Output buffer with self-adjusting slew rate and on-chip compensation

In this paper, two circuits are proposed to effectively control IC noise. The first circuit is a modified I/O circuit that monitors the local output switching condition, and intelligently adjusts its slew rate such that the I/O can switch as fast as it is allowed without jeopardizing noise performance. The second circuit is a PVT-compensation control circuit, which senses process, voltage, and temperature variations, and compensates the I/O circuit's current drive accordingly. This feature makes the I/O circuits more robust under a range of environmental stresses. From analyses and simulations, the proposed I/O and PVT-compensation control circuits demonstrate robustness in terms of IC noise control. They control IC noise to less than 10% variation between single and multiple output switchings as compared to a conventional I/O circuit with 56% variation.