Bridge Sensor Readout Circuit With Zero-Crossing Node Switching
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Solution Overview
Problem
Existing sensor technologies face limitations in achieving fast and efficient biasing and readout of bridge sensor structures due to parasitic capacitance, which restricts dynamic response and requires significant stabilization time, leading to noise and offset issues, especially in high-speed applications.
Innovation Solution
A circuit and method that switch node connections near zero crossings of the excitation signal, using a non-constant periodic continuous excitation signal, allowing for reduced stabilization time and low noise readout, with integration-based low-noise amplification and zero-banding techniques to control transient effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spinning techniques are used for offset compensation by switching bias voltage between node sets, then offset compensation is achieved, but stabilization time increases due to parasitic capacitance and RC circuit behavior
Solution Approach 1:
The patent applies preliminary action by pre-charging or pre-discharging the parasitic capacitance through the switch network before the actual measurement phase. This preparation step reduces the transient response time required for the RC circuit to stabilize, allowing faster transition between spinning phases while maintaining offset compensation accuracy.
Solution Approach 2:
The patent implements periodic action through synchronized switching of the excitation signal and node configuration at regular intervals. By periodically alternating between different node connections and excitation phases, the system achieves continuous offset compensation while allowing the RC circuit to stabilize during each periodic cycle, thereby reducing overall stabilization time.
2Productivity
If node switching is performed abruptly between biasing and sensing configurations, then spinning operation is achieved, but transient signals and noise increase in the readout signal
Solution Approach 1:
The patent applies beforehand cushioning by introducing damping elements and controlled transition circuits that suppress transient signals generated during node switching. These cushioning measures are built into the switch network to absorb and dissipate the harmful transients before they can significantly affect the readout signal, thereby maintaining high spinning speeds with reduced noise.
Solution Approach 2:
The patent uses intermediary elements such as buffer circuits and transition switches that mediate between the abrupt node switching and the sensitive sensing circuitry. These intermediaries smooth out the switching transitions and isolate the sensing phase from transient disturbances, enabling faster spinning operations without excessive noise generation.
3Object-generated harmful factors
If low-noise amplification is implemented to reduce readout noise, then noise level decreases, but operation time must be extended to prevent noise aliasing
Solution Approach 1:
The patent applies preliminary action by performing low-noise amplification immediately after each switching phase while the signal is still stable and before noise aliasing can occur. This timing optimization allows the system to capture the amplified signal during its cleanest window, reducing the need for extended operation times while maintaining low noise levels.
Solution Approach 2:
The patent implements continuity of useful action by maintaining the low-noise amplification process continuously throughout the spinning operation, with each amplification phase seamlessly transitioning to the next. This continuous operation allows the system to accumulate useful signal data without interruption while keeping noise levels suppressed, thereby reducing the total operation time required.
Data Source
AI summary
A circuit for biasing and reading out a bridge sensor structure comprises at least two pairs of connection terminals. The circuit comprises an excitation signal generator for generating an excitation signal for biasing and/or exciting the bridge, in which the excitation signal is provided as a non-constant periodic continuous function of time, and a detection circuit for obtaining the sensor signal from the bridge sensor structure by electrically connecting the detection circuit to any pair of connection terminals while applying the excitation signal to another pair. The circuit comprises a switch unit for switching the electrical excitation signal and for switching the detection circuit. A controller controls the switch unit to switch the first pair from being connected to the excitation signal generator at a time when the generated excitation signal is in a predetermined signal range where the excitation signal value is substantially equal to zero.