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In stock
GW Instek AFG-2125 25 MHz Arbitrary Function Generator with Modulation, Sweep, and Counter
Key Features At A Glance
- Frequency range from 0.1 Hz to 5 MHz, 12 MHz, or 25 MHz across the series with 0.1 Hz resolution
- Sine, Square, Ramp, Noise, and Arbitrary waveforms with 20 MSa/s sampling rate, 10-bit vertical resolution, and 4k point memory
- 1% to 99% adjustable duty cycle for square waveform (resolution and range vary by frequency per datasheet)
- 3.5-inch LCD displays amplitude, DC offset, and key setting information simultaneously
- AM/FM/FSK modulation, Sweep, and 150 MHz Frequency Counter available on AFG-2100 models (not on AFG-2000 models)
- USB device interface for remote control and arbitrary waveform editing via free FreeWave PC software
- 10 groups of setting memories for storing and recalling instrument configurations
View full details
The Instek AFG-2125 is part of the AFG-2000/2100 Series of DDS-based arbitrary function generators that cover Sine, Square, Ramp, Noise, and Arbitrary waveform output. The series spans six models across three frequency bands — 5 MHz, 12 MHz, and 25 MHz — with the AFG-2125 occupying the top 25 MHz tier within the AFG-2100 family that adds modulation and counter capability beyond the base AFG-2000 line.
A function generator creates known, controlled test signals — sine, square, triangle, ramp, and pulse waveforms — that engineers use to stimulate a device under test so that its response can be measured. The arbitrary waveform capability extends this further by allowing user-defined waveform shapes to be generated, which is useful for replicating real-world signal profiles. The AFG-2000/2100 datasheet lists applications including audio products frequency characteristics measurement, pulse signal as trigger or synchronization signal for electronic product testing, reference clock signal generation, vibration signal simulation, and noise simulation for communication system educational labs.
ValueTronics International has supplied new and pre-owned test and measurement instruments since 1992 from our 20,000 sq ft secure warehouse at 1675 Cambridge Drive, Elgin, Illinois. Every instrument is inspected and performance-verified by our technical team before it ships, and we maintain the inventory depth and documentation resources that drop-shippers and pass-through brokers cannot match. When you order an AFG-2125 from ValueTronics, you are working directly with the people who handled the unit — not a marketplace listing.
Compare Other Models in This Series
The AFG-2000/2100 Series comprises six DDS-based arbitrary function generators organized across three maximum frequency tiers — 5 MHz, 12 MHz, and 25 MHz — and two feature levels. The AFG-2000 base line provides the core sine, square, ramp, noise, and arbitrary waveform generation capability. The AFG-2100 line adds AM/FM/FSK modulation, sweep functionality, and a built-in 150 MHz frequency counter on top of the same waveform generation foundation.
All six models share the same 20 MSa/s arbitrary sampling rate, 10-bit amplitude resolution, 4k point arbitrary memory, 0.1 Hz frequency resolution, 1% to 99% adjustable square wave duty cycle, USB device interface, and 3.5-inch LCD display. The differentiation across the series is primarily maximum frequency for sine and square output and the presence or absence of the AFG-2100 modulation, sweep, and counter feature set.
Each model in the AFG-2000/2100 Series is listed as its own product page on valuetronics.com with condition-matched new pricing. Use the comparison table below to identify which combination of frequency tier and feature set fits your application, then visit the individual product page for that model to see current availability and ordering details.
Within the family, the AFG-2125 is the top-frequency model in the AFG-2100 feature line, combining the 25 MHz sine/square maximum with the modulation, sweep, and 150 MHz counter capability that the AFG-2000 base models do not include.
The three AFG-2000 models (AFG-2005, AFG-2012, AFG-2025) and three AFG-2100 models (AFG-2105, AFG-2112, AFG-2125) differ in maximum sine and square output frequency at 5 MHz, 12 MHz, and 25 MHz respectively. Maximum amplitude into 50 ohms is 10 Vpp on the 5 MHz and 12 MHz models and 5 Vpp on the 25 MHz models per the datasheet. Amplitude flatness specifications also vary across the frequency tiers.
The AFG-2100 line adds AM/FM/FSK modulation (sine, square, and triangle carriers with 2 mHz to 20 kHz internal modulating frequency), sweep (linear or logarithmic, 1 ms to 500 s sweep time), and a 5 Hz to 150 MHz frequency counter with 35 mVrms sensitivity from 5 Hz to 100 MHz. The AFG-2000 line does not include these functions. Review the comparison table for the headline specifications side by side.
| Model |
Max Frequency |
Modulation/Sweep/Counter |
Sample Rate |
| AFG-2125 |
25 MHz |
Yes (AM/FM/FSK, Sweep, 150 MHz Counter) |
20 MSa/s |
| AFG-2105 |
5 MHz |
Yes (AM/FM/FSK, Sweep, 150 MHz Counter) |
20 MSa/s |
| AFG-2112 |
12 MHz |
Yes (AM/FM/FSK, Sweep, 150 MHz Counter) |
20 MSa/s |
| AFG-2005 |
5 MHz |
No |
20 MSa/s |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
Accessories Supplied
- GTL-110 × 2
- Instruction Manual × 1
- Power cord × 1
Product Core & Specifications
| Category |
Parameter |
AFG-2105 |
AFG-2112 |
AFG-2125 |
AFG-2005 |
AFG-2012 |
AFG-2025 |
| Waveforms / Arbitrary Function |
Waveforms |
Sine, Square, Ramp |
| Sample Rate |
20 MSa/s |
| Repetition Rate |
10 MHz |
| Waveform Length / Amplitude Resolution |
4k point / 10 bit |
| Frequency Characteristics |
Range Sine / Square |
0.1 Hz–5 MHz |
0.1 Hz–12 MHz |
0.1 Hz–25 MHz |
0.1 Hz–5 MHz |
0.1 Hz–12 MHz |
0.1 Hz–25 MHz |
| Range Triangle, Ramp |
1 MHz |
| Frequency (cont.) |
Resolution |
0.1 Hz |
| Stability |
±20 ppm |
| Aging |
±1 ppm, per 1 year |
| Tolerance |
<10 mHz |
| Output Characteristics |
Amplitude Range |
≤20 MHz: 1mVpp–10Vpp (into 50Ω); 2mVpp–20Vpp (open-circuit)
≤25 MHz: 1mVpp–5Vpp (into 50Ω); 2mVpp–10Vpp (open-circuit) |
≤20 MHz: 1mVpp–10Vpp (into 50Ω); 2mVpp–20Vpp (open-circuit)
≤25 MHz: 1mVpp–5Vpp (into 50Ω); 2mVpp–10Vpp (open-circuit) |
| Amplitude Accuracy |
±1% of setting ±1 mVpp; (at 1 kHz, >10 mVpp) |
| Amplitude Resolution |
0.1 mV or 3 digits |
| Flatness |
±1% (0.1 dB) ≤100 kHz; ±3% (0.3 dB) ≤5 MHz; ±5% (0.4 dB) ≤12 MHz; ±20% (2dB) ≤20 MHz; ±5% (0.4 dB) ≤25 MHz (sine wave relative to 1 kHz) |
| Units |
Vpp, Vrms, dBm |
| Offset Range |
±5 Vpk ac + dc (into 50Ω); ±10 Vpk ac + dc (Open circuit) |
| Offset Accuracy |
1% of setting + 2 mV + 0.5% of amplitude |
| Waveform Output Impedance / Protection |
50Ω typical (fixed); >10MΩ (output disabled). Short-circuit protected; overload relay automatically disables main output |
| SYNC Output |
TTL-compatible into >1kΩ; 50Ω nominal; Rise or Fall Time ≤25 ns |
| Sinewave |
Harmonic Distortion |
-55 dBc, DC~1 MHz, Ampl >1 Vpp; -45 dBc, 1 MHz~5 MHz, Ampl >1 Vpp; -30 dBc, 5 MHz~20 MHz, Ampl >1 Vpp |
| Squarewave |
Rise/Fall Time |
≤25 ns at maximum output (into 50Ω load) |
| Overshoot |
<5% |
| Asymmetry |
1% of period + 1 ns |
| Variable Duty Cycle |
1%~99% 100 kHz; 10%~90% 2 MHz; 20.0%~80.0% 5 MHz; 40.0%~60.0% 10 MHz; 50% 25 MHz; (1% Resolution for full Frequency Range) |
| Ramp |
Linearity |
<0.1% of peak output |
| Variable Symmetry |
0%~100% (0.1% Resolution) |
| AM Modulation (AFG-2100 only) |
Carrier Waveforms |
Sine, Square, Triangle |
— |
| Modulating Waveforms |
Sine, Square, Triangle |
— |
| Modulating Frequency |
2 mHz to 20 kHz (Int); DC to 20 kHz (Ext) |
— |
| Depth |
0% to 120.0% |
— |
| FM Modulation (AFG-2100 only) |
Carrier Waveforms |
Sine, Square, Triangle |
— |
| Modulating Waveforms |
Sine, Square, Triangle |
— |
| Modulating Frequency |
2 mHz to 20 kHz (Int); DC to 20 kHz (Ext) |
— |
| Deviation |
DC to Max Frequency |
— |
| FSK (AFG-2100 only) |
Sweep Time |
1 ms~500 s |
— |
| Carrier Waveforms |
Sine, Square, Triangle |
— |
| Modulating Waveforms |
50% duty cycle square |
— |
| Internal Rate |
2 mHz~20 kHz |
— |
| Frequency Range |
0.1 Hz~Max Frequency |
— |
| Sweep (AFG-2100 only) |
Waveforms |
Sine, Square, Triangle |
— |
| Type |
Linear or Logarithmic |
— |
| Start/Stop Frequency |
0.1 Hz to Max Frequency |
— |
| Frequency Counter (AFG-2100 only) |
Range |
5 Hz~150 MHz |
— |
| Accuracy |
Time Base accuracy ±1 count |
— |
| Time base |
±20 ppm (23°C ± 5°C) after 30 minutes warm up |
— |
| Resolution |
The maximum resolution is: 100 nHz for 1 Hz, 0.1 Hz for 100 MHz |
— |
| Input Impedance / Sensitivity |
1 MΩ/150 pF; 35 mVrms (5 Hz~100 MHz); 45 mVrms (100 MHz~150 MHz) |
— |
| Store/Recall |
Memories |
10 Groups of Setting Memories |
| Interface |
USB |
USB (Device) |
| Power Source |
AC Input |
AC 100–240 V, 50–60 Hz |
| Power Consumption |
— |
65 VA |
| Dimensions & Weight |
W × H × D; Weight |
266 (W) × 107 (H) × 293 (D) mm; Approx. 3.2 kg |
266 (W) × 107 (H) × 293 (D) mm; Approx. 3.1 kg |
Important: Maximum output amplitude on the AFG-2125 is 5 Vpp into 50 ohms (10 Vpp open-circuit). Maximum offset is ±5 Vpk AC+DC into 50 ohms (±10 Vpk open-circuit).
Important: AM/FM/FSK Modulation, Sweep, and Frequency Counter functions are available on AFG-2100 Series models (AFG-2105, AFG-2112, AFG-2125) only; the AFG-2000 Series models (AFG-2005, AFG-2012, AFG-2025) do not include these