µLIA-320 USB Dual-Phase Lock-In Amplifier

High performance in a compact, economical package...

The µLIA-320 USB Lock-In Amplifier (uLIA-320) accurately measures voltage signals in noisy environments. It returns analog-to-digital (x, y) samples of the demodulated signal through its USB 2.0 compliant interface.

Host-application Microsoft Windows software is included, with source code provided. The device-driver toolkit allows users to incorporate µLIA-320 functionality into their own Visual Studio applications.

The µLIA-320 is an economical alternative to high-end lock-in amplifiers, and specifically designed for multi-channel applications.


More information...  or call us at 541-550-5016

ullia-320 lock-in amplifier


  • Wavelength modulation and tunable diode laser absorption spectroscopy
  • Transmission and reflection characterization
    via optical-beam chopping
  • Laser-induced fluorescence detection
  • Rotating-analyzer spectroscopic ellipsometry
  • Near-field scanning optical microscopy
  • Undergraduate and graduate physical-science lab experiments

ullia-320 lock-in amplifier


  • Dual-phase signal recovery from 800 Hz to 400 kHz
  • Sensitivity ranges from 10 µV to 2 V: up to 63 dB of front-end AC gain
  • Streaming or single samples: continuous real-time streaming of demodulated (x, y) samples or readings-on-demand
  • Programmability: µLIA_dd device-driver toolkit permits integration of µLIA-320 capabilities into user-supplied applications
  • Native full-speed USB 2.0 compliant interface: multiple µLIA-320 instances on bus are supported--each µLIA-320 has a unique serial number for identication purposes.
  • DDS-based: the reference and (x, y) demodulator recovery channels are implemented with 32-bit Direct Digital Synthesis (DDS) technology
  • Reference channel can act as input or output
  • Software: µLIA-320 Panel application software with source code provided. Host USB drivers for Windows 7, Vista, and Windows XP.
  • Analog Monitor Output: software-selectable between four internal signals, permits standalone mode
  • Lightweight, miniature form-factor, with separate international power supply





Parameter Specification
Demodulator Characteristics
Signal input Bipolar voltage-only 0 to ±10V, 1MΩ/10 nF input impedance, AC-coupled
800 Hz to 410 kHz frequency range
AC gain 0 to 63 dB in discrete, calibrated 0-3-10 dB steps
AC overload Overload LED will illuminate for AC gains resulting in greater than ±10Vpeak into demodulator stages
Reference input Logic-level TTL-compatible signal, 800 Hz to 410 kHz, arbitrary duty cycle. Input signal is opto-isolated for reference input configuration
Reference output Logic-level TTL-compatible signal, calibrated frequencies 800 Hz to 410 kHz, 50% duty cycle
Reference configuration Conventional 1F quadrature: X and Y channels held 90° apart, phase-adjustable with respect to reference input or output. Phase adjustable to 0.1°
Monitor output Bipolar analog output
Software-selectable between four internal signal sources: AC-coupled signal input, AC gain stage output, X DC output, or Y DC output
X or Y demodulator outputs may be substituted for X or Y DC outputs by internal jumper selection
Demodulator type High bandwidth analog multiplier (homodyne)
Demodulator lowpass filter 4th-order Butterworth, 160 Hz cutoff frequency
DC gain 6 to 66 dB, set parametrically by chosen DC Sensitivity setting
Sensitivity 10 µV to 2V sensitivity ranges, in discrete, calibrated 1-2-5-10 steps
DC overload Overload LED will illuminate for AC & DC gain combinations resulting in greater than ±10V into either X or Y analog-to-digital stages
Time constants Time constants implemented by real-time digital filtering of acquired samples
1 ms to 50 ms in discrete steps
Gain accuracy ±0.5% typical end-to-end, ±1% maximum
A/D resolution Bipolar, 12 bits plus sign, referenced to 10.00 V
Host computer interface Full-speed USB 2.0 compliant, self-powered device; one interrupt and two bulk endpoints
Software uLIA-320 Panel application software (source code provided) permits instrument control and real-time acquisition of demodulated samples in (x, y) or (R, θ) formats
Host USB drivers for Windows 7, Vista, and Windows XP (executable only; 64-bit Windows XP not supported. Windows XP installation requires Service Pack 2 or higher)
Device drivers uLIA_dd device-driver toolkit (source code provided) for application programming in Visual Studio
Physical Characteristics
Dimensions 5.6 in W x 7.5 in L x 1.6 in H
Weight 1.4 lbs (µLIA-320)
2.9 lbs (µLIA-320 + power supply)
Chassis material Blue anodized aluminum, rubber bottom feet
Machined aluminum front & back panels, blue-anodized and laser etched
Front panel Power, Lock, and Overload LED’s
50-ohm BNC female bulkhead for Signal Input
50-ohm BNC female bulkhead for Monitor Output
Back panel DIN-5 female receptacle for power input
ON/OFF power switch
Series B USB receptacle for connection to host computer
50-ohm BNC female bulkhead for Reference Input/Output
RoHS & CE compliance 100% RoHS compliant; CE certification to FCC Class A emissions level upon special arrangement
Operating temperature 5 to 45 °C
Power supply Separate, supplied with µLIA-320
International +5V/+15V/-15V triple power supply, 42W, 100-240VAC 47-63Hz input, CE listed
DIN-5 male plug on 48 in cord
Warranty One year




1. What types of reference signals does the µLIA-320 accept?
The reference input accepts logic-level TTL-compatible signals of arbitrary duty cycle.
The reference input is opto-isolated from the rest of the instrument.

2. What is the lowest input reference frequency the µLIA–320 will accept?
The µLIA-320 accepts reference frequencies as low as 800 Hz. Many potential customers are interested in the ~1 kHz to 10 kHz frequency range, which the µLIA-320 handles well.

3. What is the minimum time constant available?
The minimum (“fastest”) time constant is 1 ms, and is determined by the bandwidth of the demodulator low-pass anti-aliasing filters. Selecting “0 ms” in µLIA-320 Panel or the µLIA_dd toolkit will return (x, y) samples with this inherent bandwidth only and no additional digital low-pass filtering.

4. What is the phase resolution of the µLIA–320?
The phase resolution or adjustability of the X and Y channels relative to the reference channel is 0.1 degrees. This value is determined by the bit-width of the Direct Digital Synthesis (DDS) phase-tuning registers. The µLIA-320 utilizes DDS’s with 12-bit phase-tuning registers, hence the underlying settability of the reference channel phase is one part in 4096.

5. Is the µLIA-320 an analog lock-in or a DSP lock-in?
The µLIA-320 is a modern digitally-controlled mixed-signal approach to an analog sine-wave multiplier lock-in amplifier. This recovery approach is similar to the Stanford Research SR510 and SR530 analog lock-ins. The front-end gain blocks, analog multipliers, and back-end demodulator low-pass filters are pure analog, and are designed to handle the full instrument bandwidth (400 kHz). These analog blocks do the 'heavy lifting' of the instrument, allowing the recovered quasi-DC baseband to be sampled at 1 ksample-pair/sec, digitally low-pass filtered, and (x, y) samples streamed over USB to the host PC.

6. Is there software provided that allows me to integrate the µLIA–320 into my existing application?
Yes. The µLIA_dd device-driver toolkit provides an API for the host/µLIA-320 message protocol for users that desire to tie the lock-in functionality into their own software. Source code & technical support for the uLIA_dd toolkit are included with the µLIA-320.

7. Does the µLIA-320 measure AC current?
Not directly. The µLIA-320 accepts bipolar voltage inputs in the ±10V range on the front-panel Signal Input BNC. This input is AC-coupled to a FET input amplifier. Current inputs must first be converted to the voltage domain by an appropriate transimpedance amplifier for the sensor

8. What is the highest frequency the µLIA–320 can recover?
The µLIA-320 can recover signals up to 400 kHz.

9. Can I use the µLIA–320 in standalone mode, without a PC?
Yes. The front-panel Monitor Output BNC outputs one of four internal analog signals. The µLIA-320 must first be configured by the host while attached to USB, and the X or Y DC output selected by software as the Monitor Output. When the µLIA-320 is detached from USB, the lock-in will hold its last-set configuration, and the selected X or Y signal will continue to appear on Monitor Output.

10. Does the µLIA–320 come with a display screen?
The µLIA-320 has a ‘virtual’ display screen through the µLIA-320 Panel program, on your desktop PC or laptop. This virtual front-panel is far more versatile and economical than any dedicated display screen we could provide.

11. Do you have any drivers/libraries that would allow me to control the µLIA-320 and collect data using a Raspberry Pi (Linux-like) or some other UNIX based operating system?
Not directly. The µLIA-320 ships with the uLIA_dd device-driver toolkit, which handles the details of the host/lock-in message protocol. This toolkit calls into the WinUSB and Registry interface module uLIAUsb.dll, which is specific to Microsoft Windows. Source code (standard C) is provided for the uLIA_dd toolkit, but not for the underlying .DLL. For a different operating environment than Windows (e.g. Raspberry Pi), there are a small number of USB API calls that would have to be implemented in order to port the µLIA_dd toolkit. Contact us for further details.

12. Is the µLIA–320 a USB bus-powered device?
No. The µLIA-320 has its own separate international power supply and thus draws negligible power from the USB bus.