Digital lock-in amplifier based on CORDIC algorithm

A digital phase-locked and amplifier technology, applied in amplifiers, parametric amplifiers, amplifier types, etc., can solve the problems of limited noise and inability to change the precision of analog filters and analog multiplier devices, to avoid high-order harmonics, high precision Effect

Inactive Publication Date: 2010-01-13
ZHEJIANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are problems with parameter stability and flexibility in analog lock-in amplifiers, because once the analog circuit is determined, it cannot be changed
In addition, due to the limited accuracy of the analog filter and analog multiplier devices in the lock-in amplifier, they will also introduce noise

Method used

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  • Digital lock-in amplifier based on CORDIC algorithm
  • Digital lock-in amplifier based on CORDIC algorithm
  • Digital lock-in amplifier based on CORDIC algorithm

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Embodiment Construction

[0019] figure 1 As shown, the digital lock-in amplifier based on the CORDIC algorithm includes an input signal channel 1, an analog-to-digital converter 2, a PC controller 3, an RS232 serial port 4, a field programmable gate array 5, a first digital-to-analog converter 6, and a band-pass filter Device 7, second digital-to-analog converter 8, analog amplifier 9, analog bandpass filter 10, serial port receiving module 11, first adder 12, second adder 13, first CORDIC module 14, second CORDIC module 15 , output signal digital filter 16, output bias adjustment module 17; Signal channel 1 is connected with Field Programmable Gate Array 5 through analog-to-digital converter 2, and Field Programmable Gate Array 5 demodulates the input signal and passes through the second Digital-to-analog converter 8 outputs; Simultaneously, field programmable gate array 5 produces carrier signal, through first digital-to-analog converter 6, band-pass filter 7 output, provides carrier signal for syst...

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Abstract

The invention discloses a digital lock-in amplifier based on a CORDIC algorithm. A signal channel is connected with a field programmable gate array (FPGA) by an analog-to-digital (A / D) converter; the FPGA demodulates an input signal, outputs the input signal by a second digital-to-analog (D / A) converter, generates a carrier signal, outputs the carrier signal by a first D / A converter and a band-path filter and provides the carrier signal for a system; and a PC controller is connected with the FPGA by an RS232 interface and adjusts the phase, the frequency, the amplitude, the bias, and the like of a carrier to achieve the effect of real-time adjustment. The core module is realized on the FPGA, has high stability and flexible design, effectively inhibits drift noise caused by 1 / f noise, temperature, and the like, decides algorithm precision by an iteration number and a data word length, configures the amplitude, the phase and the frequency of a modulation signal by the PC controller, avoids the interference of odd frequencies of the input signal channel because of a sine wave used as a reference signal and is suitable for a bandwidth from 1Hz to 20MHz.

Description

technical field [0001] The invention relates to the field of weak signal detection, in particular to a digital lock-in amplifier based on a CORDIC algorithm. Background technique [0002] Lock-in Amplifier (Lock-in Amplifier, LIA) is a synchronous coherent detection instrument designed based on the principle of cross-correlation in the field of weak signal detection. Amplitude and phase of extremely weak signals in drift. The lock-in amplifier can improve the signal-to-noise ratio of the detection signal, and has been widely used in research work in the fields of physics, chemistry, biology, medicine, astronomy, communication, and electronic technology. Commonly used lock-in amplifiers are implemented by analog circuits, and the reference signal and input signal enter a phase-sensitive detector (PhaseSensitive Detection, PSD) composed of an analog multiplier and a low-pass filter, and finally output the result. Analog lock-in amplifiers have problems with parameter stabili...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F7/00H03D5/00
Inventor 鲍慧强马慧莲金仲和
Owner ZHEJIANG UNIV
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