Silicon power microsensor with frequency range from DC to microwave

The authors introduce a thermal power sensor with an extremely wide bandwidth (DC to 26 GHz). The electrical signal to be measured is converted into thermal energy in a laser-trimmed 50- Omega -nichrome resistor which is arranged at the center of an anisotropically etched silicon diaphragm. The temperature increase of this heat source compared with the chip frame functioning as a heat sink is detected by means of a silicon-metal thermocouple. Across several orders of magnitude, its Seebeck voltage depends on the RMS value of the electrical input signal in an approximately linear manner. The authors show the theoretical considerations worked out to design the sensor, explain how it was implemented technologically, and present the results of the measurements performed to record its technical characteristics, which conform very well with the design calculations.<>