Altera Corporation

Ker Yon Lau

Tat Hin Tan

Choong Kit Wong

Hoong Chin Ng

Hsiao Wei Su

An integrated circuit (IC) device includes a first input/output (I/O) buffer circuit. The first input/output buffer circuit includes first and second groups of stacked transistors. The first group of stacked transistors transfer signals formatted in accordance with only one signal protocol from the group of signal protocols. The second group of stacked transistors transfers the signals formatted in accordance with more than one signal protocols. In addition, integrated circuit device also includes a second input/output buffer circuit. The second input/output buffer circuit includes third and fourth groups of stacked transistors. The third group of stacked transistors transfers the signals formatted in accordance to the first signal transmission protocol from the group of signal transmission protocols. The fourth group of stacked transistors transfers the signals formatted in accordance to the plurality of signal transmission protocols from the group of signal transmission protocols.

Dual signal protocol input/output (I/O) buffer circuit

An input/output (I/O) circuit for an integrated circuit includes an input-output terminal, a termination circuit and an impedance compensation circuit. The termination circuit includes a node that is coupled to the input-output terminal. The termination circuit exhibits substantially constant first impedance below a first frequency of signals received at the input-output terminal. Furthermore, the termination circuit exhibits second impedance that is less than the first impedance when signals having a second frequency that is higher than the first frequency are received at the input-output terminal. The impedance compensation circuit is coupled to the input-output terminal. The impedance compensation circuit compensates for differences between the first and second impendences when the signal having the second frequency that is higher than the first frequency is received at the input-output terminal.

Integrated circuit with an increased signal bandwidth input/output (I/O) circuit

Duty cycle sampling circuitry is disclosed that may generate offsets that cancel each other out, thereby improving the accuracy of duty cycle sampling of input clock signals based on sampling clock signals. The input clock input signals may be swapped, or the sampling clock signals may be swapped, or both may be swapped, at various times. Erroneous samples obtained in one configuration can cancel out other erroneous samples obtained in another configuration.

Zero-offset sampling for clock duty cycle correction

Techniques are provided for capturing external signals at output pins on a programmable logic integrated circuit (IC) during a boundary scan test. A JTAG sample signal is routed to an input/output block on a chip and active during a JTAG sampling phase. An input buffer coupled to an output pin is turned on during the JTAG sample phase. Logic gates enable the input buffer in response to the JTAG sample signal so that the input buffer can capture a signal on the pin. The input buffer is turned off after the JTAG sampling phase to conserve power. The output buffer coupled to the pin that receives the test signal is tristated to prevent contention during the JTAG sampling phase. The techniques of the present invention can be used to test board level interconnects in less time and are easy to implement.

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Pearl Island, Malaysia

Ker Yon Lau