A brief discussion on signal source classification and selection considerations

Signal generator, also known as signal source or oscillator, is an instrument used to generate various electronic signals. It is one of the instruments commonly used by electronic engineers. Today, Antai Test will share with you the classification and selection considerations of signal generators:

1. Signal generators are classified by waveform

Sine signal generator

Function signal generator

Sweep signal generator

Pulse and digital signal generator

Modulation signal generator

Noise and Pseudo-Random Signal Generators

Arbitrary Waveform Generator

2. Signal generators are classified by fundamental frequency

Ultra low frequency signal source 0.0001~1000Hz

Low frequency signal source 1Hz~200KHz

Video signal source 10Hz~10MHz

High frequency signal source 200KHz~30MHz

VHF signal source 30~300MHz

Ultra-high signal source 300MHz or above

3. Main indicators and precautions for signal generator selection:

1. Bandwidth: The bandwidth of a signal source is the maximum frequency of a sine wave that the signal source can output. For example, a 250MHz signal source means that its maximum sine wave output frequency can reach 250MHz.

2. Number of channels: The number of channels that the signal source can output signals at the same time when using the signal source. Currently, the channels of the signal source are divided into analog waveform output channels and digital waveform output channels. The configurations of different signal source manufacturers vary greatly.

3. Sampling rate: The speed at which the signal source takes points from the memory when outputting the waveform is the sampling rate of the signal source. The higher the sampling rate, the higher the degree of waveform restoration.

4. Vertical resolution: In mixed signal generators, vertical resolution is related to the binary word length (in bits) of the instrument DAC, with more bits resulting in higher resolution. The vertical resolution of the DAC determines the amplitude accuracy and distortion of the reproduced waveform. A DAC with insufficient resolution can result in quantization errors, leading to suboptimal waveform generation. Although higher is better, in AWGs, higher frequency instruments (8 or 10 bits) typically have lower resolution than general purpose instruments with 12 or 14 bits.

5. Output signal amplitude: The output amplitude of the signal source needs to be selected according to the amplitude range used by the experimenter. For example, the signals required by audio R&D engineers are mostly large drive signals of 10~100V, while the bioelectric waves concerned by medical device R&D engineers are concentrated in the uV~mV range.

6. Editable length of arbitrary wave: Today's signal sources are generally called function/arbitrary wave signal sources. Arbitrary wave refers to a waveform that can be edited arbitrarily according to the user's requirements. The waveform length is the number of points used to describe the waveform you created. The more points described, the more realistic the restored waveform is. For example: Today's oscilloscopes can save the collected field data waveforms, and then reproduce them with signal sources in the laboratory. If the storage depth of the oscilloscope is 1Mpts, the arbitrary wave length of the signal source must be no less than 1Mpts to perfectly reproduce the signal.

7. Phase noise: Phase noise refers to the ratio of noise density per unit Hz to the total signal power. It manifests itself as a random drift of the carrier phase and is an important indicator for evaluating the spectral purity of a frequency source (oscillator).

Selection considerations:

The signal source is generally used as an excitation signal source, and its power driving capability is very small (mW level). Therefore, if you need to use the signal source to drive the subsequent load (such as speakers, motors), you need to install a power amplifier or choose a power signal source.