On-Die Voltage Difference Measurement Using VCO Frequency Counting
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Solution Overview
Problem
Current methods for on-line current estimation in integrated circuits are inadequate for accurately measuring small voltage differences across pass devices, which is crucial for power management and validation, especially in multiple gated power domains, as they can impact optimization and reliability.
Innovation Solution
A system comprising a pair of voltage-controlled oscillator circuits connected to terminals of a pass device, with counter circuits to count oscillation periods, allowing for precise on-die voltage difference measurement without relying on high voltage differences, thereby estimating current consumption accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage measurement methods are used, then measurement capability is provided, but measurement precision is insufficient for small voltage differences
Solution Approach 1:
The patent transforms the voltage measurement problem into a frequency measurement problem by using voltage-controlled oscillators. The voltage difference across the pass device modulates the oscillation frequency, which is then counted over a predetermined time period. This parameter transformation enables precise measurement of small voltage differences that would be difficult to measure directly with conventional voltmeters.
Solution Approach 2:
The patent replaces direct electrical voltage measurement with a temporal counting mechanism. Instead of measuring voltage directly with an analog or digital voltmeter, the system uses voltage-controlled oscillators whose oscillation periods are counted by counters. This substitution of measurement methodology improves precision for small voltage differences.
2Measurement precision
If voltage drop measurement is performed across pass device, then current estimation is achieved, but process reliability may be impacted
Solution Approach 1:
The patent measures only the voltage difference across the pass device rather than the absolute voltage levels. This partial measurement approach focuses the measurement on the relevant parameter (voltage drop) while minimizing the impact on the overall system. The measurement is performed non-invasively by tapping only the voltage difference, which does not significantly load or disturb the pass device operation.
3Measurement precision
If on-line current estimation is implemented, then power management capability is improved, but power consumption increases
Solution Approach 1:
The patent uses periodic oscillation and counting over a predetermined time period to measure voltage difference. The measurement is performed in discrete time intervals rather than continuously, which reduces the average power consumption while still providing accurate current estimation. The counters are reset and restarted for each measurement cycle, enabling periodic rather than continuous operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate current estimation through voltage drop measurement with minimal impact on process reliability, power consumption, and thermal dissipation, suitable for various integrated circuits including microprocessors and power gating switches.
Implementation Method 1
a first voltage controlled oscillator circuit (16) having a first voltage control input (18) connectable to a first terminal (20) of the pass device (14)... providing, by the first voltage controlled oscillator circuit (16), a first output signal (32)... a second voltage controlled oscillator circuit (22) having a second voltage control input (24) connected to a second terminal (26) of the pass device (14)... providing, by the second voltage controlled oscillator circuit (22), a second output signal (34)
Data Source
AI summary
A system for on-die voltage difference measurement on a pass device comprises a first voltage controlled oscillator circuit having a first voltage control input connectable to a first terminal of the pass device; a second voltage controlled oscillator circuit having a second voltage control input connectable to a second terminal of the pass device; a first counter circuit arranged to count oscillation periods of a first output signal from the first voltage controlled oscillator circuit and to provide a stop signal when a predefined number of the oscillation periods of the first output signal is counted; and a second counter circuit arranged to count oscillation periods of a second output signal from the second voltage controlled oscillator circuit and to stop counting depending on the stop signal.