Current Mirror Common Mode Noise Attenuation
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Solution Overview
Problem
Current mirrors in electronic circuits are susceptible to common mode noise currents generated by voltage supply disturbances, which can negatively impact adjacent circuitry and reduce the power supply rejection ratio.
Innovation Solution
A system comprising a capacitor and two current mirror components with transistors, where the capacitor current is split into two parts, with one part flowing through a first transistor and the other part through a second transistor, proportionally sized, to attenuate common mode noise currents, thereby improving the power supply rejection ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current mirror circuit is used to provide bias currents, then the circuit functionality is improved, but common mode noise currents are generated that negatively impact adjacent circuitry
Solution Approach 1:
The current mirror circuit is divided into multiple components: a first current mirror component with a first transistor, a second current mirror component with a second transistor, and a capacitor. The capacitor current is segmented into first and second parts that flow through different transistors. This segmentation allows the circuit to provide the necessary bias currents while simultaneously attenuating common mode noise currents, resolving the contradiction between functionality and noise generation.
Solution Approach 2:
A capacitor is introduced as an intermediary element between the voltage supply rail and the current mirror components. The capacitor receives the capacitor current from the voltage supply rail and distributes it as first and second parts to different transistors. This intermediary structure enables the circuit to maintain its current mirror functionality while reducing the transmission of common mode noise currents to adjacent circuitry.
2Ease of manufacture
If voltage supply disturbances are present, then the circuit operates with standard components, but power supply rejection ratio is reduced
Solution Approach 1:
The circuit employs different configurations for the first and second current mirror components. The first current mirror component includes a first transistor with specific characteristics, while the second current mirror component includes a second transistor with different characteristics. This local differentiation in component quality and configuration allows the circuit to reject power supply disturbances more effectively while maintaining ease of manufacture using standard transistor components.
Data Source
AI summary
At least some embodiments are directed to a system comprising a capacitor coupled to a voltage supply rail and configured to carry a capacitor current that comprises first and second parts. The capacitor current is an alternating current (AC). A first current mirror component may couple to the capacitor and to the voltage supply rail and is configured to carry the first part of the capacitor current. A second current mirror component couples to the voltage supply rail and is configured to carry the second part of the capacitor current. The second part of the capacitor current is proportionally related to the first part of the capacitor current. A circuit couples to the second current mirror component. The capacitor and the first and second current mirror components are configured to attenuate a common mode noise current flowing to the circuit.