# US 7,741,896 B2 · High voltage drive circuit employing capacitive signal coupling and associated devices and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,741,896 B2 - Document ID: US7741896B2 - Status: Granted - Kind: B2 - Application number: 12/163,275 - Filed: 2008-06-27 - Published: 2009-08-20 - Granted: 2010-06-22 - Earliest claimed: 2008-02-15 - Assignees: Avago Technologies ECBU IP (Singapore) Pte. Ltd. - Inventors: Fun Kok Chow; Gek Yong Ng; Richard Kok Keong Lum - Web page: https://patentgrep.com/patent/US7741896B2 ## CPC - H04L 25/0266: {Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling} - H10D 1/68: Capacitors having no potential barriers - H10D 1/692: {Electrodes} - H10W 20/496: {Capacitor integral with wiring layers} - H10W 44/601: {Capacitive arrangements (H10W44/20 takes precedence)} - H10W 72/00: Interconnections or connectors in packages - H10W 90/293: {characterised by non-galvanic coupling between the chips, e.g. capacitive coupling} - H10D 89/60: Integrated devices comprising arrangements for electrical or thermal protection, e.g. protection circuits against electrostatic discharge [ESD] - H10W 72/5445: {being orthogonal to a side surface of the chip, e.g. parallel arrangements} - H10W 90/753: {between laterally-adjacent chips} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract According to one embodiment, there is provided a high voltage drive circuit comprising drive and sense electrodes formed substantially in a single plane. The device effects signal transfer between drive and receive circuits through the drive and sense electrodes by capacitive means, and permits high voltage devices, such as IGBTs, to be driven thereby without the use of high voltage transistors, thereby eliminating the need to use expensive fabrication processes such as SOI when manufacturing high voltage gate drive circuits and ICs. The device may be formed in a small package using, by way of example, using CMOS or other conventional low-cost semiconductor fabrication and packaging processes. ## Claims ### Claim 1 A high voltage drive circuit, comprising: at least one drive electrode comprising a drive input connected to a low voltage portion of the circuit, the drive electrode being formed of a first electrically conductive metal, metal alloy or metal mixture; at least one sense electrode comprising a sense output connected to a high voltage portion of the circuit, the sense electrode being formed of a second electrically conductive metal, metal alloy or metal mixture; an electrically conductive ground plane substrate spaced apart from the drive and sense electrodes by an electrically insulative layer; a drive circuit forming a portion of the low voltage portion and configured to receive an input signal provided to the high voltage drive circuit, the drive circuit being operably coupled to the drive input and configured to transmit a drive signal based on the input signal therethrough, and a receive circuit forming a portion of the high voltage portion and operably coupled to the sense output, the receiver circuit being configured to receive the drive signal transmitted between the sense and drive electrodes and to provide at least one gate drive output signal having power and amplitude sufficient to drive an insulated-gate bipolar transistor (IGBT); wherein the drive and sense electrodes are substantially disposed in a single plane and are operably configured and associated in respect of one another to effect the transfer of drive signals therebetween by capacitive means, the gate drive circuit is a non-silicon-on-insulator CMOS integrated circuit, and high voltage isolation between the low and high voltage portions of the circuit is provided by the drive and sense electrodes. ### Claim 2 (depends on 1) The high voltage drive circuit of claim 1, wherein the low voltage portion further comprises a glitch filter configured to filter the input signal. ### Claim 3 (depends on 1) The high voltage drive circuit of claim 1, wherein the low voltage portion further comprises an oscillator circuit configured to provide an output oscillator signal. ### Claim 4 (depends on 1) The high voltage drive circuit of claim 1, wherein the at least one drive electrode and the at least one sense electrode comprise a plurality of pairs of drive and sense electrodes forming a plurality of driver channels. ### Claim 5 (depends on 1) The high voltage drive circuit of claim 1, wherein the at least one drive electrode and the at least one sense electrode comprise first and second pairs of drive and sense electrodes forming first and second driver channels. ### Claim 6 (depends on 1) The high voltage drive circuit of claim 1, wherein the receive circuit further comprises an output gate driver stage. ### Claim 7 (depends on 1) The high voltage drive circuit of claim 1, further comprising a bootstrap supply circuit. ### Claim 8 (depends on 1) The high voltage drive circuit of claim 1, wherein a first breakdown voltage between the at least one drive electrode and the at least one sense electrode exceeds about 2,000 volts RMS when applied over a time period of about one minute. ### Claim 9 (depends on 1) The high voltage drive circuit of claim 1, wherein an inter-electrode spacing Td between the drive electrode and the sense electrode is at least about 1.5 times greater than a thickness d of the electrically insulative layer. ### Claim 10 (depends on 1) The high voltage drive circuit of claim 1, wherein the first and second metals, metal alloys or metal combinations comprise one or more of gold, silver, copper, tungsten, tin, aluminium, and aluminium-copper. ### Claim 11 (depends on 1) The high voltage drive circuit of claim 1, wherein the electrically insulative layer comprises one or more of a semiconductor dielectric material, silicon oxide, silicon nitride and thick oxide. ### Claim 12 (depends on 1) The high voltage drive circuit of claim 1, wherein the electrically conductive ground plane substrate is formed of a semiconductor dielectric material or silicon. ### Claim 13 (depends on 1) The high voltage drive circuit of claim 1, wherein the drive and sense electrodes, the electrically insulative layer, and the ground plane substrate are fabricated using one or more of a CMOS process, a Bipolar-CMOS process, and a combined Bipolar-CMOS-DMOS (BCD) process. ### Claim 14 (depends on 1) The high voltage drive circuit of claim 1, wherein the circuit is encapsulated at least partially in polyimide or plastic. ### Claim 15 (depends on 1) The high voltage drive circuit of claim 1, wherein the drive and receive circuits are incorporated into an integrated circuit. ### Claim 16 (depends on 1) The high voltage drive circuit of claim 1, wherein the receive circuit further comprises a common mode rejection (CMR) circuit. ### Claim 17 (depends on 1) The high voltage drive circuit of claim 1, wherein the device is configured to transfer data between the drive and receive circuits at a rate of up to about 300 Megabits per second. ### Claim 18 (depends on 3) The high voltage drive circuit of claim 3, further comprising a charge pump circuit configured to voltage multiply the output oscillator signal thereby to amplify the drive signal. ### Claim 19 (depends on 5) The high voltage drive circuit of claim 5, wherein the low voltage portion further comprises a pair of logic driver circuits configured to drive the first and second pairs of sense and drive electrodes. ### Claim 20 (depends on 5) The high voltage drive circuit of claim 5, wherein the high voltage portion further comprises first and second rectifiers configured to receive, respectively, first and second sense electrode outputs provided by the first and second pairs of electrodes. ### Claim 21 (depends on 8) The high voltage drive circuit of claim 8, wherein the first breakdown voltage exceeds about 2,500 volts RMS when applied over a time period of about one minute. ### Claim 22 (depends on 8) The high voltage drive circuit of claim 8, wherein the first breakdown voltage exceeds about 3,000 volts RMS when applied over a time period of about one minute. ### Claim 23 (depends on 8) The high voltage drive circuit of claim 8, wherein the first breakdown voltage is greater than or equal to a second breakdown voltage between the drive electrode and the ground plane substrate. ### Claim 24 (depends on 19) The high voltage drive circuit of claim 19, wherein the logic driver circuits are complementary and are further configured to drive the first and second pairs of electrodes alternately. ### Claim 25 (depends on 20) The high voltage drive circuit of claim 20, wherein at least one of the first and second rectifiers comprises at least one MOSFET source follower. ### Claim 26 (depends on 20) The high voltage drive circuit of claim 20, further comprising first and second comparators operably connected to the first and second rectifiers and to receive first and second rectifier outputs therefrom, respectively. ### Claim 27 (depends on 24) The high voltage drive circuit of claim 24, wherein the alternately driven and complementary logic driver circuits are configured to increase common mode rejection between the first and second driver channels. ### Claim 28 (depends on 25) The high voltage drive circuit of claim 25, further comprising a low pass filter configured to filter an output signal provided by the at least one MOSFET source follower and remove or reduce ripple present therein. ### Claim 29 (depends on 26) The high voltage drive circuit of claim 26, wherein the first and second comparators each comprise means for comparing the oscillator output signal to a reference voltage. ### Claim 30 (depends on 26) The high voltage drive circuit of claim 26, further comprising an RS latch configured to receive first and second comparator outputs from the first and second comparators, respectively. ### Claim 31 (depends on 29) The high voltage drive circuit of claim 29, wherein output states provided by the first and second comparators are configured to toggle or not to toggle on the basis of the comparison between the oscillator output signal and the reference voltage. ### Claim 32 (depends on 29) The high voltage drive circuit of claim 29, wherein the electrically insulative material comprises one or more of a semiconductor dielectric material, silicon oxide, silicon nitride and thick oxide. ### Claim 33 (depends on 30) The high voltage drive circuit of claim 30, wherein outputs of the first and second comparators drive set and reset inputs of the RS latch. ### Claim 34 A method of making a high voltage drive circuit, comprising: providing at least one drive electrode comprising a drive input connected to a low voltage portion of the circuit, the drive electrode being formed of a first electrically conductive metal, metal alloy or metal mixture; providing at least one sense electrode comprising a sense output connected to a high voltage portion of the circuit, the sense electrode being formed of a second electrically conductive metal, metal alloy or metal mixture; providing an electrically conductive ground plane substrate spaced apart from the drive and sense electrodes by an electrically insulative layer; providing a drive circuit forming a portion of the low voltage portion and configured to receive an input signal provided to the high voltage drive circuit, the drive circuit being operably coupled to the drive input and configured to transmit a drive signal based on the input signal therethrough, and providing a receive circuit forming a portion of the high voltage portion and operably coupled to the sense output, the receiver circuit being configured to receive the drive signal transmitted between the sense and drive electrodes and to provide at least one gate drive output signal having power and amplitude sufficient to drive an insulated-gate bipolar transistor (IGBT); wherein the drive and sense electrodes are substantially disposed in a single plane and are operably configured and associated in respect of one another to effect the transfer of drive signals therebetween by capacitive means, the gate drive circuit is a non-silicon-on-insulator CMOS integrated circuit, and high voltage isolation between the low and high voltage portions of the circuit is provided by the drive and sense electrodes.