Lock-in amplifier circuit for detecting terahertz pulse signals

Abstract

The invention belongs to the technical field of the detection of weak signals and particularly relates to a lock-in amplifier circuit for detecting terahertz pulse signals. The lock-in amplifier circuit comprises a photoelectric detector used for detecting the terahertz pulse signals, a pre-amplification module, a phase shift module and a phase-sensitive detection module. The lock-in amplifier circuit is characterized in that: signals to be detected which are acquired by the photoelectric detector are processed by the pre-amplification module and are connected to one input end of the phase-sensitive detection module; reference signals after the phase shifting operation by the phase shift module are connected to the other input end of the phase-sensitive detection module; the output end ofthe phase-sensitive detection module outputs signals; the pre-amplification module comprises a band-pass filter circuit and a second-order amplifying circuit which are sequentially connected; the phase shift module consists of a CD-951V4 chip and peripheral circuits of the CD-951V4 chip; and the phase-sensitive detection module consists of a CD552-R3 chip and periphery circuits of the CD552-R3 chip. The lock-in amplifier circuit can detect microvolt-level low-voltage signals with the noise of millivolt level, and is suitable for small-signal and intensive-background noise occasions such as signals acquiring of terahertz time-domain spectrometer, wherein the signal-to-noise ratio of output signals reaches over 50:1.

Description

technical field [0001] The invention relates to the technical field of weak signal detection, in particular to a highly integrated lock-in amplifier CD552-R3 circuit. Background technique [0002] In modern scientific research, with the in-depth development of science and technology, weak signal detection technology has become more and more important, and has become a comprehensive frontier topic in today's measurement technology. Using weak signal detection technology can measure such as weak current Signals, optical signals, magnetic signals and other tiny physical quantities that cannot be measured by traditional methods. Therefore, the weak signal detection technology has been paid more and more attention by modern science, and has developed rapidly. [0003] The noise of the general measurement system is a kind of interference signal, which is mainly composed of white noise and low-frequency noise. Usually, these noises cannot be eliminated by shielding and other metho...

AI Technical Summary

Problems solved by technology

Since the center frequency of the general filter is not stable, and the bandwidth cannot be set arbitrarily, it cannot be applied to occasions with high requirements for filtering noise.

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