Floating Bias Generator Circuit for Automotive Switched Capacitor Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched capacitor circuits in automotive applications face issues due to permanent current flow from a bias resistor, causing voltage drops and corrupting measurements, especially when using PMOSFETs and requiring separate pins for sense and bias lines.
Innovation Solution
A circuit using a rectifier and charge pump to generate a local bias voltage, eliminating DC current flow and allowing for offset-free voltage generation, enabling the use of PMOSFETs or NMOSFETs and reducing design complexity by combining sense and bias lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias resistor is used to provide local voltage to floating switches, then the voltage supply is established, but permanent current flow causes voltage drops and corrupts measurements
Solution Approach 1:
The patent employs a switched capacitor circuit that operates periodically, using clock signals to alternately charge and discharge capacitors. This periodic operation allows the circuit to generate the necessary voltage levels for floating switches without requiring a permanent DC current path, thereby eliminating the voltage drops that corrupted measurements in the conventional bias resistor approach.
Solution Approach 2:
The patent introduces floating capacitors as intermediary energy storage elements between the clock generator and the floating switches. These capacitors are charged during specific phases of the clock cycle and then discharge to provide the required voltage to the floating switches, acting as a mediator that eliminates the need for a direct DC current path through the measurement circuitry.
2Reliability
If separate pins are used for sense and bias lines, then voltage supply is provided, but design complexity increases
Solution Approach 1:
The patent combines the sense and bias functions into a single integrated circuit structure. The switched capacitor circuit is designed such that the same floating nodes serve both as measurement points (sense) and as voltage supply points (bias) for the floating switches. This merging eliminates the need for separate pins and reduces design complexity while maintaining both functions.
Solution Approach 2:
The floating nodes in the patent serve multiple functions simultaneously: they act as measurement nodes for the sense amplifier, as voltage supply nodes for the floating switches, and as charge storage nodes for the switched capacitor circuit. This multi-functionality reduces the number of required pins and simplifies the overall circuit design.
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 provides a constant output voltage independent of the circuit potential, minimizing voltage drops and allowing for accurate measurements without additional pins, and enabling the use of various transistor types.
Implementation Method 1
a rectifier coupled to the alternating voltage providing circuit, the rectifier including a first rectifier terminal and a second rectifier terminal
Data Source
AI summary
In various embodiments a circuit is provided which may include a node at which a circuit potential may be provided; an alternating voltage providing circuit configured to provide a DC current free alternating voltage; a rectifier coupled to the alternating voltage providing circuit, the rectifier including a first rectifier terminal and a second rectifier terminal, wherein the first rectifier terminal or the second rectifier terminal may be coupled to the node; and a first output terminal and a second output terminal, wherein the first output terminal may be coupled to the first rectifier terminal to provide a first potential and wherein the second output terminal may be coupled to the second rectifier terminal to provide a second potential different from the first potential, the difference between the first potential and the second potential defining an output voltage, wherein the output voltage may be constant independent of the circuit potential.