Switch off state isolation

1 . An apparatus comprising:

a switch assembly having first and second switch terminals and a control terminal, the switch assembly including a circuit, and the switch assembly configurable to:

responsive to the control terminal having a first state: connect the first switch terminal to the second switch terminal, and disconnect a terminal of the circuit from the first switch terminal, to enable a transmission of a signal between the first and second switch terminals; and

responsive to the control terminal having a second state: connect the terminal of the circuit to the first switch terminal, and disconnect the first switch terminal from the second switch terminal, to disable the transmission of the signal between the first and second switch terminals.

2 . The apparatus of claim 1 , wherein the circuit terminal is a first circuit terminal, the leakage attenuation circuit has a second circuit terminal coupled to the second switch terminal, and the leakage attenuation circuit is configured to:

provide a second signal based on the first signal at the second or first circuit switch terminal to combine with a leakage signal that propagates between the first and second switch terminals when the control terminal has the second state to attenuate the leakage signal.

3 . The apparatus of claim 2 , wherein the circuit includes at least one of an impedance inverter circuit or a phase shifter circuit.

4 . The apparatus of claim 2 , wherein the circuit is configurable to generate the first signal having a 180 degree phase shift relative to the second signal.

5 . The apparatus of claim 2 , wherein the circuit is configurable to generate the second signal by attenuating the first signal.

6 . The apparatus of claim 2 , wherein the circuit includes a capacitor coupled between the first and second circuit switch terminals.

7 . The apparatus of claim 6 , wherein the capacitor has a configurable capacitance.

8 . The apparatus of claim 7 , wherein a frequency of the leakage signal to be attenuated by the circuit is configurable based on the configurable capacitance of the capacitor.

9 . The apparatus of claim 6 , wherein the capacitor includes a microelectromechanical system (MEMS) capacitor.

10 . The apparatus of claim 1 , wherein the circuit includes a metal strip.

11 . The apparatus of claim 1 , wherein the circuit includes an inductor and a capacitor.

12 . The apparatus of claim 1 , wherein the switch assembly includes a single pole double throw switch.

13 . The apparatus of claim 1 , wherein the switch assembly includes:

a first switch coupled between the first switch terminal and the second switch terminal, the first switch having a first switch control terminal coupled to the control terminal; and

a second switch coupled between the first switch terminal and the terminal of the circuit, the second switch having a second switch control terminal coupled to the control terminal.

14 . The apparatus of claim 13 , wherein the first switch includes a first microelectromechanical system (MEMS) switch, and the second switch includes a second MEMS switch.

15 . The apparatus of claim 13 , wherein each of the first and second switches includes a respective transistor.

16 . A system comprising:

a controller having first and second control outputs, the controller configurable to:

in a first mode, set the first control output to a first state and the second control output to a second state; and

in a second mode, set the first control output to the second state and the second control output to the first state;

a first switch assembly coupled between a first radio frequency (RF) terminal and a second RF terminal, the first switch assembly having a first switch control terminal coupled to the first control output and including a first circuit, the first switch assembly configurable to:

responsive to the first switch control terminal having the first state, connect the first RF terminal to the second RF terminal and disconnect a first circuit terminal of the first circuit from one of the first RF terminal or the second RF terminal; and

responsive to the first switch control terminal having the second state, connect the first circuit terminal to the one of the first RF terminal or the second RF terminal and disconnect the first RF terminal from the second RF terminal; and

a second switch assembly coupled between a third RF terminal and the second RF terminal, the second switch assembly having a second switch control terminal coupled to the second control output and including a second circuit, the second switch assembly configurable to:

responsive to the second switch control terminal having the second state, connect the third RF terminal to the second RF terminal and disconnect a second circuit terminal of the second circuit from one of the third RF terminal or the second RF terminal; and

responsive to the second switch control terminal having the first state, connect the second circuit terminal to the one of the third RF terminal or the second RF terminal and disconnect the third RF terminal from the second RF terminal.

17 . The system of claim 16 , wherein:

the first circuit has a third circuit terminal and is configurable to:

receive a first signal at the first or third circuit terminal; and

provide the first signal responsive to a second signal at the third or first circuit terminal to combine with a first leakage signal that propagates between the first RF terminal and the second RF terminal when the first switch control terminal has the second state; and

the second circuit has a fourth circuit terminal and is configurable to:

provide a third signal responsive to a fourth signal at the fourth or second circuit terminal to combine with a second leakage signal that propagates between the third RF terminal and the second RF terminal when the second switch control terminal has the first state.

18 . The system of claim 16 , wherein at least one of the first or second circuit includes at least one of an impedance inverter circuit or a phase shifter circuit.

19 . The system of claim 16 , wherein at least one of the first or second circuit includes at least one of: a metal strip, an inductor, or a capacitor.

20 . The system of claim 16 , wherein the first switch assembly includes a first MEMS switch or a first transistor coupled between the first RF terminal and the second RF terminal, and a second MEMS switch or a second transistor coupled between the first circuit terminal and the one of the first RF terminal or the second RF terminal; and

wherein the second switch assembly includes a third MEMS switch or a third transistor coupled between the third RF terminal and the second RF terminal, and a fourth MEMS switch or a fourth transistor coupled between the second circuit terminal and the one of the third RF terminal or the second RF terminal.

21 . The system of claim 16 , further comprising a first antenna, a second antenna, and an RF choke, wherein the first antenna is coupled to the second RF terminal, the second antenna is coupled to the third RF terminal, and the RF choke is coupled to the first RF terminal.

22 . The system of claim 16 , wherein the first switch assembly, the second switch assembly, the first circuit, the second circuit, and the controller are part of an integrated circuit.

23 . A method comprising:

generating a first signal as a phase-shifted and attenuated version of a second signal at a first switch terminal of a switch assembly;

responsive to the switch assembly being in an on state:

transmitting the second signal to a second switch terminal; and

responsive to the switch assembly being in an off state:

transmitting the first signal to the second switch terminal to disable the transmission of the second signal between the first and second switch terminals.

24 . The method of claim 23 , wherein generating the first signal as the phase-shifted and attenuated version of the second signal includes phase shifting the second signal by 180 degrees.

25 . The method of claim 23 , wherein:

connecting the first switch terminal to the second switch terminal includes enabling a first MEMS switch or a first transistor, and transmitting the second signal to the second switch terminal includes transmitting the second signal to the second switch terminal through the enabled first MEMS switch or the enabled first transistor; and

disconnecting the first switch terminal from the second switch terminal includes disabling the first MEMS switch or the first transistor, and transmitting the first signal to the second switch terminal includes transmitting the first signal to the second switch terminal through a second MEMS switch or a second transistor.

26 . An apparatus comprising:

a switch assembly having first and second switch terminals and a control terminal, the switch assembly including a circuit having a property based on a leakage characteristic between the first and second switch terminals, and the switch assembly configurable to:

responsive to the control terminal having a first state to enable the switch assembly:

connect the first switch terminal to the second switch terminal, and disconnect a terminal of the circuit from the first switch terminal; and

responsive to the control terminal having a second state to disable the switch assembly:

connect the terminal of the circuit to the first switch terminal, and disconnect the first switch terminal from the second switch terminal.

27 . The apparatus of claim 26 , wherein the circuit is configurable to attenuate a leakage signal at the first or second switch terminal when the control terminal is in the second state.