Active charge bleed methods for MEMS switches
Impedance paths for integrated circuits having microelectromechanical systems (MEMS) switches that allow for electrical charge to bleed from circuit nodes to fixed electric potentials (e.g., ground) are described. Such paths are referred to herein as charge bleed circuits. The circuit nodes may be circuit locations where electrical charge may accumulate because there is no other path for the electrical charge to dissipate. In some embodiments, a charge bleed circuit includes a switchable device (e.g., a MEMS switch, a solid-state device switch, or a circuit including various solid-state device switches that, collectively, implement a device that can be switched on and off) that connects and disconnects the impedance path from a circuit node. This may allow the device to perform different types of measurements at desired performance levels.
1 . A microelectromechanical systems (MEMS) device comprising:
a MEMS switch;
a circuit node electrically connected to a side of the MEMS switch;
a charge bleed circuit comprising a switchable device and a resistor in series with the switchable device, the charge bleed circuit connecting the circuit node to a fixed electric potential; and
control circuitry configured to maintain the switchable device in a non-conductive state during a time interval in which the MEMS switch is in a conductive state;
wherein the resistor is monolithically integrated with the MEMS switch.
2 . The MEMS device of claim 1 , wherein the circuit node is a first circuit node, the side of the MEMS switch is a first side, and the charge bleed circuit is a first charge bleed circuit, and the switchable device is a first switchable device, and wherein the MEMS device further comprises:
a second circuit node electrically connected to a second side of the MEMS switch; and
a second charge bleed circuit comprising a second switchable device, the second charge bleed circuit connecting the second circuit node to the fixed electric potential.
3 . The MEMS device of claim 2 , wherein the control circuitry is further configured to maintain the second switchable device in a non-conductive state during the time interval.
4 . The MEMS device of claim 1 , wherein the switchable device comprises a MEMS switch.
5 . The MEMS device of claim 1 , wherein the switchable device comprises a solid-state device switch.
6 . The MEMS device of claim 5 , wherein the solid-state device switch comprises a field effect transistor (FET) and/or a diode.
7 . The MEMS device of claim 1 , wherein:
when the switchable device is in a conductive state, the resistor couples the circuit node to the fixed electric potential, and
when the switchable device is in the non-conductive state, the circuit node is floating.
8 . The MEMS device of claim 1 , wherein the MEMS switch comprises a cantilevered MEMS switch or a teeter-totter MEMS switch.
9 . A microelectromechanical systems (MEMS) device comprising:
a MEMS switch;
a circuit node electrically connected to a side of the MEMS switch;
a resistive charge bleed circuit comprising a switchable device and a resistor monolithically integrated with the MEMS switch, the resistive charge bleed circuit connecting the circuit node to a fixed electric potential; and
control circuitry configured to maintain the switchable device coupled to the fixed electric potential when the MEMS switch is in a conductive state.
10 . The MEMS device of claim 9 , wherein the circuit node is a first circuit node, the side of the MEMS switch is a first side, and the charge bleed circuit is a first resistive charge bleed circuit, and the switchable device is a first switchable device, and wherein the MEMS device further comprises:
a second circuit node electrically connected to a second side of the MEMS switch; and
a second resistive charge bleed circuit comprising a second switchable device, the second resistive charge bleed circuit connecting the second circuit node to the fixed electric potential.
11 . The MEMS device of claim 10 , wherein the control circuitry is further configured to maintain the second switchable device coupled to the fixed electric potential when the MEMS switch is in a conductive state.
12 . The MEMS device of claim 9 , wherein the switchable device comprises a MEMS switch.
13 . The MEMS device of claim 9 , wherein the switchable device comprises a solid-state device switch.
14 . The MEMS device of claim 9 , wherein:
when the switchable device is in a conductive state, the resistive charge bleed circuit couples the circuit node to the fixed electric potential, and
when the switchable device is in a non-conductive state, the circuit node is floating.
15 . A method of operating a microelectromechanical systems (MEMS) device comprising a MEMS switch, the method comprising:
decoupling a side of the MEMS switch from a fixed electric potential by interrupting a resistive charge bleed circuit, wherein interrupting the charge bleed circuit comprises turning off a switchable device;
at a first time, turning on the MEMS switch; and
at a second time subsequent to the first time, turning off the MEMS switch,
wherein, during at least a time interval defined between the first time and the second time, the side of the MEMS switch is decoupled from the fixed electric potential; and
wherein the resistive charge bleed circuit comprises a resistor monolithically integrated with the MEMS switch.
16 . The method of claim 15 , wherein decoupling the side of the MEMS switch from the fixed electric potential occurs prior to the first time.
17 . The method of claim 15 , wherein decoupling the side of the MEMS switch from the fixed electric potential occurs at the first time.
18 . The method of claim 15 , further comprising coupling the side of the MEMS switch to the fixed electric potential by forming the resistive charge bleed circuit, wherein forming the charge bleed circuit comprises turning on the switchable device,
wherein coupling the side of the MEMS switch to the fixed electric potential occurs at, or subsequent to, the second time.