Radio frequency switch circuit and control method thereof

1. A radio frequency switch circuit, comprising:

a first switch circuit unit connected between a signal port and an antenna port;

a second switch circuit unit connected between the signal port and a ground; and

a third switch circuit unit connected between the antenna port and the ground,

wherein the first switch circuit unit, the second switch circuit unit, and the third switch circuit unit each comprise a transistor, and

an operation reference voltage defining a gate-to-source voltage of the transistor in the third switch circuit unit is lower than an operation reference voltage defining a gate-to-source voltage of the transistor in the first switch circuit unit.

2. The radio frequency switch circuit of claim 1 , further comprising:

a control unit configured to generate a first gate signal, a second gate signal, and a third gate signal to control the first switch circuit unit, the second switch circuit unit, and the third switch circuit unit, respectively.

3. The radio frequency switch circuit of claim 2 , wherein the control unit excludes generation of the first gate signal, the second gate signal, and the third gate signal in a low power mode.

4. The radio frequency switch circuit of claim 3 , wherein the first switch circuit unit enters an off-state in response to the first gate signal not being generated,

the second switch circuit unit enters the off-state in response to the second gate signal not being generated, and

the third switch circuit unit enters an on-state in response to the third gate signal not being generated.

5. The radio frequency switch circuit of claim 1 , wherein the first switch circuit unit enters an on-state in a transmission and reception mode and enters an off-state in an isolation mode, and

the second switch circuit unit enters the off-state in the transmission and reception mode and enters the on-state in the isolation mode.

6. The radio frequency switch circuit of claim 1 , wherein the transistor of the third switch circuit unit is a depletion-type field effect transistor, and

the operation reference voltage of the transistor of the third switch circuit is a negative voltage.

7. The radio frequency switch circuit of claim 1 , wherein the first switch circuit unit, the second switch circuit unit, and the third switch circuit unit each comprise transistors, and

one terminal of each of the transistors receives a gate signal.

8. The radio frequency switch circuit of claim 7 , wherein the transistors enter an on-state when a voltage of the gate signal is higher than the operation reference voltage associated with the first switch circuit unit, the second switch circuit unit, and the third switch circuit unit.

9. The radio frequency switch circuit of claim 6 , wherein the depletion-type field effect transistor has a gate terminal connected to a pull down resistor connected to the ground.

10. The radio frequency switch circuit of claim 1 , wherein the transistor of the first switch circuit unit is a field effect transistor of an enhancement type, and the transistor of the of the third switch circuit unit is a depletion type field effect transistor with a negative operation reference voltage.

11. A radio frequency switch circuit, comprising:

a first switch circuit unit connected between a first signal port and an antenna port;

a second switch circuit unit connected between the first signal port and a ground;

a third switch circuit unit connected between the antenna port and the ground;

a fourth switch circuit unit connected between a second signal port and the antenna port; and

a fifth switch circuit unit connected between the second signal port and the ground,

wherein the first switch circuit unit, the second switch circuit unit, the third switch circuit, the fourth switch circuit unit, and the fifth switch circuit unit each comprise a transistor, and

an operation reference voltage defining a gate-to-source voltage of the transistor in the third switch circuit unit is lower than an operation reference voltage defining a gate-to-source voltage of the transistor in the first switch circuit unit and an operation reference voltage defining a gate-to-source voltage of the transistor in the fourth switch circuit unit.

12. The radio frequency switch circuit of claim 11 , further comprising:

a control unit configured to generate a first gate signal, a second gate signal, a third gate signal, a fourth gate signal, and a fifth gate signal to control the first switch circuit unit, the second switch circuit unit, the third switch circuit unit, the fourth switch circuit unit, and the fifth switch circuit unit, respectively.

13. The radio frequency switch circuit of claim 12 , wherein the third switch circuit unit enters an on-state in a low power mode, and

the control unit excludes generation of the first, the second, the third, the fourth, and the fifth gate signals in the low power mode.

14. The radio frequency switch circuit of claim 11 , wherein the second switch circuit unit enters the off-state in response to the first signal port being in the transmission and reception mode and enters the on-state in response to other signal ports being in the transmission and reception mode or the isolation mode.

15. The radio frequency switch circuit of claim 11 , wherein the transistor in the third switch circuit unit is a depletion-type field effect transistor,

the operation reference voltage is a negative voltage, and

the depletion-type field effect transistor comprises a gate terminal connected to a pull down resistor connected to the ground.

16. The radio frequency switch circuit of claim 11 , wherein the first switch circuit unit enters an on-state in response to the first signal port being in a transmission and reception mode and enters an off-state in response to other signal ports being in the transmission and reception mode or an isolation mode.

17. The radio frequency switch circuit of claim 11 , wherein the control unit interrupts conduction between signal ports and an antenna port in response to the radio frequency switch circuit being operated in a first mode,

conducts between the antenna port and a ground in response to the radio frequency switch circuit being operated in the first mode,

conducts between one of the signal ports and the antenna port and interrupts conduction between other signal ports and the antenna port in response to the radio frequency switch circuit being operated in a second mode,

interrupts conduction between one of the signal ports and the ground and conducts between other signal ports and the ground in response to the radio frequency switch circuit being operated in the second mode, and

interrupts conduction between the antenna port and the ground in response to the radio frequency switch circuit being operated in the second mode.

18. The radio frequency switch circuit of claim 17 , wherein the control unit interrupts conduction between the signal ports and the ground in response to the radio frequency switch circuit is operated in the first mode,

interrupts conduction between the signal ports and the antenna port in response to the radio frequency switch circuit being operated in a third mode,

conducts between the signal ports and the ground in response to the radio frequency switch circuit being operated in the third mode, and

interrupts the signal transmission and reception between the antenna port and the ground in response to the radio frequency switch circuit being operated in the third mode.