Signal Processor Current Limiter for Delta-Sigma Stability
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Solution Overview
Problem
High-speed signal processing circuits, such as Delta-Sigma converters, face instability due to high currents that can lead to overloading and parasitic capacitance issues, which existing technologies fail to effectively manage without interfering with normal operation.
Innovation Solution
A signal processor with a transconductor, current replicator, comparator, and current limiter that generates a replica current proportional to the output current, compares it with a reference, and adjusts the current output to prevent overloading by using a current limiter with variable impedance, ensuring accurate and fast current limiting without adding parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high current is supplied to the integrator for high-speed operation, then processing speed is improved, but circuit stability deteriorates due to overloading and parasitic capacitance
Solution Approach 1:
The current limiter proactively limits the current supplied to the integrator before overloading occurs. By monitoring and restricting the current in advance, the system prevents instability while maintaining high-speed operation capability.
Solution Approach 2:
The system dynamically adjusts the current parameter supplied to the integrator. The current limiter modifies the current level based on operating conditions, allowing high current for speed when stable, and reducing current when approaching instability thresholds.
2Reliability
If current limiting is implemented using existing technologies, then overloading is prevented, but normal operation is interfered with due to added complexity and parasitic effects
Solution Approach 1:
The current limiting function is merged with the existing transconductor and integrator circuitry. The current limiter shares the signal path and power supply with these components, eliminating the need for separate complex limiting circuits while preventing overloading.
Solution Approach 2:
The current limiter is designed to serve multiple functions: it limits current to prevent overloading, maintains signal integrity for normal operation, and works across different operating conditions. This multi-functionality reduces the need for additional dedicated circuits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents overloading and associated instability in the processing stage while maintaining normal operation of the signal processor, allowing for precise current limiting without affecting the transconductor or processing stage, thus ensuring accurate and fast operation.
Implementation Method 1
a voltage input signal is first converted into a current by means of a transconductance circuit
Implementation Method 2
The generated current charges or discharges a capacitor C. The resulting voltage across the capacitor C represents the integration of the current over time
Data Source
AI summary
A signal processor and method. The signal processor includes a signal current path. The signal processor includes a transconductor. The transconductor has an input operable to receive an input voltage of the signal processor. The transconductor also has an output operable to output a current based on the input voltage. The signal processor also includes a processing stage coupled to the output of the transconductor to receive and process the current outputted by the transconductor. The signal processor further includes a current replicator operable to generate a replica current proportional to the current outputted by the transconductor. The signal processor also includes a comparator operable to compare an output of the current replicator with a reference. The signal processor further includes a current limiter operable to limit the current outputted by the transconductor based on the comparison of the output of the current replicator with the reference.