Impedance measuring instrument DXA-205

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Overview:

The DXA-205 is a high-performance digital lock-in amplifier covering DC to 1.5 MHz for precision synchronous detection and measurement. It integrates multi-channel demodulation, low-noise inputs, oscilloscope and FFT analysis, parametric scanning and dual-channel PID controllers for closed-loop control, enabling advanced measurement and control workflows in research and industrial test setups.

Applications:

• Scanning microscopy: AFM, STM, SPM
• Materials science: carrier mobility, carrier density, Hall effect, ultrasonic materials
• Transport measurement: conductivity and impedance characterization
• Noise analysis: noise density and cross-correlation measurements
• Optical experiments: spectral analysis, THz and TDLAS measurements
• Sensor evaluation: gyroscopes, photoelectric sensors, resonators, accelerometers
• Magnetic sensing: SQUIDs, NV centers, atomic magnetometers, VSM
• Biomedical: microfluidic and bioinstrumentation measurements

Key features and functions:

• Frequency coverage DC to 1.5 MHz with high accuracy and ultra-fine resolution
• Extremely low input noise (down to 2.5 nV/√Hz) and wide sensitivity range (1 nV to 5 Vrms)
• Eight synchronous demodulators for parallel measurements and >130 dB dynamic reserve
• Built-in 2-channel oscilloscope and FFT analyzer; oscilloscope supports up to 65,536 sample depth and adjustable sampling time (65 μs–1 s)
• Internal dual independent digital PID controllers with up to 4 MSPS sampling, tightly integrated with demodulators
• Parametric scanner for rapid frequency/amplitude plotting with single or cyclic scan modes
• Multiple communication interfaces: RS-232, USB2.0, Gigabit Ethernet, Wi‑Fi and GPIB (IEEE-488.2)

Technical specifications:

• Input channel — modes: Voltage (single-ended or differential) or Current (single-ended)
• Full-scale sensitivity: 1 nV to 5 Vrms
• Range levels: 2 mV to 5 V (7 total levels)
• Input coupling: DC or AC
• Input impedance (voltage): 10 MΩ || 25 pF; (current): 100 Ω or 1 kΩ
• Input shield grounding: grounding or 10 kΩ floating
• Dynamic reserve: >130 dB
• Gain accuracy: 0.5% typical, 1% max
• Input voltage noise: 3.5 nV/√Hz (f ≥ 1 kHz); 2.5 nV/√Hz (f ≥ 10 kHz)
• Input current noise: 20 fA/√Hz (f = 97 Hz)
• ADC (input): 24 bit
• Output channel — frequency range: DC – 1.5 MHz
• Frequency accuracy: 2 ppm + 1 μHz; frequency resolution: 1 nHz
• Sine amplitude (output): 0.1 μVrms to 5 Vrms; accuracy 0.5% typical, 2% max; resolution 0.1 μVrms
• Driving current: ±80 mA max; output impedance: 50 Ω
• Adjustable DC offset: -5 VDC to 5 VDC
• Synchronous output: 3.3 V TTL/CMOS level (output impedance 50 Ω)
• Additional output: AM/FM/PM modulation; DAC: 16 bit, 32 MSPS
• Reference channel — 2 channels; frequency range: 10 μHz – 1.5 MHz; supported waveforms: square or sine; input impedance: 1 MΩ
• Reference levels: Square: 3 V < VIH < 5 V, -0.1 V < VIL < 0.5 V; Sine: >1 Hz; 300 mV < Vpp < 10 V
• Phase: resolution 1.0 μdeg; phase error ±0.5° typical, ±1° max; temperature drift < 200 ppm/°C
• Harmonic detection: 1–10000F (nF < 1.5 MHz)
• Acquisition time: internal reference instantaneous; external reference: 10 or 100 signal cycles
• Oscillators: 2; accuracy 0.3 ppm; temperature stability 0.5 ppm/°C; aging <1 ppm/year; phase noise -145 dBc/Hz (@1 kHz)
• Demodulators: 8 channels; 64-bit processing
• Time constant: 100 ns – 3 ks; measurement bandwidth: 50 μHz – 1.6 MHz
• Filter slopes (dB/oct): 6, 12, 18, 24, 30, 36, 42, 48; synchronous filter effective below <1000 Hz
• Aux I/O — AUX input: 4-channel, ±10 V, 0.1 mV resolution, input impedance 1 MΩ, ADC 16 bit, 150 kSPS
• AUX output: 4-channel, ±10 V, 0.1 mV resolution, driving ±30 mA max, DAC 16 bit, 500 kSPS
• Interfaces: RS-232 (DB-9), USB 2.0 (480 Mbps), Ethernet RJ45 (1000 Mbps), Wi‑Fi, GPIB (IEEE-488.2)
• Power: 220–240 V AC (100–120 V optional); consumption 50 W typical, 70 W max; power noise suppression: 70 dB @ 1 MHz
• Dimensions: 448 mm × 532 mm × 148 mm; Weight: 12 kg
• Oscilloscope: 2 channels, selectable inputs (signal, reference, output, auxiliary), multiple triggers, max sample depth 65,536, adjustable sampling time 65 μs – 1 s
• PID controllers: 2-channel internal digital PID, up to 4 MSPS, integrated with lock-in measurements for closed-loop control of amplitude, phase and frequency
• Parametric scanner: instantaneous plotting of frequency/amplitude response; single or cyclic scan modes
• FFT analyzer: frequency-domain analysis from captured waveforms; resolution depends on sampling rate (approx. 1 Hz – 31 kHz)