Digital phase-locked amplifier with multiple reference modes

A technology of digital phase-locking and reference mode, which is applied to the automatic control of power and electrical components, etc. It can solve the problems that the signal phase is meaningless and the lock-in amplifier does not give a solution, so as to achieve the effect of simplifying the design

Active Publication Date: 2017-09-05
SUN YAT SEN UNIV
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

[0003] Although the theory of dual-phase lock-in amplification has been perfected, a lot of achievements have been made in signal amplitude measurement; but for phase measurement, only dual-phase lock-in amplification is not enough, and a phase-locked loop is required to phase the reference signal. Only when locked, can the phase of the signal under test be accurately measured; otherwise, only the amplitude of the signal can be measured, and the phase of the signal is meaningless
[0004] In addition, for some signal measurements that do not provide standard reference signals, such as the measurement of the resonance point of ultrasonic materials, such as the measurement of the signal phase difference between ultrasonic probes, the current lock-in amplifier does not provide a corresponding solution

Method used

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  • Digital phase-locked amplifier with multiple reference modes
  • Digital phase-locked amplifier with multiple reference modes
  • Digital phase-locked amplifier with multiple reference modes

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Embodiment 1

[0080] Such as figure 2 with image 3 As shown, this embodiment adopts the external reference mode, and its working principle is as attached image 3 As shown, the phase difference between the sinusoidal signal to be measured and the external reference signal is θ—that is, the phase value of the signal to be measured. In this mode, the analog link 1 has two channels, one of which is used to input the signal to be tested, and the other is used to input the reference signal.

[0081] In the external reference mode, that is, the phase difference between the sinusoidal signal to be measured and the external reference signal is θ—that is, the phase value of the signal to be measured.

[0082] Specifically, the external reference phase-locked loop 22 includes a sequentially connected multi-harmonic phase detector 221, a loop filter 222, a first multi-harmonic numerically controlled oscillator 223, and a first dual-way quadrature mixer 224 , the first low-pass filter 225 and the ...

Embodiment 2

[0106] In this embodiment, the reference phase-locked loop is a cross-reference phase-locked loop mode, and the cross-reference mode is for the measurement that does not provide a standard reference signal, or only needs to measure the phase difference between two channels of signals to be measured. The cross-reference mode includes two types: the known frequency of the signal to be tested and the frequency of the unknown signal to be tested. The working mode of the known frequency of the signal to be tested is included in the frequency of the unknown signal to be tested, so the following is only for the case of unknown frequency of the signal to be tested. describe.

[0107] The cross-reference mode has basically the same processing for the two input channels, one of which is called the reference channel as a reference point; the other is called the main channel, and its phase value is relative to the signal of the reference channel. The working process is as follows and attac...

Embodiment 3

[0155] The present embodiment is an internal reference mode, that is, the reference phase-locked loop is an internal reference phase-locked loop 24, and there are two working modes in it: 1, a single channel signal to be measured without a reference signal, and the signal frequency is unknown; 2, a lock-in amplifier A drive signal is provided for the circuit to be tested, and the frequency of the signal to be tested is known.

[0156] For the first working mode of the internal reference mode, it is similar to the single-channel cross-reference mode, as shown in the attached Figure 5 shown. Specifically, the internal reference phase-locked loop 24 includes a second frequency extractor 241, a third multi-harmonic numerically controlled oscillator 242, a third dual-way quadrature mixer 243, and a third low-pass filter connected in sequence. 244 and a third amplitude and phase calculation unit 245; where the signal to be measured is converted into two digital signals to be measu...

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Abstract

The invention discloses a digital phase-locked amplifier with multiple reference modes. The digital phase-locked amplifier comprises an analog link and digital module that are sequentially connected, wherein the digital module comprises a reference mode selector and multiple reference phase-locked loops that are connected with the reference mode selector in parallel; and a signal to be measured enters the analog link and is subjected to amplification, filtering and analog to digital conversion to form a digital signal to be measured, and the reference mode selector selects a corresponding reference mode to perform phase-locked amplification and complete the measurement of the phase and amplitude of the signal to be measured. The analog link comprises a low noise pre-amplifier, an anti-aliasing filter and an analog to digital converter that are sequentially connected; and the reference phase-locked loops comprise an external reference phase-locked loop, a cross-reference phase-locked loop and an external reference phase-locked loop. By adopting the digital phase-locked amplifier disclosed by the invention, the amplitude and phase can be simultaneously calculated, the overall structure is simple, and no analog circuit components need to be added.

Description

technical field [0001] The invention belongs to the technical field of electronics and weak signal measurement, in particular to a digital lock-in amplifier with multiple reference modes. Background technique [0002] The lock-in amplifier is a device used to measure weak signals. Because of its correlation operation, it obtains an extremely narrow measurement bandwidth, thereby reducing the introduction of noise, and can extract the required frequency signal in the background of strong noise, so it is widely used in Optical measurement, ultrasonic measurement, magnetic field weakening measurement and other fields. [0003] Although the theory of dual-phase lock-in amplification has been perfected, a lot of achievements have been made in signal amplitude measurement; but for phase measurement, only dual-phase lock-in amplification is not enough, and a phase-locked loop is required to phase the reference signal. Only when locked, can the phase of the signal under test be acc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/085H03L7/099
CPCH03L7/085H03L7/099
Inventor 王自鑫陈建宇蔡志刚郑紫元杨铃铃方俊伟李英生
Owner SUN YAT SEN UNIV
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