Sensor intelligence ranges from simple voltage signals or resistance changes all the way up to sophisticated modules that integrate the sensor along with control and communication functions.
The most basic of sensors are low accuracy, single components that change value based on the parameter they are intended to measure. For example, a thermistor will change resistance based on temperature. A decision is then made based on the resistance change as it generates a voltage that triggers a decision-making circuit. Rounding out the configuration is a constant current source that feeds the thermistor. In this configuration a level shift might trigger a shutdown. In more advanced configurations the level shift may enact certain control systems such as heating a process or cooling a process in order to reach an optimal temperature. Many sensors create low level signals. An amplifier stage boosts the signal to a level that enables the decision-making circuitry to function properly.
Automobile engines have become sophisticated to a level where optimal performance is achieved when the engine operates at a certain temperature. In this scenario cooling could be optimized by controlling a combination of fan speed and coolant flow. This is a large departure from the archaic open/close of a thermostat and the off/constant-speed-on of a cooling fan. The accuracy of these sensors might not be as crude as the thermostat that opens at 200 degrees and closes at 185 degrees. Instead, finer granularity might make the difference in achieving an additional mile per gallon of performance or increasing engine life.
Signal granularity is only a part of sensor intelligence. The granularity is often digitized. The more granularity, the more bits that are required to make the range of the numeric resolution. The combination of signal accuracy and bit rate determines the type of intelligence used in the ADC or Analog to Digital Converter.
Beyond the ADC sits the control circuit. Several types are used including microprocessors, DSPs, and FPGAs to name a few. Many of these devices in turn require sophisticated and dedicated software to process the information from the sensor intelligence.
Communication rounds out the sensor intelligence package. Depending on the location of the intelligence components and the amount of speed needed to communicate and make decisions, the communication can be serial or parallel in a manner similar to a computer motherboard. Transmission media also affects the communication protocol and technology as does configuration such as master/slave control of many sensor locations. Traditional synchronous protocols, such as I2C and asynchronous signals such as CAN bus, are used to carry sensor signals as well as the resulting control feedback signals. Communication devices have a physical layer for signal transmit and receive. Physical layer construction differs in wired application as well as wireless application. Often times, protection devices are required to protect the physical layer along with termination components for proper impedance matching. Additional components include a transmit media be it via wire or antenna.
Sensor intelligence affects cost in a manner similar to most electronic devices. The more sophisticated and accurate the intelligence, the more the cost that is added in nanoacres of silicon and intellectual property royalties. This creates a large market that ranges far and wide. In turn, there are many areas for companies to specialize from microprocessors to simple thermistors. The integration of these into control boards and modules creates further markets. These markets benefit distributors that offer diverse product lines. Often times it is more advantageous to combine components and parts from many companies rather than offering a single solution. The large portfolios of distributors, offer a more detailed solution in many cases.
Other advantages can be form factor and packaging. Modules made for controlled environments such as indoor applications would not fare well measuring pressure in an over the road truck. Therefore, markets expand into environmental package and performance based on applications and operating conditions.
As indicated in, How Sensors are Advancing Electronics Technology, Part 1 , of this sensor series, the sensor market will grow as products become more sophisticated. Sensor intelligence will expand along with it, as controllers base decisions on more and more data originating from the growing number of sensor locations and functions. Like all communications, the added bits and increased transmission speeds, along with the increase in accuracy and granularity will result in market growth for the digital sector. Transmission speeds will need to increase, memory sizes will expand to hold data, while software will be required to control the instruction sets. With projected markets in the billons in automobiles alone, the sensor business has a bright future in store.