Pressure sensor chips are micro-machined semiconductor devices that sense changes in pressure. Some devices produce an analog current or analog voltage that is proportional to the input signal. Others produce a digital parallel output signal, a pulse width modulation (PWM) output voltage, or a logic output based on threshold input values. Pressure sensor chips with serial interfaces allow communication with embedded microcontrollers and other digital systems. Common pressure measurements include absolute, gauge, differential, and vacuum pressure. Typically, pressure sensor chips are designed for medical, automotive, industrial, consumer product, and military applications. Sensors are manufactured as signal conditioning chips, stand-alone transducers, or integrated transducers that include both signal conditioning and the sensor on the same die.