×

Sub-Micron high input voltage tolerant input output (I/O) circuit

  • US 20030094980A1
  • Filed: 12/19/2002
  • Published: 05/22/2003
  • Est. Priority Date: 01/09/2001
  • Status: Active Grant
First Claim
Patent Images

1. An apparatus for providing an input output from an integrated circuit, the apparatus comprising:

  • an input/output (I/O) pad;

    an upper pair of P-channel Metal Oxide Semiconductor (PMOS) devices, a first of the upper PMOS devices having source coupled to a power supply (VDDO) and drain coupled to source of a second upper PMOS device, the second PMOS device having drain coupled to the I/O pad;

    a lower pair of N-channel MOS devices (NMOS), a first of the upper NMOS devices having a drain coupled to the I/O pad and a source coupled to a drain of a second lower NMOS device, the second NMOS device having a source coupled to a ground potential;

    a first bias circuit coupled to a gate of the first upper PMOS device, said bias circuit providing a first bias voltage to the gate of the first upper PMOS device when the I/O pad is in an output mode and VDDO voltage otherwise;

    a second bias circuit coupled to a gate of the second lower NMOS device, said bias circuit providing a second bias voltage to the gate of the second lower NMOS device when the I/O pad is in an output mode and a ground voltage otherwise;

    a third bias circuit coupled to a gate of the second upper PMOS device, said bias circuit providing a third bias voltage, coupled to the gate of the second upper MOS device, the third bias voltage comprising a fixed voltage when VPAD is less than the VDDO voltage and comprising a voltage equal to VPAD otherwise; and

    a fourth bias circuit coupled to a gate of the first lower NMOS device, said bias circuit providing a fourth bias voltage to the gate of the first lower MOS device, the fourth bias voltage comprising a first fixed voltage when VPAD is less than a pre-determined value and comprising a voltage higher than the first fixed voltage otherwise.

View all claims
  • 5 Assignments
Timeline View
Assignment View
    ×
    ×