Integrated Electronics Piezoelectric (IEPE) is a type of transducer that is packaged with a built-in amplifier. Because the charge produced by some sensors is very small, the electrical signal produced by the transducer is susceptible to noise, and sensitive electronics must be used to amplify and condition the signal. An IEPE sensor integrates the sensitive electronics as close as possible to the transducer to ensure better noise immunity and convenient packaging. These sensors require a 4-20 mA current excitation to operate.
A charge mode sensor is a piezoelectric transducer which requires an amplifier, but unlike IEPE transducers, this amplifier is not built in. This separation of transducer and amplifier allows for the implementation of more complex amplifiers and filters because there is less constraints on physical space and power. The separation of piezoelectric element and signal conditioning also allows the transducer to operate over a higher temperature range. These sensors require no external excitation, but do require a device which has charge mode amplification.