Switch circuit
View Patent ↗Provided is a switch circuit capable of reliably controlling the transmission or interruption of a voltage of from GND to VDD to an internal circuit even when a positive or negative voltage is input to an input terminal. By adding PMOS transistors to NMOS transistors constituting the switch circuit and controlling gates of the PMOS transistors by a voltage of the input terminal, the transmission or interruption of the voltage of from GND to VDD can be reliably controlled.
1. A switch circuit for routing one of a positive voltage and a negative voltage from and input terminal to an output terminal, the switch circuit comprising:
a first NMOS transistor including a drain connected to the input terminal, a source connected to a first node, and a gate connected to a control terminal;
a second NMOS transistor including a drain connected to the first node, a source connected to a second node, and a gate connected to the control terminal;
a first PMOS transistor including a source connected to the input terminal, a drain connected to the first node;
a second PMOS transistor including a source connected to the first node, a drain connected to the second node, and a gate connected to the control terminal via the inverter;
a third NMOS transistor including a source connected to a ground voltage, a drain connected to the first node, and a gate connected to the control terminal via the inverter; and
a level shift circuit that includes an input terminal connected to the control terminal, an output terminal connected to a gate of the first PMOS transistor, and a power supply terminal connected to the input terminal,
wherein the first PMOS transistor includes a back gate connected to the input terminal of the switch circuit.