The Design of Lock-in Amplifier Based on DSP Builder

2013 ◽  
Vol 718-720 ◽  
pp. 733-738
Author(s):  
Qiang Zheng ◽  
Cheng Ma
Keyword(s):  
Background Noise ◽  
Narrow Band ◽  
Comb Filter ◽  
Weak Signal ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Dsp Builder ◽  
System Clock ◽  
Low Pass ◽  
Lock In

Lock-in amplifier is widely used to detect weak signals from significant background noise. In this paper, an FPGA-based Lock-in amplifier is implemented on the DSP Builder platform to measure impedance between biological cells and electrodes. To improve the measuring accuracy, a narrow band low pass filter with low cut off frequency was implemented. This low pass filter consists of a five-stage cascaded integrator-comb filter, two half band filters and a FIR low pass filter. Simulation shows that with a system clock of 10MHz, the cut off frequency of the low pass filter is lower than 20Hz. Experiments demonstrate that the implemented lock-in amplifier is able to detect weak signal with strong noise, making it an attractive approach to implement lock-in amplifiers which is more flexible and can meet the needs for specified measurements.

Weak Signal Detection System Based on Lock-in Amplifier Technology

2013 ◽  
Vol 389 ◽  
pp. 489-493
Author(s):  
Yong Lv ◽  
Chun Hui Niu ◽  
Yue Qiang Li ◽  
Qing Shan Chen ◽  
Xiao Ying Li ◽  
...  
Keyword(s):  
Signal Detection ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Weak Signal ◽  
Weak Signal Detection ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Phase Sensitive ◽  
Lock In

In order to detect the weak signal deeply buried in the noise, a weak signal detection system based on lock-in amplifier is proposed. The system includes the preamplifier circuit, active low pass filter circuit, AC amplifying circuit and phase sensitive demodulation circuit. Test results show that it can greatly increase the signal-to-noise ratio (SNR) up to 12.7db.

Rapid Recovery of Wide-Bandwidth Photothermal Signals via Homodyne Photothermal Spectrometry: Theory and Methodology

1993 ◽  
Vol 47 (4) ◽  
pp. 489-500 ◽  
Author(s):  
J. F. Power ◽  
M. C. Prystay
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Signal Recovery ◽  
Wide Bandwidth ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Filter Output ◽  
Low Pass ◽  
Four Quadrant ◽  
Lock In

Homodyne photothermal spectrometry (HPS) is a very wide bandwidth signal recovery technique which uses many of the elements of lock-in detection at very low cost. The method uses a frequency sweep, with a high-frequency bandwidth of up to 10 MHz, to excite a linear photothermal system. The response sweep of the photothermal system is downshifted into a bandwidth of a few kilohertz by means of in-phase mixing with the excitation sweep with the use of a four-quadrant double-balanced mixer and a low-pass filter. Under conditions derived from theory, the filter output gives a good approximation to the real part of the photothermal system's frequency response, dispersed as a function of time. From a recording of this signal, the frequency and impulse response of the photothermal system are rapidly recovered at very high resolution. The method has been tested with the use of laser photopyroelectric effect spectrometry and provides an inexpensive, convenient method for the recovery of high-frequency photothermal signals.

scholarly journals A CMOS Low Pass Filter for SoC Lock-in-Based Measurement Devices

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5173 ◽  
Author(s):  
Jorge Pérez-Bailón ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Dynamic Range ◽  
Current Trend ◽  
Cutoff Frequency ◽  
Oxide Semiconductor ◽  
Constant Current ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Compact Size ◽  
Low Pass ◽  
Lock In

This paper presents a fully integrated Gm–C low pass filter (LPF) based on a current steering Gm reduction-tuning technique, specifically designed to operate as the output stage of a SoC lock-in amplifier. To validate this proposal, a first-order and a second-order single-ended topology were integrated into a 1.8 V to 0.18 µm CMOS (Complementary Metal-Oxide-Semiconductor) process, showing experimentally a tuneable cutoff frequency that spanned five orders of magnitude, from tens of mHz to kHz, with a constant current consumption (below 3 µA/pole), compact size (<0.0140 mm2/pole), and a dynamic range better than 70 dB. Compared to state-of-the-art solutions, the proposed approach exhibited very competitive performances while simultaneously fully satisfying the demanding requirements of on-chip portable measurement systems in terms of highly efficient area and power. This is of special relevance, taking into account the current trend towards multichannel instruments to process sensor arrays, as the total area and power consumption will be proportional to the number of channels.

RETUNABLE REJECTION FILTERS

2021 ◽  
pp. 67-75
Author(s):  
I. M. Yasinskiy ◽  
A. I. Tyumentsev ◽  
A. N. Yakovlev
Keyword(s):  
Narrow Band ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

The possibilities of realizing retunable rejection filters are considered, in which two-pole networks are introduced into the low-pass filter, which play the role of narrow-band rejection circuits. Methods for analyzing rejection circuits and formulas for calculating elements are presented.

scholarly journals A Low Pass Filter With sub-Hz Cutoff Frequencies for a Portable On-Chip Lock-in Microinstrument

2018 ◽  
Vol 6 ◽  
Author(s):  
Jorge Pérez Bailón ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Dynamic Range ◽  
Output Stage ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Fully Integrated ◽  
Cutoff Frequencies ◽  
Compact Size ◽  
Low Pass ◽  
On Chip ◽  
Lock In

This paper presents a first-order single-ended fully-integrated Low Pass Filter (LPF) tunable from 114 mHz to 2.5 kHz, designed to conform the output stage of a portable lock-in amplifier requiring fc = 0.5 Hz, 5 Hz cutoff frequencies. It achieves the two target fc over a -40 to 120 °C range with a power consumption of 2.7 μW at 1.8 V supply, compact size and dynamic range above 80 dB.

Design and Research of Digital Decimation Filter Based on FPGA

2011 ◽  
Vol 105-107 ◽  
pp. 2086-2091
Author(s):  
Yao Li
Keyword(s):  
High Speed ◽  
Sampling Rate ◽  
Comb Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Cic Filter ◽  
Decimation Filter ◽  
Fpga Chip ◽  
Digital Down Conversion

This paper studies and analyses various digital filter and decimation structure. On this basis, by using QUARTUS development system design the decimation device modules, through the waveform simulation validated its correctness. Finally,a program is written into FPGA chip by the hardware platform. In the digital down conversion (DDC), CIC (cascade integral comb) filter plays an important role. It is mainly used for sampling rate, as well as low-pass filter effect. The main characteristics of CIC filter, using only adders, subtractor and register (no multiplier), so fewer resources occupied, implementation is simple and high speed. Based on the analysis of the principle of CIC filter,simulate and synthesize based on the theory of using VHDL language in FPGA. And successful application in the development of DDC chip. Keyword: CIC (cascade integral comb) filter,FPGA,VHDL

The Design of Digital Filter Based on DSP Builder

2014 ◽  
Vol 602-605 ◽  
pp. 2641-2644
Author(s):  
Xiao Li Hu ◽  
Li Ding ◽  
Zhi Gang Zhang
Keyword(s):  
Digital Filter ◽  
Hardware Description Language ◽  
Description Language ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Paper Model ◽  
Dsp Builder ◽  
Quartus Ii ◽  
Low Pass ◽  
Hardware Description

This paper model digital FIR low-pass by using the Toolbox of the DSP Builder in MATLAB and convert to VHDL hardware description language, compile and simulation through QUARTUS II software automatically, download and verified by EPF10K20RC208-4.The design combine MATLAB software with FPGA hardware organic ally and completes the transplant of the FIR low-pass filter.

Design of Lock-In Amplifier Based on Down-Sampling Mean Filter

2014 ◽  
Vol 543-547 ◽  
pp. 662-667
Author(s):  
Wen Tao Guan ◽  
Zhao Hua Yang ◽  
Yu Peng Cao
Keyword(s):  
Cross Correlation ◽  
Noise Suppression ◽  
Clutter Suppression ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Iir Filter ◽  
Low Pass ◽  
Mean Filter ◽  
Lock In ◽  
Good Detection

Low-pass filter is an integral part of lock-in amplifier, low-pass FIR or IIR filter is typically used in lock-in amplifier, which need a large number of multiplications and occupy more hardware resources. To reduce cross-correlation computing requirement of multiplications, this paper, designed orthogonal vector lock-in amplifier based on the down-sampling dual mean filter. Experiments show that, the digital amplifier has good detection performance and noise or clutter suppression. Keywords: lock-in amplifier, mean filter, down-sampling, Gaussian noise suppression, clutter suppression.

Sign in / Sign up

Export Citation Format

Share Document