Apparatus and method for high voltage I/O electro-static discharge protection
An electronics chip includes a charge pump and at least one high voltage (HV) electro-static discharge (ESD) module. The charge pump is configured to provide a predetermined voltage across a microphone. The devices described herein are implemented in a standard low voltage CMOS process and has a circuit topology that provides an inherent ESD protection level (when it is powered down), which is higher than the operational (predetermined) DC level. At least one high voltage (HV) electro-static discharge (ESD) module is coupled to the output of the charge pump. The HV ESD module is configured to provide ESD protection for the charge pump and a microelectromechanical system (MEMS) microphone that is coupled to the chip. The at least one HV ESD module includes a plurality of PMOS or NMOS transistors having at least one high voltage NWELL/DNWELL region formed within selected ones of the PMOS or NMOS transistors. The at least one high voltage NWELL/DNWELL region has a breakdown voltage sufficient to allow a low voltage process to be used to construct the chip and still allow the HV ESD module to provide ESD protection for the chip.
1. An electronics chip, the chip comprising:
a charge pump, the charge pump configured to provide a predetermined voltage across a microphone, the charge pump being implemented in a low voltage CMOS process;
at least one high voltage (HV) electro-static discharge (ESD) module coupled to the output of the charge pump, the HV ESD module configured to provide ESD protection for the charge pump and a microelectromechanical system (MEMS) microphone that is coupled to the chip;
wherein the at least one HV ESD module includes a plurality of PMOS or NMOS transistors wherein selected ones of the PMOS or NMOS transistors include a first PWELL region, a high voltage NWELL region, and a second PWELL region, and the first PWELL region is separated from the high voltage NWELL region by a distance L that completely separates the first PWELL region from the high voltage NWELL region, the distance L being effective increase the breakdown voltage of a NWELL to substrate junction and to allow a low voltage process to be used to construct the chip and still allow the HV ESD module to provide ESD protection for the chip;
a filter;
wherein the at least one high voltage (HV) electro-static discharge (ESD) module is coupled between the charge pump and the filter, and wherein the output of the filter is coupled to a microphone transducer.
2. The chip of claim 1 wherein a high voltage terminal is formed at a drain terminal of a selected one of the plurality of NMOS transistors to form an LDMOS transistor, the high voltage terminal is effective to increase a drain to source breakdown voltage of the selected transistor.
3. The chip of claim 1 wherein the microphone comprises a diaphragm and a back plate.
4. The chip of claim 1 , wherein the filter comprises at least one diode to provided discharge protection for the filter.
5. The chip of claim 1 , wherein the filter comprises at least one diode and at least one active device.
6. An electronics chip, the chip comprising:
a charge pump, the charge pump configured to provide a predetermined voltage across a microphone, the charge pump being implemented in a low voltage CMOS process;
at least one high voltage (HV) electro-static discharge (ESD) module coupled to the output of the charge pump, the HV ESD module configured to provide ESD protection for the charge pump and a microelectromechanical system (MEMS) microphone that is coupled to the chip;
wherein the at least one HV ESD module includes a plurality of PMOS or NMOS transistors having at least one high voltage NWELL/DNWELL region formed within selected ones of the PMOS or NMOS transistors, the at least one high voltage NWELL/DNWELL region having a breakdown voltage sufficient to allow a low voltage process to be used to construct the chip and still allow the HV ESD module to provide ESD protection for the chip;
a filter;
wherein the at least one high voltage (HV) electro-static discharge (ESD) module is coupled between the charge pump and the filter, and wherein the output of the filter is coupled to a microphone transducer.
7. The chip of claim 6 wherein a high voltage terminal is formed at a drain terminal of a selected one of the plurality of NMOS transistors to form an LDMOS transistor, the high voltage terminal is effective to increase a drain to source breakdown voltage of the selected transistor.
8. The chip of claim 6 wherein the microphone comprises a diaphragm and a back plate.
9. The chip of claim 6 , wherein the filter comprises at least one diode to provided discharge protection for the filter.
10. The chip of claim 6 , wherein the filter comprises at least one diode and at least one active device.