Shanghai China

Dual-channel Mini Lock-in Amplifier


Phase-locked amplification and demodulation techniques of weak signals have a wide range of applications in Turnable Diode Laser Absorption Spectrum (TDLAS) gas sensoring, Atomic Force Microscope (AFM) and Electrostatic Force Microscope (EFM) field. In order to meet various customers requirements, Healthy Photon developed a dual-channel micro-DSP phase-locked amplifier which integrates modulated digital signal generation, digital detector signal collection, synchronous phase-locked demodulation all in one. The highly integrated amplifier is equipped with the signal processing function which is required in TDLAS, AFM,EFM and other applications. It provides a more cost-efficient solution for researching/ industrial labs, industrial products and other applications.



· Internal synchronized reference frequency, no external reference signal needed

· Able to demodulate the weak signal down to 10nV with central frequency up to 400kHz

· Two independent LIA channels (each with independent X/Y/R/demodulation)

· Two DDS modulation outputs with respectively frequency, amplitude, and offset output signals adjustable

· Two low speed analog channels, output the demodulation results in real time

· USB virtual serial port to connect the host PC, minimalist phase-locked control interface

· Small size, portable, easy to integrate

· Flexible to configure the FPGA algorithm according to customers requirements


Product Photo 




Host PC Control Interface









10 cm x 11 cm


250 g

Power Supply

DC 5V/2A (within power supply board)


Analog In


AC 0.5 MHz

Input Impedance

1 Mohm

Input Noise

10nV/Hz1/2 (>10 kHz)

Voltage Range

-1V - +1V

Input Gain

1, 10


14 bit, 4 MSa/s

Analog Output


2 channels, -1V - +1V


DC 0.5 MHz


16 bit, 4 MSa/s


Demodulator and the reference phase

Number of channels

2 channels (internal reference)

Time constant

1ms, 10ms (customized version available)

Filter Bandwidth(Hz)

1000, 100 (customized version available)


1F, 2F, 3F, 4F

Reference phase resolution

1.0 degree


Auxiliary and others

AUX Output

2 channels, +-1V range


16 bit, 4 MSa/s

D/A Analog Bandwidth

10 kHz

Standard PC Interface

USB Virtual COM

General PC I/O (GPIOs


PID Control

(customized version available)


 Application case: TDLAS Oxygen detection

 Detecting principle diagram 



  Detecting result of Oxygen Absorption Signal

Comparison test

Detect surface micro-structure of SRAM chip sample by atomic force microscope (AFM).


AFM Experiment principle diagram


SRAM chip sample photo

You can see the basic structure of SRAM chip as above. The left image shows the scanned surface structure of normal AFM around 30μm.The right image integrates with SCM (scanning capacitance microscopy) technologies, includes the surface struction of semiconductor adulterated information.


Samples are provided by Bruker Company.




The phase-locked amplifier used in the test:

Bottom left: AFM internal phase-locked amplifier image(IL)

Bottom Middle: One commercial phase-locked amplifier image(model SR7230)(SR)

Bottom Left: Healthy Photon phase-locked amplifier image (HPC)

The time constants of all the phase-locked amplifiers used in this experiment are set as 1ms.


Image quality comparison

Under -5dB power, SCM output amplitude(dC/dV Amp) and Phase(dC/dV Phase)surface structure image quality comparison.

  dV Amp




dC/dV Phase





IL phase-locked amplifier

SR phase-locked amplifier

Healthy Photon phase-locked amplifier


Under -10dB power, SCM output amplitude(dC/dV Amp) and Phase(dC/dV Phase)surface structure image quality comparison.

dC/dV Amp




dC/dV Phase





IL phase-locked amplifier

SR phase-locked amplifier             Healthy Photon phase-locked amplifier




You can see from the comparison that using the phase-locked amplifier developed by Healthy Photon independently can achieve clearer image and higher image SNR than AFM/SCM. Healthy Photon focus on providing low cost, high quality weak signal phase-locked amplifiers and other products for customers, details please consult+86-21-61111380.


Shanghai Healthy Photon Co., Ltd. Reserved

ICP Recard: ICP14038530

Hotline: 86 21 61111380  Welcome to: 200 East Guoding Road, Shanghai, China