Integrated EMI filter circuit with ESD protection and incorporating capacitors

Patent metadata

Field	Value
Publication number	US-9246328-B2
Application number	US-201414486098-A
Country	US
Kind code	B2
Filing date	Sep 15, 2014
Priority date	Jan 15, 2013
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

An integrated electromagnetic interference (EMI) filter circuit with electrostatic discharge (ESD) protection and incorporating capacitors is provided. At least one passive element, i.e. resistor or inductor is connected between an input terminal and an output terminal. A first capacitor is connected between ground and the input terminal, and a second capacitor is connected between ground and the output terminal. A first diode and a second diode are connected in parallel to the first capacitor and the second capacitor. One or multiple parallel capacitors are connected in parallel to the passive element and between the input terminal and the output terminal for frequency compensation by employing the novel EMI LPF circuit, it is extraordinarily advantageous of enhancing its rejection band attenuation and meanwhile maintaining high cut-off frequency while implementation.

First claim

What is claimed is:

1. An integrated electromagnetic interference (EMI) filter circuit with electrostatic discharge (ESD) protection and incorporating capacitors, comprising:
a) a first passive element connected between an input terminal and an output terminal;
b) first and second capacitors, wherein said first capacitor is connected between ground and said input terminal, and said second capacitor is connected between ground and said output terminal;
c) first and second diodes, wherein an anode of said first diode is connected to ground, and a cathode of said first diode is connected to said input terminal, wherein an anode of said second diode is connected to ground, and a cathode of said second diode is connected to said output terminal, wherein said first diode comprises a first parasitic capacitance separate from said first capacitor, and said second diode comprises a second parasitic capacitance separate from said second capacitor; and
d) a first parallel capacitor connected in parallel to said first passive element, and between said input terminal and said output terminal for frequency compensation.

2. The integrated EMI filter circuit of claim 1 , wherein each of said first and second diodes comprises a Zener diode.

3. The integrated EMI filter circuit of claim 1 , wherein each of said first and second diodes comprises a silicon-controlled rectifier (SCR) structure.

4. The integrated EMI filter circuit of claim 1 , wherein said first parasitic capacitance is added to a capacitance of said first capacitor, and wherein said second parasitic capacitance is added to a capacitance of said second capacitor.

5. The integrated EMI filter circuit of claim 1 , wherein said first parallel capacitor comprises at least one of a metal-oxide-semiconductor (MOS) capacitor, a polysilicon-insulator-polysilicon (PIP) capacitor, and a metal-insulator-metal (MIM) capacitor.

6. The integrated EMI filter circuit of claim 1 , further comprising a third capacitor, a third diode, and a second passive element, wherein said first and said second passive element elements are connected in series between said input terminal and said output terminal, said third capacitor is connected between ground and a common node of said first and second passive elements, an anode of said third diode is connected to ground, and a cathode of said third diode is connected to said common node.

7. The integrated EMI filter circuit of claim 6 , further comprising a second parallel capacitor, wherein said first parallel capacitor is connected to said input terminal and said common node, and said second parallel capacitor is connected to said output terminal and said common node.

8. The integrated EMI filter circuit of claim 7 , wherein said second parallel capacitor comprises at least one of a MOS capacitor, a PIP capacitor, and a MIM capacitor.

9. The integrated EMI filter circuit of claim 6 , wherein said third diode comprises a Zener diode.

10. The integrated EMI filter circuit of claim 6 , wherein said third diode comprises an SCR structure.

11. The integrated EMI filter circuit of claim 6 , wherein said first, second, and third diodes are configured for said ESD protection.

12. The integrated EMI filter circuit of claim 1 , further comprising a third capacitor, a fourth capacitor, second and third passive elements, wherein said first passive element, said second passive element, and said third passive element are connected in series between said input terminal and said output terminal, said third capacitor is connected between ground and a first common node of said first and second passive elements, and said fourth capacitor is connected between ground and a second common node of said second passive element and said third passive element.

13. The integrated EMI filter circuit of claim 12 , comprising a second parallel capacitor, wherein said first parallel capacitor is connected to said input terminal and said second common node, and said second parallel capacitor is connected to said output terminal and said first common node.

14. The integrated EMI filter circuit of claim 13 , wherein said second parallel capacitor comprises at least one of a MOS capacitor, a PIP capacitor, and a MIM capacitor.

15. The integrated EMI filter circuit of claim 12 , further comprising a second parallel capacitor and a third parallel capacitor, wherein said first parallel capacitor is connected to said input terminal and said first common node, said second parallel capacitor is connected to said first and second common nodes, and said third parallel capacitor is connected to said second common node and said output terminal.

16. The integrated EMI filter circuit of claim 15 , wherein said each of said second parallel capacitor and said third parallel capacitor comprises at least one of a MOS capacitor, a PIP capacitor, and a MIM capacitor.

17. The integrated EMI filter circuit of claim 1 , wherein said input and output terminals are connected to a package lead-frame by bonding wires.

18. The integrated EMI filter circuit of claim 1 , wherein said first parallel capacitor comprises a lateral metal-metal finger capacitor.

19. The integrated EMI filter circuit of claim 1 , wherein said first parallel capacitor comprises a vertical metal-metal overlap capacitor.

Assignees

• Silergy Semiconductor Technology Hangzhou Ltd

Inventors

• Wang Albert Z
• Wu Wenchin
• Zhang Nan
• Wang Shijun

Classifications

• H10D84/204

  of combinations of diodes or capacitors or resistors · CPC title

• H02H9/044 Primary

  Physical layout, materials not provided for elsewhere (varistors H01C7/12; spark-gaps H01T; Ovshinsky devices H10N70/00) · CPC title

• H03H7/1766

  Parallel LC in series path (H03H7/1783 takes precedence) · CPC title

• H02H9/045

  adapted to a particular application and not provided for elsewhere · CPC title

• H03H7/1708

  Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path (H03H7/07 takes precedence) · CPC title