Differential Current Source With Cross-Coupled Noise Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Single-ended current sources used in microelectronic testing introduce noise into the output current due to referencing a ground, making accurate testing of electronic circuits difficult as the noise contaminates the output current, rendering it unusable.
Innovation Solution
A differential current source circuit is employed, featuring first and second amplifier circuits operating out of phase, coupled through a cross-coupling circuit with resistors, which maintains cross-coupling voltages to provide a constant differential current, rejecting common mode noise and allowing the load to float relative to the current source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-ended current source is used to provide output current, then the circuit structure is simple, but noise is introduced into the output current due to grounding reference
Solution Approach 1:
The patent divides the single-ended current source into two separate amplifier circuits (first and second amplifiers) that operate in a differential configuration. Each amplifier handles one side of the differential pair, segmenting the single ground-referenced path into two balanced paths that reject common-mode noise while maintaining circuit functionality.
Solution Approach 2:
The patent transitions from a single-ended (one-dimensional ground reference) architecture to a differential (two-dimensional balanced) architecture. By introducing a second reference path that is mirror-image to the first, the system adds a dimensional aspect that enables noise rejection through differential signaling while maintaining structural elegance.
2Object-affected harmful factors
If a differential current source with cross-coupling circuit is used, then noise is reduced and current constancy is maintained, but the device complexity increases
Solution Approach 1:
The patent merges the feedback functions of both amplifiers through the cross-coupling circuit. The cross-coupling resistors combine the output signals from both amplifiers and feed them back to各自的 opposite amplifiers, creating a unified noise-rejection mechanism that maintains current constancy while managing the complexity through functional integration.
Solution Approach 2:
The patent implements cross-coupling feedback where each amplifier's output is fed back to the other amplifier through resistor networks. This feedback mechanism continuously monitors and corrects deviations in the differential current, maintaining precision while the symmetric feedback paths cancel out common-mode noise signals.
3Ease of operation
If single-ended current source is used, then ease of operation is good, but measurement precision deteriorates due to noise contamination
Solution Approach 1:
The patent segments the single measurement path into two differential measurement paths. By measuring the difference between two balanced signals rather than a single ground-referenced signal, the system maintains operational simplicity while achieving superior measurement precision through noise cancellation in the differential configuration.
Data Source
AI summary
A current source circuit can include a first amplifier circuit and a second amplifier circuit. Each of the first and second amplifier circuits can be configured to generate respective amplifier output voltages based on a corresponding input voltage and respective feedback voltage. The current source circuit can further include a cross-coupling circuit that can include a first set of resistors and a second set of resistors. The first set of resistors can be configured to establish a first cross-coupling voltage based on the first amplifier output voltage and the second set of resistors can be configured to establish a second cross-coupling voltage based on the second amplifier output voltage. The first and second amplifier circuits can be configured to maintain the first and second cross-coupling voltage at a given voltage amplitude to provide a constant current at an output node of the current source circuit.