Spectrometer and method for detecting a spectrum

A spectrometer for detecting a spectrum of a molecular species, comprising:

• an excitation and detection device, wherein the excitation and detection device is designed to couple an excitation signal into the excitation and detection device and to detect an analog background measurement signal and/or analog measurement signal,
• an arbitrary function generator, wherein the arbitrary function generator is designed to generate an analog cancelation signal, taking into account the detected background measurement signal or measurement signal,
• a first analog-to-digital converter for generating the spectrum of the molecular species, and
• a second analog-to-digital converter, wherein
• a) the arbitrary function generator is designed to generate the excitation signal, the second analog-to-digital converter is designed to receive the measurement signal and/or background measurement signal, and wherein the spectrometer is designed in such a way that the analog cancelation signal is phase-shifted by 180 degrees with respect to the analog background measurement signal detected by the excitation and detection device
• or
• b) the spectrometer comprises an up-converting mixer with a first local oscillator having a first local oscillator frequency and a down-converting mixer with a second local oscillator having a second local oscillator frequency different from the first local oscillator frequency, wherein the arbitrary function generator is designed to generate an input signal, the up-converting mixer is designed to generate the excitation signal from the input signal, the down-converting mixer is designed to generate an intermediate frequency background signal from the detected analog background measurement signal and to generate an intermediate frequency measurement signal from the detected analog measurement signal, the second analog-to-digital converter is designed to receive the intermediate frequency measurement signal and/or intermediate frequency background signal, and wherein the spectrometer is designed in such a way that the analog cancelation signal is phase-shifted by 180 degrees with respect to the intermediate frequency background signal generated by the down-converting mixer.