Abstract: A switch circuit is provided. The switch circuit includes a P-type transistor switch and a first P-type control transistor. The P-type transistor switch includes a first control end, a first output end, and a first input end. The first input end receives a first input signal whose logic level is one. The first P-type control transistor is coupled to the first input end and the first control end. The first P-type control transistor includes a second control end. The second control end receives a second input signal whose logic level is zero to turn on the first P-type control transistor. When the first P-type control transistor is turned on, the first input signal is transmitted to the first control end of the P-type transistor switch to turn off the P-type transistor switch.

Abstract: The present invention discloses a voltage level conversion circuit. A first and a second N-type driving transistors turn on when a first power voltage source supplies a high state voltage. A voltage transmission circuit transmits a first and a second input voltages having opposite levels to sources of the first and the second N-type driving transistors. A current source operates according to a second supply voltage source and has a first and a second output terminals. A first and a second connection transistors respectively couple between the drain of the first N-type driving transistor and the second output terminal and between the drain of the second N-type driving transistor and the first output terminal. The first and the second connection transistors turn on and off when the first voltage supply source supplies the high state voltage and a low state voltage.

Abstract: A switch circuit is provided. The switch circuit includes a P-type transistor switch and a first P-type control transistor. The P-type transistor switch includes a first control end, a first output end, and a first input end. The first input end receives a first input signal whose logic level is one. The first P-type control transistor is coupled to the first input end and the first control end. The first P-type control transistor includes a second control end. The second control end receives a second input signal whose logic level is zero to turn on the first P-type control transistor. When the first P-type control transistor is turned on, the first input signal is transmitted to the first control end of the P-type transistor switch to turn off the P-type transistor switch.

Abstract: The present invention discloses a voltage level conversion circuit. A first and a second N-type driving transistors turn on when a first power voltage source supplies a high state voltage. A voltage transmission circuit transmits a first and a second input voltages having opposite levels to sources of the first and the second N-type driving transistors. A current source operates according to a second supply voltage source and has a first and a second output terminals. A first and a second connection transistors respectively couple between the drain of the first N-type driving transistor and the second output terminal and between the drain of the second N-type driving transistor and the first output terminal. The first and the second connection transistors turn on and off when the first voltage supply source supplies the high state voltage and a low state voltage.

Abstract: The present invention discloses a circuit capable of protecting low-voltage devices. The circuit includes: a pin configured to receive a signal of an external device; a control voltage generating circuit configured to generate a first control voltage according to a supply voltage to turn on a protected device when the supply voltage is at a high level, and generate a second control voltage according to a voltage of the pin to turn on the protected device when the supply voltage is at a low level; and the protected device configured to be turned on according to one of the first and the second control voltages and thereby electrically couple the pin with an internal circuit, in which the difference between the voltage of the pin and each of the first and the second control voltages is within a maximum withstanding voltage of the protected device.

Abstract: The present invention discloses a circuit capable of protecting low-voltage devices. The circuit includes: a pin configured to receive a signal of an external device; a control voltage generating circuit configured to generate a first control voltage according to a supply voltage to turn on a protected device when the supply voltage is at a high level, and generate a second control voltage according to a voltage of the pin to turn on the protected device when the supply voltage is at a low level; and the protected device configured to be turned on according to one of the first and the second control voltages and thereby electrically couple the pin with an internal circuit, in which the difference between the voltage of the pin and each of the first and the second control voltages is within a maximum withstanding voltage of the protected device.

Abstract: A switch and a multiplexer including the same are provided, which are applicable to selectively transmit the high frequency signal from an input terminal to an output terminal therethrough. The switch includes a switch device and a variable resistor. The switch device is connected between the input terminal and the output terminal, and the switch device includes a control terminal and is configured to be switched between ON and OFF according to a switch controlling signal provided to the control terminal. The variable resistor is connected to the control terminal and configured to change to a first resistance while the switch device is ON, and to change to a second resistance while the switch device is OFF according to a resistor controlling signal. The first resistance is higher than the second resistance, and the resistor controlling signal is changed corresponding to the switch controlling signal.

Abstract: A switch and a multiplexer including the same are provided, which are applicable to selectively transmit the high frequency signal from an input terminal to an output terminal therethrough. The switch includes a switch device and a variable resistor. The switch device is connected between the input terminal and the output terminal, and the switch device includes a control terminal and is configured to be switched between ON and OFF according to a switch controlling signal provided to the control terminal. The variable resistor is connected to the control terminal and configured to change to a first resistance while the switch device is ON, and to change to a second resistance while the switch device is OFF according to a resistor controlling signal. The first resistance is higher than the second resistance, and the resistor controlling signal is changed corresponding to the switch controlling signal.