Orthogonal detector circuit based on DDS chip phase shift

Abstract

The invention discloses an orthogonal detector circuit based on DDS chip phase shift. The circuit comprises a phase shift circuit, a first phase-sensitive detector, a first low-pass filter, a second phase-sensitive detector and a second low-pass filter. The phase shift circuit outputs a first reference signal to the first phase-sensitive detector and outputs a second reference signal to the second phase-sensitive detector. The first phase-sensitive detector conducts frequency mixing on an input signal and the first reference signal, and outputs a first sum frequency signal and a first difference frequency signal to the first low-pass filter. The first low-pass filter filters out the first sum frequency signal and outputs the first difference frequency signal Q (t). The second phase-sensitive detector conducts frequency mixing on the input signal and the second reference signal, and outputs a second sum frequency signal and a second difference frequency signal to the second low-pass filter. The second low-phase filter filters out the second sum frequency signal and outputs the second difference frequency signal I (t). According to the orthogonal detector circuit based on the DDS chip phase shift, the amplitude and phase of the input signal with the phase change can be accurately measured without the need of keeping the phases of the input signal and the reference signals identical or to be zero. The orthogonal detector circuit is simple, stable, reliable and easy to operate.

Description

technical field [0001] The invention belongs to the technical field of signal demodulation, and in particular relates to a phase-shifting quadrature detection circuit based on a DDS chip. Background technique [0002] There are more and more applications of signal demodulation technology based on quadrature detection, such as weak signal detection technology, communication technology and spectrum technology. How to extract useful signals from a lot of noise makes quadrature detection get a lot of attention. As described in Chinese invention patent CN103117973A, the core of an ordinary quadrature detection circuit is a phase-sensitive detector, and the performance of a phase-sensitive detector is mainly determined by an input signal and a reference signal, and the input signal can pass through a bandpass filter and a preamplifier Adjust it to meet the requirements of the system, and if the quadrature reference signal of the ordinary quadrature detection circuit is generated b...

AI Technical Summary

Problems solved by technology

[0007] The technical problem to be solved by the present invention is to use two DDS chips to form the phase shifting circuit of the quadrature detection circuit, which overcomes the problems that the phase shifting precision of the analog phase shifting circuit is not high and the common digital phase shifting circuit is complicated, and realizes that the output signal waveform is good, The signal frequency resolution can reach tens of millihertz, the phase resolution can reach tens of millidegrees or even several millidegrees, and the quadrature detection circuit based on DDS chip phase shifting is reliable and easy to operate.

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