Overview

The OE1311/OE1351 modular lock-in amplifier is a high-performance, cost-effective measurement instrument. Based on digital modulation, output filters, and a high-precision 24-bit digital-to-analog converter (ADC) with the new Zynq architecture, it is capable of accurately and quickly measuring the effective signal components that are submerged in loud noise. Moreover, the OE1311/OE1351 lock-in amplifiers are capable of simultaneously measuring the amplitude and phase information of the input signal, which is comparable to the international top technology in the same industry in terms of core parameters such as measurement accuracy, operating frequency range, signal-to-noise ratio, and dynamic reserve. Meanwhile, newly developed functions such as multi-harmonic measurement, oscilloscope, spectrum analyzer, etc. make the OE1311/OE1351 functions can meet a variety of scientific research and industrial uses.

Input Signal Channels

The low-noise analog front-end amplifiers used in the lock-in amplifiers OE1311/OE1351 are capable of efficiently processing differential or single-ended signals with an equivalent input noise of 5 nV/√Hz. 10 MΩ input impedance is used for this channel, and the input signal level can be detected at full-scale output from 1 nV to 5 V. In addition, the OE1311/OE1351 can be used for a wide range of scientific and industrial applications. In addition, the OE1311/OE1351 can be used to measure input current signals with a front-end variable current gain of 10^6 V/A. The OE1311/OE1351 has a dynamic range of 120 dB or more, and the internal programmable gain amplifier can be adjusted according to the amplitude of the input signal to change the dynamic reserve of the entire system. The high-precision 24-bit ADC has a sampling rate of 4MSPS, and an anti-alias filter in front of the ADC effectively prevents signal aliasing.

Reference Signal Channel

The reference signal of OE1311/OE1351 digital lock-in amplifiers can be selected as either a sine wave signal or a square wave signal according to the user's actual situation, and also can utilize the digitally synthesized reference signal inside the instrument. When the OE1311/OE1351 is set to the internal reference signal mode, the instrument's internal high-precision oscillator and digital synthesis algorithm can generate a sine wave signal for multiplication with the input signal, and the internal reference signal at this time is virtually unaffected by phase noise. The phase of the internal reference signal can be resolved with an accuracy of 1 udeg using digital phase shifting. The internal reference signal mode of this instrument can work properly in the frequency range of 1uHz to 100/500kHz. In addition, the OE1311/OE1351 is also capable of using an external reference signal mode, where sine wave signals and TTL logic levels can be used as external reference signals. The rising or falling edge of the external reference signal triggers the internal phase-locked loop (PLL). Based on the frequency of the reference signal, the OE1311/OE1351 can detect signal harmonics. The maximum harmonic signal frequency it can detect is 65535 times the fundamental frequency, but the maximum harmonic frequency cannot exceed the instrument's operating frequency of 100/500 kHz.

Filters

The core component of the OE1311/OE1351 is the modulator. In contrast to analog signal multipliers, the digital modulator inside this instrument effectively curtails potential measurement errors caused by DC offsets and misalignments. The multiplication of the coherent signals inside the digital modulator is optimized to minimize the computational error, ensuring that the instrument can accurately detect weak input signals.The time constants of the OE1311/OE1351 can be set from 1 μs to 3 ks. The roll-off rate of the output low-pass filter can be set to 6, 12, 18, 24, 30, 36, 42, and 48 dB/oct. This low-pass digital filter is implemented using an infinite impulse response (IIR) filter structure, and its signal processing is performed at a sampling rate of 4 MHz. the digital modulation method and the filter structure used in the OE1311/OE1351 ensure a higher performance relative to an analog The digital modulation method and filter structure used in the OE1311/OE1351 ensure higher dynamic reserve (>120 dB), precise phase (absolute phase error <1°), zero DC drift and good quadrature compared to analog lock-in amplifiers. In addition, the OE1311/OE1351 uses a synchronization filter to eliminate the harmonic effects of the reference signal when the frequency of the input signal is lower than 1 kHz, ensuring that the instrument can quickly detect valid low-frequency signals.

Oscilloscope

The oscilloscope features a 4 MSa/s analog input channel with 2 MHz analog bandwidth, 5 Vrms input voltage range, and user-configurable AC/DC coupling and 10 MΩ impedance.

Spectrum Analyzer

        Spectrum analyzers can observe DC to 2 MHz input signals in the frequency domain. Simultaneous resolution bandwidths are as low as 1 Hz with a minimum span of 100 Hz.

Multi-Demodulator

Conventional lock-in amplifiers can only measure the fundamental frequency or a certain harmonic component at the same time. Therefore, for some cases that require the amplitude and phase of multiple frequency components at the same time, traditional lock-in amplifiers are unable to meet the measurement requirements.The digital side of the OE1311/OE1351 combines FPGA and ARM technology to realize higher processing bandwidth and more flexible digital architecture, with a digital processing accuracy of up to 48 bits, allowing up to 8 easy frequency analysis signal inputs at the same time, and 8 demodulators that can be freely configured for amplitude and phase to realize free combination. demodulators can be freely configured amplitude and phase to realize free combination. 

Signal Generator

Based on a 16-bit digital-to-analog converter (DAC), the OE1311/OE1351 is capable of generating sinusoidal signals in the frequency range of 1 uHz to 100/500 kHz, whose amplitude and phase are related to the instrument's internal oscillator, and the amplitude of the sinusoidal signals generated can be set via the instrument's control catalog. The OE1311/OE1351 generators can generate sine wave signals with a maximum amplitude of 5 Vrms.

Interfaces

The interfaces of the OE1311/OE1351 are standardized to 1000 Mbps RJ45 Ethernet and XH 2.54-4 PIN serial ports. Through the network port or serial port, the user can effectively use all the test functions of the OE1311/OE1351 on the control computer, including setting the instrument's proper control parameters and reading the data measured by the instrument.

PC Software Operation

Equipped with graphical upper computer software. With quick graphic buttons and rich graphic operation functions, in addition, the software has a clear numerical value display and waveform display function, real-time display of measurement data, measurement results can be saved in excel format output for subsequent analysis of professional software, so as to make the test easy to handle. In addition, we also fully support Python, MATLAB and LabVIEW application program interface (API).