Level-Shifting Sense Amplifier With Transparent Time-Borrowing Window
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Solution Overview
Problem
Traditional circuitry does not allow time borrowing across voltage domains, limiting the ability of circuits to relax edge-to-edge timing requirements and efficiently transfer signals between different voltage levels.
Innovation Solution
A level-shifting sense amplifier is configured to operate by generating an output at a different voltage level while allowing time borrowing, using pulse circuitry to create a transparent window for upstream circuitry to change its output during a pulse signal, enabling soft resolution during the pulse and hard resolution after, with secondary resolution maintaining the output until the next clock edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional level-shifting circuitry is used, then voltage domain isolation is maintained, but time borrowing across voltage domains is not allowed
Solution Approach 1:
A sense amplifier acts as an intermediary between voltage domains, enabling time borrowing while maintaining voltage domain isolation. The sense amplifier receives a clock signal from a first voltage domain, generates a pulse signal at a second voltage level, and uses this pulse to control resolution circuitry that transfers data between voltage domains during a transparent window, thus mediating the interaction between isolated voltage domains.
Solution Approach 2:
The circuit implements dynamic control of the transparent window through pulse-generated signals that enable resolution circuitry only during specific time periods. The resolution circuitry transitions between enabled and disabled states based on the pulse signal, allowing time borrowing to occur dynamically during the transparent window while maintaining isolation at other times.
2Reliability
If edge-to-edge timing requirements are strict, then signal integrity is maintained, but timing flexibility and circuit efficiency are reduced
Solution Approach 1:
The sense amplifier generates a pulse signal in advance of the actual data transfer operation. This pulse signal preemptively enables the resolution circuitry before the data needs to be transferred, creating a prepared state that allows flexible timing for the actual data change while ensuring signal integrity through controlled resolution.
Solution Approach 2:
The circuit uses periodic clock signals to generate corresponding periodic pulse signals that create regular transparent windows. This periodic structure provides predictable timing opportunities for data transfer between voltage domains, maintaining signal integrity through regular controlled intervals while providing timing flexibility within each period.
3Productivity
If a transparent window is created for time borrowing, then timing flexibility is improved, but circuit complexity increases
Solution Approach 1:
The sense amplifier serves multiple functions: it acts as a voltage level shifter, generates the pulse signal for the transparent window, and provides the clock signal for the resolution circuitry. By consolidating these functions into a single component, the circuit achieves timing flexibility without proportionally increasing overall circuit complexity.
Solution Approach 2:
The resolution circuitry combines the pulse signal generation with the data transfer function. The same circuit elements that generate the transparent window pulse also control the data resolution and transfer process, merging timing control and data transfer functions to reduce the number of separate components needed.
Data Source
AI summary
Techniques are disclosed relating to level-shifting circuitry and time borrowing across voltage domains. In some embodiments, sense amplifier circuitry generates, based on an input signal at a first voltage level, an output signal at a second, different voltage level. Pulse circuitry may generate a pulse signal in response to an active clock edge of a clock signal that is input to the sense amplifier circuitry. Initial resolution circuitry may drive the output signal of the sense amplifier circuitry to match the value of the input signal during the pulse signal. Secondary resolution circuitry may maintain a current value of the output signal after expiration of the pulse signal. This may allow the input signal to change during the pulse, e.g., to enable time borrowing by upstream circuitry.