Single-Pin Retention Flip-Flop With Balloon Latch for Low-Power Data Hold
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Solution Overview
Problem
Sequential elements in digital electronic systems lose stored data when powered off during power down modes, as existing flip-flop circuits do not effectively retain data in reduced power states.
Innovation Solution
A low-power single retention pin flip-flop with a balloon latch is implemented, where a retention latch stores the flip-flop value during reduced power states, using a single retention pin to activate the latch and copy the data value, allowing it to be written back when the circuit is powered back up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage is reduced to ground reference voltage level during power down modes, then power consumption is reduced, but the stored data is lost
Solution Approach 1:
The flip-flop is divided into two independent storage elements: a main latch and a retention latch. The main latch is powered down to save energy while the retention latch remains powered to preserve data. This segmentation allows different power states for different parts of the storage system, resolving the contradiction between power reduction and data retention.
Solution Approach 2:
A retention latch acts as an intermediary storage element that receives data from the main latch before power down and transfers it back after power up. This intermediary structure enables data to be preserved during power down modes while allowing the main latch to be fully powered off for maximum energy savings.
2Reliability
If a retention latch is added to store flip-flop values during reduced power states, then data retention is improved, but device complexity increases
Solution Approach 1:
The retention latch is merged with the main latch to form an integrated flip-flop structure with unified control logic. The two latches share common control signals and are designed as a cohesive unit, minimizing the increase in device complexity while achieving reliable data retention during power down modes.
Solution Approach 2:
The retention latch serves multiple functions: it stores data during power down modes, maintains data integrity during transitions, and can be controlled by a single retention pin. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
3Reliability
If the retention latch is always enabled to store data, then data retention is ensured, but power consumption during normal mode increases
Solution Approach 1:
The retention latch is dynamically controlled through a retention pin that enables or disables the latch based on the power state. During normal operation, the retention latch is disabled to minimize power consumption. When power down mode is activated, the retention pin enables the retention latch to preserve data. This dynamic control resolves the contradiction between ensuring data retention and reducing power consumption during normal mode.
Data Source
AI summary
Systems, apparatuses, and methods for implementing a low-power, single-pin retention flip-flop with a balloon latch are described. A flip-flop is connected to a retention latch to store a value of the flip-flop during a reduced power state. A single retention pin is used to turn on the retention latch. During normal mode, the retention latch is pre-charged and a change in the value stored by the flip-flop does not cause the retention latch to toggle. This helps to reduce the power consumed by the circuit during normal mode (i.e., non-retention mode). When the retention signal becomes active, the retention latch gets triggered and the value stored by the flip-flop is written into the retention latch. Later, if the flip-flop is powered down and then powered back up while the circuit is in retention mode, the value in the retention latch gets written back into the flip-flop.