DXA-001 Phase locked amplifier

DXA-001 Phase locked amplifier

 input signal channel

The low-noise analog front-end amplifier used in lock-in amplifier can effectively process differential or single-ended signals, and its equivalent input noise is only 5nV/√Hz. The input impedance of this channel is 10MΩ, and the input signal level can be detected at full scale output from 1nV to 1V. It can be applied to the measurement of input current signals, and the front-end variable current gain is 106 or 108 V/A.

reference signal channel

The DXA-001 digital lock-in amplifier can be used in either internal or external reference mode. When THE DXA-001 IS SET TO INTERNAL REFERENCE MODE, THE instrument's internal high-precision oscillator and digital synthesis algorithm can generate a sine wave signal that is multiplied by the input signal, and the internal reference signal is hardly affected by phase noise. Using digital phase shifting technology, the phase of the internal reference signal can achieve a resolution accuracy of 0.001°. The internal reference signal mode of the instrument can operate normally in the frequency range of 1 mHz to 102 kHz. In the external reference signal mode, the sine wave signal and TTL logic electric average can be used as the external reference signal. The rising or falling edge of the external reference signal triggers the internal phase-locked loop (PLL) to perform the locking action.

Display function

The DXA-001 uses a 5.6-inch TFT color screen with 640×480 resolution as the main display of the instrument. The data that can be detected by the lock-in amplifier, such as X, Y, R and θ values of the signal, can be displayed in numerical, bar chart, XY coordinate chart, polar coordinate display, etc.

Simultaneous measurement of multiple harmonics

In the traditional lock-in amplifier, only the fundamental frequency signal or some harmonic signal component can be measured at the same time. Therefore, the traditional lock-in amplifier is unable to meet the measurement requirements when the amplitude and phase of multiple frequency components are needed at the same time. The digital end of DXA-001 combines FPGA and ARM technology to achieve higher processing bandwidth and more flexible digital architecture. The digital processing accuracy can reach 48 bits, and the measurement of harmonics of 3 frequencies can be carried out at the same time, making a DXA-001 equivalent to 3 traditional lock-in amplifiers. The detected maximum harmonic signal frequency can reach 32767 times of the fundamental frequency, but the maximum harmonic frequency can not exceed the operating frequency of the instrument 102 kHz。

PC software operation

The internal RS232 to USB interface used in this instrument ensures that users can effectively use all test functions of DXA-001 on the control computer, including setting reasonable control parameters of the instrument and reading the data measured by the instrument. The instrument is equipped with the free LabVIEW program, which makes it easy to use the DXA-001 in complex scientific experiments. In the program interface of LabVIEW, the user can see all the control commands and the response of the instrument feedback.

 

 signal channel
Voltage input mode: single-ended or differential input
Full-Scale Sensitivity: 1 nV to 1 V in 1-2-5 steps
Current input gain: 106 or 108 V/A
Voltage: 10 MΩ//25 pF, AC or DC coupled
Current: 1 kΩ to virtual ground
Common Mode Rejection Ratio: >100 dB to 10 kHz, reduced by 6 dB/oct
Dynamic Reserve: >120 dB
Gain accuracy: standard 0.2%, maximum 1%
At 997Hz: 5 nV/√ Hz
Current noise:
At 97 Hz: 15 fA/√ Hz
At 997Hz: 13 fA/√ Hz
Power frequency filter: 50 Hz and 100 Hz

Frequency Range: 1 mHz to 102 kHz
Reference Input: Square or Sine Wave
Input impedance: 1 MΩ
Square wave reference level: VIH>3V, VIL<0.5V
Sine reference signal: >1 Hz 
Resolution: 0.001°
Absolute phase error:<1°
Relative phase error:<0.001°
Internal Reference: At 1 kHz:<0.0001°rms
External Reference: At 1 kHz: 0.005°rms (time constant 100 ms, 12 dB/oct)
Below 10 kHz:<0.01°/℃
Above 10 kHz:<0.1°/℃

Harmonic Detection: 2F, 3F, …nF to 102 kHz (n<32,767)

Internal Reference: Instant Acquisition

External reference: (2 cycles + 5ms) or 40ms

 

 Demodulator

Digital output: All settings are free of zero drift

Display: All settings have no zero drift
Analog output: All dynamic reserve settings are less than 5 ppm/°C

Harmonic Suppression: -90 dB

Time Constant: 10 us to 3 ks (<200Hz). 6, 12, 18, 24 dB/oct dip

10 us to 30 s (>200Hz). 6, 12, 18, 24 dB/oct dip

Sync filter: Effective below 200 Hz with 18,24 dB/oct dip