A frequency response testing method for MEMS thermopile infrared detectors based on modulating the frequency of the input signal is proposed.Compared with traditional frequency response testing methods

this approach eliminates the need to know the absorber area or damage the package for the absorber area measurement of the device in the case of packaged detectors.It directly records the output voltage of the device to be tested

which simplifies the operation process and improving test efficiency.The detector is equivalent to a first-order thermoelectrical system.Infrared radiation is modulated with a sinusoidal harmonic signal

and the output voltage amplitude is collected.The collected data is normalized.The -3dB cut-off frequency point is fitted and located by using linear system theory

enabling the direct calculation of the response time.Experimental results demonstrate that the response times measured by the new method(8.38~9.52ms) are highly consistent with those obtained via the traditional responsivity/frequency curve method(8.37~9.69ms)

with a maximum deviation of only 1.8%.This ensures the test accuracy

keeps the tested devices intact

and supports multiple repeated measurements of the devices.This method opens up a new pathway for dynamic performance test of MEMS thermopile infrared detectors.