Quick Answer
Signal generator calibration at Prism verifies: output frequency accuracy (using calibrated frequency counter), amplitude accuracy (using calibrated True RMS voltmeter), waveform distortion (THD using audio analyser), DC offset accuracy, and frequency range coverage from the instrument's minimum to maximum rated frequency.
Key Takeaways
- Signal generator calibration covers: frequency accuracy, amplitude, DC offset, distortion (THD).
- Reference: Keysight 53230A frequency counter (OCXO-based, < 1 ppm accuracy).
- Calibration frequency range: 0.01 Hz to rated maximum (typically 1–50 MHz for function generators).
- Amplitude calibrated at 50 Ω and 1 MΩ output impedance settings.
- Prism calibrates Keysight 33xxx, Rigol DG series, Tektronix AFG, Fluke PM5138 generators.
Signal Generator Parameters Calibrated
- Frequency accuracy (using NABL-calibrated frequency counter)
- Sine wave amplitude accuracy at 50 Ω (from 0.1 Vpp to maximum rated)
- DC offset accuracy (±max offset voltage)
- Total harmonic distortion (THD) of sine wave output
- Square wave duty cycle and rise/fall time
- DC voltage output accuracy (for generators with DC output)
Frequently Asked Questions
How accurate is signal generator frequency output?
Most function generators use a TCXO or OCXO crystal reference with accuracy of ±10–50 ppm. Calibration verifies the actual frequency accuracy against a NABL-calibrated frequency counter (< 1 ppm reference). For applications requiring < 1 ppm frequency accuracy, GPS-disciplined signal generators are recommended.
Does Prism calibrate RF signal generators?
Prism calibrates RF signal generators up to 3 GHz for amplitude accuracy and frequency accuracy. For RF generators requiring power level calibration in dBm, a calibrated power meter and power sensor are used.
How often should signal generators be calibrated?
Annual calibration is standard. Signal generators used as references in production test systems or calibration setups should be calibrated every 6 months.
What is THD for a signal generator and why does it matter?
THD (Total Harmonic Distortion) measures the purity of the sine wave output. For a 1 kHz sine wave, THD < 0.1% is typical for quality generators. High THD causes errors when testing circuits or calibrating amplifiers — the reference 'sine wave' contains unwanted harmonics.
Can Prism calibrate arbitrary waveform generators (AWGs)?
Yes. AWG calibration covers the same parameters as function generator calibration. Waveform fidelity and DAC linearity can also be assessed.
Written by
Er. Parthiv Kinariwala
Managing Director · Prism Calibration Centre · NABL CC-2480 · Ahmedabad
Er. Parthiv Kinariwala founded Prism Calibration Centre in 2004 and has over 20 years of hands-on experience in calibration engineering, NABL accreditation, and industrial compliance. His team performs 10,000+ calibrations annually from the Vatva GIDC laboratory, serving 5000+ industries across Gujarat.
Prism Calibration Centre — Vatva GIDC, Ahmedabad
Prism Calibration Centre
F-101, Rudraksh Complex 2, Phase 3, GIDC Vatva, Near Jasoda Nagar Cross Road, Ahmedabad — 382445, Gujarat, India
Phone: +91 98245 26444
Email: info@prismcalibration.com
NABL: CC-2480 · ISO/IEC 17025:2017
Hours: Mon–Sat, 9:00 AM – 7:00 PM