This reference design provides a solution for a loop-powered: highly-accurate: field (sensor) transmitter with a HART® modem. The design uses a partially-discrete 4-mA to 20-mA current transmitter: HART modem: microcontroller: and power conditioning blocks in realizing a smart field transmitter design. The design is compliant with the HART FSK Physical Layer Specification and has been registered with FieldComm Group™.