Competing-Path Ring Oscillator for Direct Latch Timing Window Measurement
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Solution Overview
Problem
Current methods for measuring latch hold-times in computer systems rely on simulations, which often result in inaccurate predictions and the addition of guard-band margins, leading to reduced performance and increased costs due to differences between simulation estimates and actual performance.
Innovation Solution
A method and apparatus for direct measurement of latch timing window parameters using a competing path ring oscillator circuit, where a start-up pulse is delayed through a ring oscillator circuit to determine the oscillating state, allowing for the direct measurement of setup and hold times by configuring delay blocks with varying delay times and combining outputs for multiplexed signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simulation methods are used to estimate latch hold-times, then measurement complexity is reduced, but measurement precision deteriorates due to differences between simulation predictions and actual performance
Solution Approach 1:
The ring oscillator circuit automatically measures its own timing parameters through self-oscillation. The circuit uses the latch circuit under test as an integral component, and the oscillation characteristics directly reveal the timing window parameters without requiring external measurement equipment or complex test setups.
Solution Approach 2:
The patent uses electrical oscillation in the ring oscillator circuit to measure timing parameters. By analyzing the oscillation frequency and behavior of the circuit, the latch timing window parameters can be directly determined through the relationship between oscillation period and delay elements.
2Reliability
If guard-band margins are added to simulation estimates, then reliability is improved, but productivity deteriorates due to reduced performance
Solution Approach 1:
The patent replaces simulation-based estimation with direct hardware measurement using ring oscillator circuits. This substitution provides accurate timing parameter data that eliminates the need for conservative guard-band margins, allowing the latch circuits to operate at their true performance limits without sacrificing reliability.
3Measurement precision
If direct hardware measurement methods are used for latch timing parameters, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The ring oscillator circuit serves multiple functions: it generates clock signals, provides delay elements, and simultaneously measures the timing parameters of the latch circuit. This multi-functionality reduces the need for separate dedicated measurement circuits, thereby limiting the increase in overall device complexity.
Data Source
AI summary
Direct measurement of a latch timing window includes, for each of a plurality of predetermined delay times: providing a first signal to a data input of a first latch of a ring oscillator circuit via a delay block configured to delay the first signal by the predetermined delay time; providing the first signal to a first logic clock buffer (LCB); generating a clock signal by the first LCB responsive to receiving the first signal; providing the clock signal to a clock input of the first latch; and determining from an output of the ring oscillator circuit that the ring oscillator circuit is in either an oscillating state or a non-oscillating state. At least one timing window parameter for the first latch is determined based on one or more of the plurality of delay times that are associated with an oscillating state of the ring oscillator circuit.