Xilinx, Inc.

Sing-Keng Tan

Xiaobao Wang

Gubo Huang

Andrew Tabalujan

Wenyi Song

Examples of the present disclosure provide example devices that include an integrated circuit that has debugging capability. In some examples, a device includes an integrated circuit die. The integrated circuit die includes an input/output (IO) base cell and a debug port. The IO base cell has an interface node and a feedback node. The interface node is configured to be coupled to memory, such as via an interposer, for communication therebetween. The IO base cell is configurable to selectively output to the feedback node a signal that is on the interface node. The debug port has an input node and an output node. The input node is electrically connected to the feedback node. The debug port is configurable to selectively output to the output node a signal that is on the input node. The output node is configured to be coupled to a pin exterior to the integrated circuit die.

Electronic device including integrated circuit with debug capabilities

Examples herein describe a die that includes a testing system (e.g., testing circuitry) for measuring the actual resistance of on-die resistors. When testing the die, an I/O element (e.g., a solder bump) can be used to sweep a voltage across the on-die resistor. The testing system identifies when the voltage across the on-die resistor reaches a predefined reference voltage and measures the corresponding current. Using the measured current and the reference voltage, the testing system can identify the actual resistance of the on-die resistor. In one embodiment, the on-die resistor is tunable such if the on-die resistor has a divergent value, the die can adjust its resistance value to the desired value.

On-die resistor measurement

A transmitter includes: a driver circuit having a pull-up circuit, and a pull-down circuit, coupled to an output pad; a digitally controlled impedance (DCI) calibration circuit having a first reference driver, a second reference driver, and a reference resistor, the DCI calibration circuit configured to: generate a value for a first code by calibrating a first impedance in the first reference driver against the reference resistor; generate a value for a second code by calibrating a second impedance in the second reference driver against the first impedance; and adjust the value of the first code to match the first impedance with the second impedance; and a pre-driver circuit configured to supply the first code and the second code to the driver circuit for adjusting output impedance of the pull-up circuit and the pull-down circuit.

Digitally controlled impedance calibration for a driver using an on-die reference resistor

An example a voltage regulator includes: a bias circuit coupled to an output node; a first operational amplifier having a first input coupled to the output node, a second input coupled to a reference voltage node, and an output coupled to a first node; a second operational amplifier having a first input coupled to the output node, a second input coupled to the reference voltage node, and an output coupled to a second node; an output transistor coupled between the output node and a ground node, the output transistor including a gate; first, second, and third stacked transistor pairs each serially coupled between the output node and the ground node, each transistor of the first, second, and third stacked transistor pairs including a gate; and switch circuits configured to selectively couple: the gates of the first and second stacked transistor pairs to the second node; and the gate of the output transistor to the first node.

Programmable reference voltage regulator

In an integrated circuit for an output interface, a comparator is used to compare a reference voltage and a regulated voltage to provide a comparison output. A state machine is coupled to the comparator to increment or decrement a resistance setting output of the state machine responsive to the comparison output. A reference single-ended driver is coupled to receive the resistance setting output from the state machine. An output node of the reference single-ended driver is coupled to a reference node. From the reference node, the reference voltage is input to the comparator as a feedback voltage. Transistors of the reference single-ended driver are set to be in either at least a substantially conductive state or at least a substantially non-conductive state responsive to the resistance setting output to provide an internal source termination resistance as a reference resistance.

Output driver and method of operating the same

Integrated circuits for an output driver and an output interface, as well as a method for operating an output driver, are described. In an embodiment of an integrated circuit for an output driver, a differential driver is coupled to a first single-ended driver at a first output node of the first single-ended driver and the differential driver. A second single-ended driver is coupled to the differential driver at a second output node of the second single-ended driver and the differential driver. The first single-ended driver provides a first source termination resistance for an open-drain mode of the differential driver, and the second single-ended driver provides a second source termination resistance for the open-drain mode of the differential driver.

An integrated circuit has a differential I/O buffer () capable of being operated in a single-ended mode. The I/O buffer includes circuitry (or) for reducing leakage current between the differential I/O pins (P, N) when an undershoot event occurs on a pin when operated single-ended mode. In one case, a differential termination circuit () includes a differential termination isolation circuit () that isolates the termination load () and termination load switch () from the single-ended pin. Alternatively or additionally, a differential output driver () of the I/O buffer switches a common bias voltage (ncom) to a supply voltage (V) in single-ended mode to insure the transistors (A, B) in the driver legs remain OFF during an undershoot event.

Growing community of inventors

San Jose, CA, United States of America

Sing-Keng Tan