Level-Shifting Sense Amplifier for Time Borrowing Across Voltage Domains
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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 communicate 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
1Loss of time
If traditional level-shifting circuitry is used, then voltage domain conversion is achieved, but time borrowing across voltage domains is not allowed
Solution Approach 1:
The sense amplifier is configured to transition between different operational states dynamically. During the transparent window, the amplifier allows its output to follow input changes, enabling time borrowing. After the transparent window closes, the amplifier locks to a hard resolved state, ensuring stability for subsequent operations. This dynamic state transition resolves the contradiction by providing both timing flexibility during the transparent period and stability afterward.
Solution Approach 2:
The circuit performs preliminary resolution of the input signal during the transparent window before the hard resolution phase. The soft resolution circuitry prepares the output signal in advance, allowing upstream circuitry to borrow time by changing outputs during the transparent window, while the secondary resolution circuitry maintains the signal after the window closes.
2Loss of time
If a transparent window is created for time borrowing, then timing flexibility is improved, but circuit complexity increases
Solution Approach 1:
The resolution process is segmented into two distinct phases: soft resolution during the transparent window and hard resolution after the window closes. The sense amplifier is divided into separate circuitry components - soft resolution circuitry that operates during the transparent window and secondary resolution circuitry that maintains the output afterward. This segmentation allows the circuit to provide timing flexibility when needed while maintaining simplicity in each individual phase.
3Adaptability or versatility
If soft resolution is used during the pulse, then time borrowing is enabled, but signal stability is reduced
Solution Approach 1:
The circuit dynamically transitions from a soft resolution state during the transparent window to a hard resolution state after the window closes. During soft resolution, the output can change to enable time borrowing. After the transparent window closes, the secondary resolution circuitry locks the output to a stable state, ensuring signal stability for subsequent operations. This dynamic state change resolves the contradiction between adaptability and stability.
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.