Sensor Receiver Band-Pass Filter Without OP-Amps
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Solution Overview
Problem
Display devices with sensor units face challenges in minimizing filter size and power consumption while maintaining stable center frequency and Q factor, which are affected by manufacturing deviations, supply voltage, and temperature when operational amplifiers are used.
Innovation Solution
A sensor device with a band pass filter having multiple parallel paths, including input and output mixers, filters, and demodulators, which allows for stable center frequency and Q factor maintenance without operational amplifiers, reducing size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an operational amplifier (OP-amp) is used in the filter, then the filter can maintain stable center frequency and Q factor, but the size and power consumption of the filter increase
Solution Approach 1:
The patent removes the operational amplifier from the filter circuit entirely, extracting the problematic component that causes high power consumption. The filter is redesigned to function without the OP-amp, using only passive components (resistors and capacitors) in a parallel path configuration, thereby eliminating the source of excessive power consumption while maintaining filtering functionality.
Solution Approach 2:
The patent changes the fundamental operating parameters of the filter by transitioning from an active filter design (requiring OP-amp power supply voltage) to a passive filter design. The center frequency and Q factor are maintained through careful selection of resistor and capacitor values, achieving stability without relying on active components that consume power.
2Reliability
If an operational amplifier (OP-amp) is used in the filter, then the filter can maintain stable center frequency and Q factor, but the size of the filter increases
Solution Approach 1:
The operational amplifier is extracted and removed from the filter circuit, eliminating the need for additional space required by the active component. The resulting passive filter structure occupies significantly less area on the sensor substrate, directly resolving the size increase problem associated with OP-amp-based filters.
Solution Approach 2:
The patent uses multiple parallel paths with identical or similar RC component configurations, creating copies of the same filtering structure. This approach achieves the desired frequency response and stability through parallel combination of simple, compact units rather than requiring a single complex active filter section.
3Reliability
If the filter center frequency and Q factor are adjusted to compensate for manufacturing deviation, supply voltage, or temperature, then the filter performance can be maintained, but the device complexity increases
Solution Approach 1:
The passive filter structure inherently provides stability against manufacturing deviations, supply voltage variations, and temperature changes through its simple RC configuration. The filter does not require external adjustment mechanisms or complex compensation circuits because the passive components naturally maintain stable frequency and Q factor characteristics across varying conditions.
Solution Approach 2:
Instead of adding complex active components (OP-amps) to achieve stability, the patent inverts the approach by using a minimalist passive structure that achieves stability through simplicity. The solution goes against the conventional wisdom that active components are needed for stable filter performance, demonstrating that passive components can provide equal or better stability in this context.
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 decreases filter size and power consumption while maintaining stable center frequency and Q factor, independent of manufacturing deviations, supply voltage, and temperature variations.
Implementation Method 1
the sensor receiver includes a band pass filter including a plurality of paths connected in parallel
Implementation Method 2
a first path among the plurality of paths sequentially includes a first input mixer, a first filter, and a first output mixer
Data Source
AI summary
A sensor device includes: first sensors; second sensors generating a mutual capacitance with the first sensors; a sensor transmitter connected to the first sensors, the sensor transmitter supplying driving signals to the first sensors; and a sensor receiver connected to the second sensors. The sensor receiver receives sensing signals from the second sensors. The sensor receiver includes a band pass filter including a plurality of paths connected in parallel. A first path among the plurality of paths sequentially includes an input mixer, a filter, and an output mixer.