Micromachining has become a miniaturization of key technology sensors. The ability to reduce the size of the sensing element allows for significant size reduction by using standard semiconductor fabrication techniques. The integrated signal processing further enhances the chance along the sensing element to reduce the size of the system, eliminating the need for additional pin links to external devices. The choice of micromachining technology can also determine the limitations of miniaturization, but this is usually determined by the type of sensor. Piezoelectric micromechanical components for pressure sensing have the opportunity to build a substrate from CMOS silicon, such as a separator on a surface, but can provide higher performance. Figure 1: Surface micromachined sensing elements. The sensor also reduces the effects of sensitivity and performance issues from calibration, although this can be mitigated by innovative design of the feature structure. This innovative design can also be used to integrate multiple components into a single sensor. This is most noticeable in 6-axis accelerometers, where well-designed elements can provide moving data as well as multiple axes. This also helps to miniaturize the system, replacing one sensor with multiple devices. However, the integration and miniaturization of this move comes at a price, usually in terms of noise and dynamic range. For example, adding filtering and signal processing to determine different forces on a composite sensing element and filtering out noise from different elements can result in a slower response time and limit the overall dynamic range. While this may be acceptable for small, space-constrained applications such as wearable electronics, it may not be suitable for small, unmanned aerial vehicles (UAVs) that have similar space limitations but higher accuracy requirements. . Plasma treatment The Kionix KXCJ9 is 3-axis silicon with a range of +/- 2g, ±4g or ±8g micromechanical accelerometers. The sensing components are built using Kionix's proprietary plasma micromachining technology. Acceleration sensing is based on the principle of differential capacitance from a sensing element that uses a common mode to dismiss the design of the sensing element to reduce the occurrence of this condition, resulting from motion changes, any erroneous acceleration caused by temperature. And environmental pressure. The sensing element is hermetically sealed into the device by a second silicon wafer cover using a frit using a hermetic package, rather than at the wafer level, which helps to reduce the overall size of the device. Figure 2: The Kionix KXCJ9 silicon accelerometer is housed in a closed cavity at the wafer level from the second bonded wafer. A separate signal processing ASIC is equipped with sensing elements to further reduce the overall size of the sensor, resulting in a 3&TImes; 3 & TImes; 0.9 mm LGA plastic package from 1.8 operation - 3.6 VDC power supply. The regulator is used to maintain a constant internal operating voltage over the input supply voltage range. In this way, it is possible to remove any errors from the supply variations by inputting stable operating characteristics within the range of the supply voltage, and eliminating the adjustment of the external power supply, further reducing the overall size of the design. Pressure sensing ST's LPS25H is an ultra-compact absolute pressure sensor with a built-in monolithic piezoresistive element developed by STMicroelectronics. This is done by suspending the film from a single monocrystalline silicon substrate, creating significantly smaller elements than the traditionally constructed silicon microfilm. The rupture film is protected by internal mechanical stops. This provides a range of 260 to 1260 hectopascals for measuring absolute pressure and can be applied to sports watch weather stations. Figure 3: The LPS25H can be placed in a 10-pin cavity through the LGA package (HCLGA) with a measurement of 2.5 & TImes; 2.5 & TImes; 1 mm and hiding to allow external pressure to reach the piezoelectric sensing element. The interface uses a standard CMOS process that allows highly integrated designs to be trimmed to better match the specific circuitry of the sensing component characteristics. manufacture. The entire measurement chain is composed of a low noise amplifier in which the resistance imbalance of the MEMS sensor (pressure, temperature) is converted to an analog voltage, which is provided to the user by embedding a 24-bit analog-to-digital converter (constituting the ADC) with a Output Data Rate (ODR), which is selectable from 1 Hz to 25 Hz, single trigger option. The LPS25H can be in a 10-pin cavity through the LGA package (HCLGA), which measures 2.5 x 2.5 x 1 mm and hides allowing external pressure to reach the sensing element. The use of a piezoelectric element allows its temperature range to operate from -30 ° C to + 105 ° C. Combined sensor Combining data from multiple axes of a micromechanical accelerometer is often used to alert the host processor that the device is to be activated, but this approach is also an increasingly part of the user interface supporting gesture interfaces. The combination of data usage enables system designers to further miniaturize devices by eliminating interface technologies such as keyboards and buttons. The Freescale MMA8451Q is a bulk micromachined triaxial, capacitive accelerometer that uses all three axes to provide the required data in a 3 x 3 x 1 mm QFN package with 14-bit resolution. The motion detection function can analyze changes in static acceleration or faster bumps. For example, the object to be tested is spinning, and all three axes will be enabled with a threshold detection of more than 2 grams. When the acceleration exceeds the set threshold, either as a fast or slow tilt, the motion can trigger an interrupt, depending on the threshold and timing value of the configured event. This condition will need to occur for at least 100 milliseconds to ensure that the event is not just noise. The timing value is passed through a configurable debounce counter that acts like a filter to determine if a condition exists for a set of configurable times (ie, 100 milliseconds or longer). There is also direction data provided in the source register to detect motion. This is useful for applications such as directional panning or flicking, which helps with algorithms for various gesture detections. There is a chance to obtain these two low-pass filtered data as well as high-pass filtered data, minimizing the need for bump detection and faster conversion data analysis. The acceleration data is passed through a high-pass filter, eliminating the offset (DC) and low frequency. The cutoff frequency of the high pass filter can be set by the user to four of the different frequencies depending on the ODR. A higher cutoff frequency ensures that DC data or slower moving data will be filtered out, allowing only higher frequencies to pass. Embedded transient detection with high-pass filtered data allows the user to set thresholds and debounce counters. The same way motion detection is used by the transient detection function by bypassing the high-pass filter, which provides greater flexibility to cover different ways that accelerometers can be used in a variety of customer designs. The accelerometer's static acceleration readings used by many applications measure the acceleration of the device purely by measuring the acceleration change from gravity. This is due to the fact that the acceleration data is filtered with a low pass filter in which the high frequency data is considered to be noise. However, there are many, among which the accelerometer must analyze the function of dynamic acceleration. Interface functions such as tap water, flick, wobble and step count are based on the analysis of the acceleration changes, which is simpler to explain using the dynamic components of the static acceleration data after the static components have been removed. The MMA8451Q has been embedded with a variety of customizable timers for setting the pulse time width and the time delay between pulses to support single/double and directional tap water detection. There are programmable thresholds and tap detection for all three axes that can be configured to pass through a high pass filter and also run through a low pass filter to provide more custom and tunable tap detection schemes. The status register provides information about the detected event, wherein the direction of the axis and the tap is updated. in conclusion Different micromachining techniques give designers a different optimization option for a miniaturized system. These ranges from integrated signal processing to reduce the overall size of the sensor that combines multiple data streams to eliminate another, larger device in the system in another way to reduce the overall size of the system. However, the choice of underlying sensor technology can limit the overall range and performance of the device, so careful consideration needs to be moved along to miniaturization. SWITCH SOCKET Guangdong Shunde Langzhi Trading CO., Ltd , https://www.langzhielectrical.com
