Current Mirror Sample-and-Hold for Bias Noise Isolation
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Solution Overview
Problem
Current mirrors in electronic circuits amplify noise from the reference current, which can significantly degrade the performance of high-frequency circuits like radar devices by introducing noise into bias currents.
Innovation Solution
A current mirror circuit with a sample and hold mechanism using a switch and capacitor to disconnect the gate of the first transistor from the second transistor during specific phases, isolating the replica current path from noise in the reference current, thereby reducing noise propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current mirror circuit is used to generate bias current for high frequency circuits, then the operating point of electronic devices can be set, but noise from the reference current is amplified and degrades circuit performance
Solution Approach 1:
The current mirror circuit is divided into two independent paths: a reference current path and a replica current path. The replica current path is isolated from noise in the reference current path through the use of a switch that selectively connects or disconnects the gate of the second transistor from the gate of the first transistor, thereby segmenting the noise source from the sensitive output.
Solution Approach 2:
The noise component is extracted and removed from the replica current by selectively disconnecting the gate connection during phases when noise would be propagated. The switch extracts the harmful noise influence while maintaining the useful bias current generation function.
2Power
If the replica current is proportionally larger than the reference current (current mirror ratio > 1), then the bias current capability is enhanced, but the noise from the reference current is multiplied by the current mirror ratio
Solution Approach 1:
The switch operates periodically, connecting the gates during phases when noise filtering is not critical and disconnecting them during phases when noise would be amplified. This periodic connection and disconnection allows the circuit to maintain high bias current capability while periodically eliminating noise propagation.
Solution Approach 2:
The switch is configured to disconnect the gate connection in advance before noise would be significantly amplified, preventing noise propagation proactively rather than reacting to it after amplification occurs.
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
The solution effectively shields the replica current and output current from noise, enhancing the signal quality in high-frequency circuits by minimizing noise influence during critical operation phases.
Implementation Method 1
A capacitor is coupled between a gate of the second transistor of the replica current path and a first potential
Data Source
AI summary
The disclosure relates to a circuit including a current mirror circuit with a current path including a first transistor and a replica current path including a second transistor. The current path is connected to the replica current path to influence a current in the replica current path based on a reference current in the current path. The current in the replica current path may be proportional to the reference current. The circuit further includes a capacitor coupled between a gate of the second transistor and a first potential, a switch coupled between a gate of the first transistor and the gate of the second transistor to selectively disconnect the gate of the first transistor from the gate of the second transistor and from a first electrode of the capacitor. The disclosure further relates to a method for operating a circuit including a current mirror circuit.