Low-Swing Clock Sequential Circuits for Dynamic Power Savings
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Solution Overview
Problem
High power consumption in digital integrated circuits due to large and complex clock propagation networks, which are exacerbated by the need for balanced clock distribution and the toggling nature of clock signals, leading to significant power consumption that can exceed 50% of overall power usage.
Innovation Solution
Implementing a low voltage swing clock signal by coupling input signals to transistors in a specific configuration, where the clock signal is reduced in voltage swing, allowing the output data signal to swing to the full voltage range even when the clock logic high level is below the supply voltage, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a balanced clock distribution network is implemented to maintain clock skew and jitter control, then clock signal integrity is improved, but power consumption increases significantly
Solution Approach 1:
The patent changes the voltage parameter of the clock signal from full swing (0 to VDD) to reduced swing (0 to a fraction of VDD, e.g., 0.5VDD). This parameter change allows the clock network to operate with lower power while maintaining sufficient signal integrity for controlling sequential elements, directly resolving the contradiction between signal integrity and power consumption.
Solution Approach 2:
The patent applies partial action by providing just enough voltage swing to achieve the required function (controlling latch/flop transitions) without excessive voltage amplitude. The reduced clock swing provides sufficient control authority for sequential elements while consuming significantly less power, avoiding the excessive action of full-voltage clock distribution.
2Productivity
If the clock signal toggles every clock cycle to control sequential elements, then circuit operation is maintained, but power consumption increases due to continuous switching
Solution Approach 1:
The patent changes the voltage amplitude parameter of the clock signal from full supply voltage swing to a reduced fraction of supply voltage. This allows the clock to continue toggling every cycle for proper circuit operation while reducing the energy lost in each switching event, thereby decreasing overall power consumption.
3Area of stationary object
If the clock tree size and load are increased to cover large semiconductor areas, then clock distribution capability is improved, but power consumption increases due to larger network size
Solution Approach 1:
The patent changes the voltage swing parameter of the clock signal to be lower than the full supply voltage. This allows the clock tree to distribute signals over large semiconductor areas with reduced power consumption, as each node in the expanded network consumes less power due to the reduced voltage transitions.
4Reliability
If buffering chains are carefully matched to control clock skew, then clock signal timing is improved, but device complexity increases
Solution Approach 1:
The patent changes the clock voltage parameter to a reduced swing level, which simplifies the buffering chain requirements. With lower voltage swings, the buffering chains need less precise matching and can be implemented with simpler circuits, reducing overall device complexity while maintaining adequate timing accuracy.
Data Source
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AI summary
Systems, apparatuses, and methods for implementing low voltage clock swing sequential circuits are described. An input signal (D) is coupled to the gates of a first P-type transistor (202) and a first N-type transistor (208) of a first transistor stack. A low voltage swing clock signal (CP) is coupled to the gate of a second N-type transistor (206) of the first transistor stack. An inverse of the input signal (DX) is coupled to the gates of a second P-type transistor (214) and a third N-type transistor (220) of a second transistor stack. The low-swing clock (CP) is coupled to the gate of a fourth N-type transistor (218) of the second transistor stack. A first end of one or more enabling P-Type transistors (210, 212) with gates coupled to the low-swing clock (CP) is coupled to the first P-type transistor's drain (202 drain), and a second end of the one or more enabling P-Type transistors (210, 212) is coupled to the second P-type transistor's drain (214 drain).