- Signal Generator Definition: A signal generator is defined as a device that produces electronic signals and waveforms for testing and designing electronic equipment.
- Function Generators: Function generators create basic waveforms like sine and square waves using electronic oscillators.
- Arbitrary Waveform Generators: These generators produce complex, user-defined waveforms for specialized testing.
- RF Signal Generators: RF signal generators generate radio frequencies using phase-locked loops for stable signal output.
- Block Diagram of Signal Generator: The block diagram of a signal generator illustrates the components and flow of signals within the device, showing how it produces and modulates different waveforms.
What is a Signal Generator?
Signal generators provide controlled electrical stimuli for design, verification, repair and troubleshooting. Depending on the instrument, the output may be periodic, pulsed, modulated, patterned or an arbitrary stored waveform. Typical settings include frequency, amplitude, DC offset, phase, duty cycle, sweep, burst and modulation. A generator supplies the stimulus; an oscilloscope, spectrum analyser or other instrument measures the device under test. Frequency range, output impedance, fidelity, timing and load limits must match the test.
Types of Signal Generators
Function Generators
A function generator produces standard repetitive waveforms such as sine, square, triangle, ramp and pulse. Older designs may shape the output of an analogue oscillator; many current instruments use direct digital synthesis and a digital-to-analogue converter. Frequency, amplitude, offset and often modulation or burst controls are provided.
Function generators are available as bench instruments, USB modules and integrated test-system sources. Software can control the hardware, but software alone cannot drive a physical device under test without a suitable output interface.
Arbitrary Waveform Generators
An arbitrary waveform generator reads user-defined sample values from waveform memory, clocks them through one or more digital-to-analogue converters and conditions the resulting output. It can reproduce captured signals, sensor profiles, communication waveforms or deliberate impairments. Channel count, display, bandwidth, sample rate, vertical resolution and memory depth depend on the model. AWGs support semiconductor, communications, component and system tests that need a waveform beyond a preset function list.
RF Signal Generators
Radio frequency (RF) signal generators produce a controlled carrier over a specified RF or microwave range. Frequency synthesis may use phase-locked loops, direct digital synthesis, direct analogue synthesis or combinations of these methods. Important specifications include phase noise, frequency accuracy, output level accuracy, harmonics, spurious signals and switching speed. Output may be unmodulated or modulated. The modulation architecture may be analogue or vector, depending on the receiver, component, radar or communications test.
Analogue RF Signal Generators
An analogue RF generator supplies a continuous-wave carrier and may add AM, FM or phase modulation. Modern signal generators often use synthesised frequency control and digital electronics internally, but the term analogue still describes the modulation capability. These sources remain useful when a test does not require digitally modulated I/Q waveforms.
Vector Signal Generators
Vector signal generators, also called digital signal generators in some product literature, create RF carriers with controlled in-phase and quadrature components. This supports digitally modulated formats such as QPSK, QAM and OFDM, as well as user-defined baseband waveforms and channel impairments.
Logic Signal Generators
Logical signal generators produce pulses or defined bit patterns at specified logic voltage levels. A pulse generator focuses on width, repetition rate, delay and edge timing. A pattern generator outputs programmed data sequences, often across several synchronised channels. These sources support interface validation and timing margin tests. They also stimulate digital devices with repeatable data.
Audio Signal Generators
Audio signal generators provide low-distortion tones and sweeps over the audio band, commonly 20 Hz to 20 kHz and often beyond. They stimulate amplifiers, filters, transducers and recording equipment for frequency-response, noise and distortion tests. Measuring distortion also requires an analyser with a noise floor and residual distortion below the expected result. A music synthesiser is a creative sound source, not simply another name for a laboratory audio generator.
Video Signal Generators
A video signal generator produces known test patterns, timing and interface signals for displays, receivers and video paths. Analogue systems use horizontal and vertical synchronisation, while digital interfaces use format-specific pixel clocks, framing and encoded data. Resolution, frame rate, colour format, interface standard and compliance options must match the equipment under test.
