High Voltage Isolation Dual Capacitor Communication System

• US 20090206960A1
• Filed: 03/03/2009
• Published: 08/20/2009
• Est. Priority Date: 02/15/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Chow, Fun Kok, Lee, Kah Weng, Ng, Gek Yong
• Granted Patent: US 8,188,814 B2
• Time in Patent Office: Days
• US Class Current: 333/247
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/484 Connecting portions
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/48 Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
• CPC Class Codes: H01L 23/5223 Capacitor integral with wiring layers
• CPC Class Codes: H01L 23/642 Capacitive arrangements H01L23/49589, H01L23/645, H01L23/647, H01L23/66 take precedence; capacitive effects between wiring layers on the semiconductor body H01L23/5222
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection
• CPC Class Codes: H01L 28/60 Electrodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/12043 : Photo diode
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H04L 25/0266 : Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 5/14 : Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: Y10T 29/49117 : Conductor or circuit manufacturing

Abstract

According to one embodiment, there is provided a high voltage isolation dual capacitor communication system comprising communication drive and sense electrodes and corresponding first and second capacitors that are formed in two separate devices. The two devices are electrically connected in series to provide a single galvanicly-isolated communication system that exhibits high breakdown voltage performance in combination with good signal coupling. The system effects communications between drive and receive circuits through the first and second capacitors, and in a preferred embodiment is capable of effecting relatively high-speed digital communications. The system may be formed in a small package using, by way of example, CMOS or other semiconductor fabrication and packaging processes.

Claims

1. A high voltage isolation dual capacitor communication system, comprising:

a transmitter having a first capacitor comprising at least first and second communication drive electrodes separated by a distance d_tx and disposed in at least a first electrically conductive metallized layer, the first and second drive electrodes having a first capacitance C_tx therebetween, a first electrically conductive ground plane being spaced vertically apart from the first and second drive electrodes by a first electrically insulative layer, the first drive electrode being operably coupled to a drive input through a first node, a drive circuit being operably coupled to the drive input and configured to transmit a communication drive signal through the first capacitor;

a receiver having a second capacitor comprising at least first and second communication sense electrodes separated by a distance d_rx and disposed in at least a second electrically conductive metallized layer, the first and second sense electrodes having a second capacitance C_rx therebetween, a second electrically conductive ground plane being spaced vertically apart from the first and second sense electrodes by a second electrically insulative layer, the second sense electrode being operably coupled to a sense output through a second node, a receive circuit being operably coupled to the sense output and configured to receive the communication drive signal received by the second capacitor;

wherein the first and second capacitors of the transmitter and receiver, respectively, are connected electrically in series to permit the transfer of the communication drive signal through an electrical connection disposed therebetween, the first and second capacitors are configured to provide galvanic isolation between the transmitter and the receiver, a high voltage isolation distance of the system is defined by a sum of the distances d_tx and d_rx, and a voltage developed between the first node and the second node is shared and distributed between the first and second capacitors.

2. The system of claim 1, wherein the first and second drive electrodes are vertically stacked, the first drive electrode is disposed below the second drive electrode, and the first electrically conductive ground plane is disposed beneath the first and second drive electrodes.

3. The system of claim 1, wherein the first and second sense electrodes are co-planar and disposed horizontally within the same plane, and the second electrically conductive ground plane is disposed beneath the first and second sense electrodes.

4. The system of claim 1, wherein the first and second sense electrodes are vertically stacked, the first sense electrode is disposed above the second sense electrode, and the second electrically conductive ground plane is disposed beneath the first and second sense electrodes.

5. The system of claim 1, wherein the first and second drive electrodes are co-planar and disposed horizontally within the same plane, and the first electrically conductive ground plane is disposed beneath the first and second drive electrodes.

6. The system of claim 1, wherein the system has a breakdown voltage exceeding about 3,000 volts RMS when applied over a time period of about one minute.

7. The system of claim 1, wherein the system has a breakdown voltage exceeding about 4,000 volts RMS when applied over a time period of about one minute.

8. The system of claim 1, wherein the system has a breakdown voltage exceeding about 6,000 volts RMS when applied over a time period of about one minute.

9. The system of claim 1, wherein the second drive electrode is operably coupled to the first sense electrode to provide the series electrical connection between the first and second capacitors.

10. The system of claim 1, wherein the transmitter comprises an integrated circuit (IC), and the receiver comprises an IC.

11. The system of claim 10, wherein the transmitter and receiver ICs are encapsulated or overmolded to form a single package.

12. The system of claim 1, wherein the first electrically conductive metallized layer includes a first bond pad configured to have a first end of the electrical connection wirebonded thereto.

13. The system of claim 1, wherein the second electrically conductive metallized layer includes a second bond pad configured to have a second end of the electrical connection wirebonded thereto.

14. The system of claim 1, wherein the receiver and the transmitter are connected electrically to separate respective grounds.

15. The system of claim 1, wherein at least one of the first and second metallized layers comprise one or more of gold, silver, copper, tungsten, tin, aluminium, and aluminium-copper.

16. The system of claim 1, wherein at least one of the first and second electrically insulative layers comprises one or more of a semiconductor dielectric material, silicon oxide, silicon nitride and thick oxide.

17. The system of claim 1, wherein at least one of the first and second electrically conductive ground planes is formed of a semiconductor dielectric material or silicon.

18. The system of claim 1, wherein the transmitter is configured to transmit differential signals therethrough.

19. The system of claim 1, wherein the receiver is configured to receive differential signals therethrough.

20. The system of claim 1, wherein when a voltage ranging between about 2,000 volts RMS and about 6,000 volts RMS is placed across the first and second capacitors, the electric field densities resulting therein do not exceed about 400 volts/micron.

21. The system of claim 1, wherein at least portions of the transmitter or the receiver are fabricated using one or more of a CMOS process, a Bipolar-CMOS process, and a combined Bipolar-CMOS-DMOS (BCD) process.

22. The system of claim 1, wherein the system is encapsulated at least partially in polyimide or plastic.

23. The system of claim 1, wherein the receive circuit further comprises a common mode rejection (CMR) circuit.

24. The system of claim 1, wherein the system is configured to transfer data between the drive and receive circuits at a rate of up to about 300 Megabits per second.

25. A method of making a high voltage isolation dual capacitor communication system, comprising:

providing a transmitter having a first capacitor comprising at least first and second communication drive electrodes separated by a distance d_tx and disposed in at least a first electrically conductive metallized layer, the first and second drive electrodes having a first capacitance C_tx therebetween, a first electrically conductive ground plane being spaced vertically apart from the first and second drive electrodes by a first electrically insulative layer, the first drive electrode being operably coupled to a drive input through a first node, a drive circuit being operably coupled to the drive input and configured to transmit a communication drive signal through the first capacitor, and

providing a receiver having a second capacitor comprising at least first and second communication sense electrodes separated by a distance d_rx and disposed in at least a second electrically conductive metallized layer, the first and second sense electrodes having a second capacitance C_rx therebetween, a second electrically conductive ground plane being spaced vertically apart from the first and second sense electrodes by a second electrically insulative layer, the second sense electrode being operably coupled to a sense output through a second node, a receive circuit being operably coupled to the sense output and configured to receive the communication drive signal received by the second capacitor;

wherein the first and second capacitors of the transmitter and receiver, respectively, are connected electrically in series to permit the transfer of the communication drive signal through an electrical connection disposed therebetween, the first and second capacitors are configured to provide galvanic isolation between the transmitter and the receiver, a high voltage isolation distance of the system is defined by a sum of the distances d_tx and d_rx, and a voltage developed between the first node and the second node is shared and distributed between the first and second capacitors.

26. The method of claim 25, wherein the first and second drive electrodes are vertically stacked, the first drive electrode is disposed below the second drive electrode, and the first electrically conductive ground plane is disposed beneath the first and second drive electrodes.

27. The method of claim 25, wherein the first and second sense electrodes are coplanar and disposed horizontally with the same plane, and the second electrically conductive ground plane is disposed beneath the first and second sense electrodes.

28. The method of claim 25, wherein the first and second sense electrodes are vertically stacked, the first sense electrode is disposed above the second sense electrode, and the second electrically conductive ground plane is disposed beneath the first and second sense electrodes.

29. The method of claim 25, wherein the first and second drive electrodes are co-planar and disposed horizontally with the same plane, and the first electrically conductive ground plane is disposed beneath the first and second drive electrodes.

30. The method of claim 25, wherein the transmitter and receiver are incorporated into integrated circuits (ICs), and the ICs are at least partially encapsulated or overmolded to form a single package.