Feed-Forward Converter Circuit for Supply Ripple Compensation
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Solution Overview
Problem
Conventional devices for processing digital signals suffer from supply current variations due to codeword changes, leading to performance degradation, harmonic distortion, and increased power consumption when addressing these issues with existing solutions such as reducing output impedance, increasing voltage regulator speed, or adding decoupling capacitance, which either increase power consumption or production costs.
Innovation Solution
A device and method that utilize a feed forward circuit to generate and supply the required current to the converter circuit based on known current consumption, allowing for over-compensation and pre-distortion of the converter circuit, independent of process, voltage, and temperature variations, thereby eliminating supply ripple and reducing spurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output impedance of the voltage supply is reduced to eliminate supply variations, then the supply voltage stability is improved, but the size of the LDO and current consumption increase significantly
Solution Approach 1:
The invention applies preliminary action by generating a compensation current in advance based on the digital input codeword before the supply variations occur. The compensation current is prepared and injected into the supply node proactively, preventing supply voltage variations rather than reacting to them after they occur. This eliminates the need for a large LDO with high current consumption while maintaining supply stability.
2Speed
If the speed of the voltage regulator is increased to reduce supply variations, then the response time is improved, but the power consumption increases significantly
Solution Approach 1:
The invention replaces the mechanical/electrical voltage regulator system with a digital compensation approach. Instead of increasing the speed of the voltage regulator (which consumes more power), the system uses digital logic to generate compensation currents that directly counteract supply variations. This substitution of the control mechanism eliminates the need for a high-speed, high-power voltage regulator while achieving the same supply stability goal.
3Reliability
If on-chip decoupling capacitance is increased to reduce supply variations, then the supply ripple is reduced, but the required area becomes very large
Solution Approach 1:
The invention extracts the function of reducing supply variations from the physical decoupling capacitance and transfers it to a digital compensation mechanism. By taking out the reliance on large on-chip capacitance and replacing it with an active compensation current generated from the digital codeword, the system achieves supply ripple reduction without requiring large area-consuming capacitors.
4Reliability
If dummy DAC cells are added to maintain constant current consumption, then the supply variations are reduced, but the overall current consumption increases
Solution Approach 1:
The invention changes the parameter of current consumption from constant (as with dummy cells) to dynamically compensated. Instead of maintaining a constant high current level with dummy cells, the system dynamically adjusts the compensation current based on the actual digital input codeword. This allows the total current consumption to match only what is necessary for the current output level, reducing overall power consumption while maintaining supply stability.
Data Source
AI summary
A device for processing digital signals is provided. The device comprises a digital signal source and a converter circuit having a current supply. The digital signal source outputs a codeword. The converter circuit receives the codeword from the digital signal source, receives a current at the current supply, and generates an output signal based on the codeword. The current is generated in accordance with the codeword.