Dual-loop Compensation Suppresses Phase Noise Circuit of Quadrature Signal Source Based on Lock-in Amplifier
A lock-in amplifier and phase noise technology, applied in the direction of improving the amplifier to reduce the impact of noise, to achieve the effect of improving accuracy
Active Publication Date: 2017-02-15
JIANGSU SMART TECH
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Problems solved by technology
This single loop circuit only solves the tracking and part of the noise rejection
Method used
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Embodiment Construction
[0018] Embodiments of the invention will be described below with reference to the drawings.
[0019] A dual-loop compensation circuit based on a lock-in amplifier to suppress signal source phase noise, figure 1 It is a block diagram of the circuit structure of the present invention, including: comparator 1, #1 low-pass filter 2, integrator 3, 1 / 2V os Measuring circuit 4, phase-sensitive detection 5, frequency and phase detector 6, #2 low-pass filter 7, voltage-controlled oscillator 8, 1 / 4 frequency divider 9. Among them, comparator 1, #1 low-pass filter 2, integrator 3, 1 / 2V os Measuring circuit 4 and phase-sensitive detection 5 form a phase noise measurement and compensation loop; frequency and phase detector 6, #2 low-pass filter 7, voltage-controlled oscillator 8, and 1 / 4 frequency divider 9 form a digital phase-locked loop.
[0020] In specific implementation, the phase noise measurement and compensation loop is constituted as figure 2 , 1 / 4 frequency divider 9 output ...
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The invention discloses a dual-loop compensation orthogonal signal source phase noise restraining circuit based on a lock-in amplifier. An output orthogonal component of a quarter frequency divider is connected with the input side of a phase sensitive detector, and the output side of the phase sensitive detector is connected with the input negative terminal of an integrator. The output side of a half Vos measuring circuit is connected with the input positive terminal of the integrator. The output side of the integrator is connected with the input side of a #1 low pass filter. The output side of the low pass filter is connected the negative terminal of a comparator, and the output side of the comparator is connected with the input side of a phase frequency detector. The cophase component output side of the quarter frequency divider is connected with the input side of the phase frequency detector, the output side of the phase frequency detector is connected with the input side of a #2 low pass filter, the output side of the #2 low pass filter is connected with the input side of a voltage-controlled oscillator, and the output side of the voltage-controlled oscillator is connected with the input side of the quarter frequency divider. A signal source is connected with the input side of the phase sensitive detector, the input side of the half Vos measuring circuit and the input side of the comparator. The dual-loop compensation orthogonal signal source phase noise restraining circuit compensates for the phase offset caused by phase noise, and can effectively restrain the phase noise and ensure the eddy measuring accuracy.
Description
technical field [0001] The invention relates to the field of automatic control and detection of experimental instruments, in particular to a double-loop compensation circuit based on a lock-in amplifier for suppressing phase noise of a quadrature signal source. Background technique [0002] In the field of eddy current detection, since the detection signal is weak and easily submerged by noise, it is necessary to use a quadrature lock-in amplifier to detect the amplitude and phase of the signal. The system needs to be equipped with an excitation signal source with high frequency stability; at the same time, an orthogonal signal with the same frequency as the signal source is also required as a reference signal. The signal source is composed of semiconductor devices and electronic components, which will be affected by the temperature drift, aging and circuit noise of electronic devices to generate phase noise, which will cause phase jitter of the signal source, resulting in a...
Claims
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IPC IPC(8): H03F1/26
Inventor 江国栋杨燕赵蕾
Owner JIANGSU SMART TECH