# US 9,520,251 B2 · RF switch with inter-domain ESD protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,251 B2 - Document ID: US9520251B2 - Status: Granted - Kind: B2 - Application number: 13/871,630 - Filed: 2013-04-26 - Published: 2014-10-30 - Granted: 2016-12-13 - Earliest claimed: 2013-04-26 - Assignees: Ferfics Limited - Applicants: Ferfics Limited - Inventors: John Keane; John O'Sullivan; Ian O'Regan - Web page: https://patentgrep.com/patent/US9520251B2 ## CPC - H02H 9/046: {responsive to excess voltage appearing at terminals of integrated circuits} - H01H 11/00: Apparatus or processes specially adapted for the manufacture of electric switches (processes specially adapted for manufacture of rectilinearly movable switches having a plurality of operating members associated with different sets of contacts, e.g. keyboards, H01H13/88) - H02M 3/155: using semiconductor devices only - H03K 17/693: Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors (logic circuits H03K19/00; code converters H03M5/00, H03M7/00) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract An RF switch with inter-domain ESD protection. The RF switch comprises an RF domain section having a plurality of RF switching elements; and a DC domain section having circuitry configured for driving the RF switching elements. At least one primary ESD protection element is operably coupled between the RF domain section and DC domain section. ## Claims ### Claim 1 An RF switch integrated circuit with inter-domain ESD protection; the RF switch comprising: an RF domain section having a plurality of RF switching elements; a DC domain section having circuitry configured for driving the RF switching elements; and at least one primary ESD protection element formed on a semiconductor die containing the RF domain section and the DC domain section; wherein the at least one primary ESD protection element is internally coupled on the semiconductor die between a pin of the RF domain section and a pin of the DC domain section and provides a direct discharge path for inter-domain ESD events occuring between pins associated with the DC domain section and pins associated with the RF domain section. ### Claim 2 (depends on 1) An RF switch as claimed in claim 1, wherein the at least one primary ESD protection element is internally coupled on the semiconductor die between a supply voltage pin in the DC domain section and an RF ground reference pin in the RF domain section. ### Claim 3 (depends on 2) An RF switch as claimed in claim 2, wherein the RF domain section includes one or more RF ground reference pins each associated with a corresponding transistor connecting two RF pins. ### Claim 4 (depends on 1) An RF switch as claimed in claim 1, wherein the DC domain section comprises one or more secondary ESD protection elements. ### Claim 5 (depends on 4) An RF switch as claimed in claim 4, wherein the DC domain section comprises two secondary ESD protection elements. ### Claim 6 (depends on 5) An RF switch as claimed in claim 5, wherein one of the secondary ESD protection elements is operably coupled to an output node of a voltage regulator in the DC domain section. ### Claim 7 (depends on 6) An RF switch as claimed in claim 6, wherein the other one of the secondary ESD protection elements is operably coupled to an output node of a negative voltage generator in the DC domain section. ### Claim 8 (depends on 1) An RF switch as claimed in claim 1, further comprising a plurality of RF isolation filters operably coupled between the DC domain section and the RF domain section, the respective RF isolation filters include resistive loads which are scaled relatively to an effective resistive load that occurs between an output node of the RF isolation filter and a terminal of an RF switch element. ### Claim 9 (depends on 1) An RF switch as claimed in claim 1, further comprising at least one RF isolation filter having an ESD protection element, the at least one RF isolation filter being operably coupled between the DC domain section and the RF domain section. ### Claim 10 (depends on 9) An RF switch as claimed in claim 9, wherein the at least one RF isolation filter comprises a pair of capacitors and a resistor operably coupled there between, one of the capacitors is associated with the DC domain section and the other capacitor is associated with the RF domain section, the ESD protection element is operably coupled to the resistor. ### Claim 11 (depends on 1) An RF switch as claimed in claim 1, wherein the RF domain section comprises at least one stack of transistors, and a clamping element is associated with each transistor. ### Claim 12 (depends on 11) An RF switch as claimed in claim 11, wherein the clamping element is operably coupled between a body terminal and a gate terminal of the corresponding transistor. ### Claim 13 (depends on 12) An RF switch as claimed in claim 12, wherein the clamping element comprises a transistor. ### Claim 14 (depends on 13) An RF switch as claimed in claim 13, wherein the clamping element comprises a MOSFET transistor. ### Claim 15 (depends on 12) An RF switch as claimed in claim 12, wherein the clamping element is turned off during normal operation of the RF switch and is turned on in response to experiencing an ESD event. ### Claim 16 A semiconductor die having an RF switch integrated circuit with inter-domain ESD protection fabricated thereon, wherein the RF switch integrated circuit comprises: an RF domain section having a plurality of RF switching elements; a DC domain section having circuitry configured for driving the RF switching elements; and at least one primary ESD element formed on a semiconductor die containing the RF domain section and the DC domain section; wherein the at least one primary ESD protection element is internally coupled on the semiconductor die between a pin of the RF domain section and a pin of the DC domain section and provides a direct discharge path for inter-domain ESD events occuring between pins associated with the DC domain section and pins associated with the RF domain section. ### Claim 17 (depends on 16) A semiconductor substrate as claimed in claim 16 comprising a silicon-on-insulator arrangement. ### Claim 18 A method of fabricating an RF switch integrated circuit having inter-domain ESD protection; the method comprises: providing an RF domain section having a plurality of RF switching elements on a semiconductor die; providing a DC domain section having circuitry configured for driving the RF switching elements on the semiconductor die; and forming at least one primary ESD protection element on the semiconductor die containing the RF domain section and the DC domain section; wherein the at least one primary ESD protection element is internally coupled between a pin of the RF domain section and a pin of the DC domain and provides a direct discharge path for inter-domain ESD events occuring between pins associated with the DC domain section and pins associated with the RF domain section. ### Claim 19 (depends on 18) A method as claimed in claim 18, wherein the at least one primary ESD protection element is operably coupled between a supply voltage pin in the DC domain section and an RF ground reference pin in the RF domain section. ### Claim 20 (depends on 18) A method as claimed in claim 18, further comprising: providing one or more secondary ESD protection elements in the DC domain section. ### Claim 21 (depends on 20) A method as claimed in claim 20, further comprising: coupling one of the secondary ESD protection elements to an output node of a voltage regulator in the DC domain section. ### Claim 22 (depends on 21) A method as claimed in claim 21, further comprising: coupling a further secondary ESD protection elements to an output node of a negative voltage generator in the DC domain section. ### Claim 23 (depends on 18) A method as claimed in claim 18, further comprising coupling a plurality of RF isolation filters between the DC domain section and the RF domain section, the respective RF isolation filters include resistive loads which are scaled relatively to an effective resistive load that occurs between an output node of the RF isolation filter and a terminal of an RF switch element. ### Claim 24 (depends on 18) A method as claimed in claim 18, further comprising: providing at least one RF isolation filter having an ESD protection element between the DC domain section and the RF domain section. ### Claim 25 (depends on 24) A method as claimed in claim 24, wherein the at least one RF isolation filter comprises a pair of capacitors and a resistor operably coupled there between, one of the capacitors is associated with the DC domain section and the other capacitor is associated with the RF domain section, the ESD protection element is operably coupled to the resistor. ### Claim 26 (depends on 18) A method as claimed in claim 18, further comprising: providing at least one stack of transistors in the RF domain section, and providing respective clamping elements on the semiconductor substrate which are associated with corresponding transistors. ### Claim 27 (depends on 26) A method as claimed in claim 26, further comprising: coupling the respective clamping element between a body terminal and a gate terminal of the corresponding transistors.