract: A digital level shifter is disclosed that receives an input voltage from a first voltage domain, and provides an output voltage to a second voltage domain. The level shifter includes transistors configured in parallel with input transistors of the level shifter in order to place the output of the level shifter in a determinate state when one of the voltage domains is placed in a low power state. Further, the level shifter includes output transistors configured to equalize a rise time slew rate and fall time slew rate, improving the reliability of the level shifter as the voltage in each voltage domain varies.

Abstract: A bidirectional buffer circuit includes a first terminal, a second terminal, a first output buffer to which a signal from the first terminal is input and which outputs the signal to the second terminal, a first one-shot buffer control circuit outputting a first control signal according to an earlier arriving signal out of a signal from the first terminal and a signal from the second terminal, a first one-shot buffer temporarily driving the second terminal by the first control signal, a second output buffer to which a signal from the second terminal is input and which outputs the signal to the first terminal, a second one-shot buffer control circuit outputting a second control signal according to an earlier arriving signal out of a signal from the first terminal and a signal from the second terminal, and a second one-shot buffer temporarily driving the first terminal by the second control signal.

Abstract: A level shifter includes a first level shift circuit that converts a signal level of a first pulse signal into an amplitude level of a power supply voltage, and a second level shift circuit that converts a signal level of the second pulse signal into an amplitude level. Each of the first and second level shift circuits includes a first conductivity type transistor having its gate receiving the first and second pulse signals respectively, its source connected to a ground, and its drain outputs a level shifted pulse signal, and a first transistor of a second conductivity type having its gate connected to the gate of the transistor of the first conductivity type, its drain connected to the drain of the transistor of the first conductivity type, and its source connected to the power supply via a connected transistor group, and the connected transistor group includes at least one of the second conductivity type transistors.