Variability and aging sensor for integrated circuits

A system on a chip (SOC), comprising:

• a substrate having a semiconductor surface upon which said SOC is formed;
• said SOC including:
• digital circuitry, analog circuitry, and mixed-signal circuitry in and on said semiconductor surface;
• and
• a ring-oscillator-based on-chip sensor (OCS) in and on said semiconductor surface;
• including:
• an odd number of digital logic stages formed in and on said semiconductor surface including:
• a first stage and a last stage each including at least one NOR gate including a first gate stack and/or a NAND gate including a second gate stack;
• a feedback connection from an output of said last stage to an input of said first stage, and
• at least one discharge path including at least a first p-channel metal-oxide semiconductor (PMOS) device coupled between said first gate stack and a ground pad, or at least one charge path including at least a first n-channel metal-oxide semiconductor (NMOS) device coupled between said second gate stack a power supply pad.

A method for adaptively scaling voltage in an integrated circuit (IC), the method comprising:

• providing a ring-oscillator-based on-chip sensor (OCS), including a substrate having a semiconductor surface upon which said OCS is formed;
• said OCS including an odd number of digital logic stages formed in and on said semiconductor surface including a first stage and a last stage each including at least one NOR gate including a first gate stack and/or a NAND gate including a second gate stack;
• a feedback connection from an output of said last stage to an input of said first stage, and at least one discharge path including at least a first p-channel metal-oxide semiconductor (PMOS) device coupled between said first gate stack and a ground pad, or at least one charge path including at least a first n-channel metal-oxide semiconductor (NMOS) device coupled between said second gate stack a power supply pad,
• obtaining a frequency measurement from said OCS;
• determining a change in at least one voltage selected from VDD, Vbn and Vbp for said IC from said frequency measurement.