Integrated RF switching cell built in CMOS technology and utilizing a high voltage integrated circuit diode with a charge injecting node

• US 5,786,722 A
• Filed: 11/12/1996
• Issued: 07/28/1998
• Est. Priority Date: 11/12/1996
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Buhler, Steven A., Mojarradi, Mohammad M., Lerma, Jaime
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US08/746,589
• Time in Patent Office: 623 Days
• Field of Search: 257/275, 257/379, 257/528, 257/532, 257/533, 257/536, 257/544, 327/493, 327/503
• US Class Current: 327/503
• CPC Class Codes: H01L 27/0629 in combination with diodes, or resistors, or capacitors

Abstract

An integrated CMOS diode with an injection ring that enables construction of an integrated CMOS RF switch. Construction techniques of using a diffused n-well resistor, parasitic capacitance and construction of the diode underneath a bonding input pad contribute to performance of the switch as well as saving space needed to construct the switch.

Claims

1. A CMOS integrated RF switch comprising:

a) an RF signal input node,

b) a logical input node,

c) a diode with an anode, cathode, and charge injecting node, with the cathode being connected to said RF signal input and the anode being connected to ground,

d) a charge injecting node driver with an input and an output which is capable of driving a negative signal and up to at least a 0 volt signal, with the charge injecting node driver input connected to said logical input and the charge injecting node driver output connected to the charge injecting node of said diode,

e) a high voltage level translator with an input and an output, with the high voltage level translator input connected to said logical input,

f) a high voltage driver with an input and an output, with the high voltage driver input connected to the high voltage level translator output, and

g) an RC filter connected between the high voltage driver output and said RF signal input.

2. The RF switch of claim 1 wherein said diode resides in a substrate and comprises:

a) a substrate with an upper portion and a lower portion wherein the upper portion has an upper portion depth and an upper portion surface, and the lower portion is substantially uniformly heavily doped with a first carrier type and has a lower portion depth,

b) an anode area lightly doped with a first carrier type in the upper portion of said substrate, said anode area having an anode area width and an anode area depth,

c) a cathode area contiguous with the anode area and completely surrounding the anode area at least at the upper portion surface doped with a second carrier type, said cathode area being in the upper portion of said substrate, having a cathode area depth which is less than the upper portion depth of the upper portion of said substrate wherein there is a portion of said anode area between said cathode area and the lower portion of said substrate, and said cathode area having a cathode area width,

d) a third area contiguous with the cathode area and completely surrounding the cathode area at least at the upper portion surface, said third area also being contiguous with the portion of said anode area between said cathode area and the lower portion of said substrate, said third area being doped identically to the anode area and having a third area width, and

e) an injecting node contiguous with the third area and substantially surrounding the third area at least at the upper portion surface that is heavily doped with the second carrier type, said injecting node having an injecting node depth that is less than cathode area depth wherein there is a portion of said third area between said injecting node and the lower portion of said substrate and said injecting node having an injecting node width.

3. The RF switch of claim 2 wherein the first carrier type is a p type and the second carrier type is an n type.

4. The RF switch of claim 2 wherein the first carrier type is an n type and the second carrier type is a p type.

5. The RF switch of claim 2 wherein the anode area is circular, the cathode area is annular, the third area is annular, and the injecting node is substantially annular.

6. The RF switch of claim 1 wherein said high voltage level translator comprises a cascode pair.

7. The RF switch of claim 1 wherein the RF switch resides in a substrate, said RF signal input node is constructed as a pad on top of said substrate and overlays said diode.

8. The RF switch of claim 1 wherein said RC filter comprises a resistor with two ends wherein one end is connected to said RF signal input node and the other end is connected to said high voltage driver output, and a capacitor with two ends wherein one end is connected to said high voltage driver output and the other end is connected to ground.

9. The RF switch of claim 8 wherein the RF switch resides in a substrate and said resistor is constructed as a diffused n-well resistor.

10. The RF switch of claim 8 wherein the RF switch resides in a substrate and said capacitor is constructed utilizing a parasitic capacitance.

11. The RF switch of claim 1 wherein the charge injecting node driver is capable of driving a signal from -1 volt to +5 volts.