Signal generators: does analog or digital make a difference?

• Frequency range: this is essential for determining the scope of tasks your signal generator can handle, encompassing both low- and high-frequency applications. A wider frequency range allows the instrument generator to be used in various applications, making it more versatile.  

• Amplitude range: a broader amplitude range enhances versatility and precision, enabling the generator to meet specific requirements of different applications and ensureaccurate and reliable test results. 

• Modulation capabilities: to accurately simulate real-world scenarios, signal generators must accommodate various modulation techniques, from AM and FM to more sophisticated digital modulations. 

• Output power: sufficient and adjustable output power allows you to operate the system or circuit at different levels, which is crucial for stress tests and other assessments. 

• Resolution: greater resolution leads to more precise test outcomes, enabling you to analyse and comprehendthe system or circuit in detail. 

• Waveform format: different applications require specific waveform types, such as sine, square, and triangle waves, so it’svital to ensure the generator can create the signal formats for accurate testing.
  

Analog signal generators

Analog signal generators provide sinusoidal continuous wave (CW) signals with optional capabilities for AM, FM, phase modulation (M), and pulse modulation. The frequency range extends from RF to mmWave. Most generators include step/list sweep modes for characterising or calibrating passive devices. These generators deliver metrology-grade frequency and level accuracy, making them essential for high-precision tasks.

Analog signal generators are crucial in Doppler radar testing under real-world conditions. The low phase noise characteristics make them ideal for high signal purity and stability applications, such as radar systems for weather forecasting and air traffic control. In these environments, any deviation or noise can lead to inaccurate data.

Digital signal generators

Unlike waveform, digital signal generators produce sequences of logic levels or digital patterns. These patterns are essential for evaluating the logic and timing of digital circuits and their performance under various conditions.

Typical applications:

• System-level testing: ensures that complex digital systems function as intended, verifying inter-component compatibility
• IC testing: assesses individual integrated circuits, identifying manufacturing defects or design flaws
• Debugging: assists engineers in troubleshooting problematic circuits, focusing on issues related to timing or logic

In the automotive industry, digital pattern generators are vital for ensuring the reliability of electronic control units (ECUs), which manage everything from engine performance to safety systems. By simulating driving conditions with pre-defined digital patterns,  engineers can test ECUs under diverse scenarios. This helps identify faults or vulnerabilities, ensuring the vehicle’s systems operate flawlessly, even under extreme conditions.

Different applications

There are various options for analog and digital signal generators, from RF to vector or function, so engineers must focus on the end goal to select the best solution.

General-purpose testing: a signal generator with a broad frequency range and high output power is best for general-purpose testing. Additionally, modulation capabilities such as amplitude, frequency, sweep, and burst should be considered when testing periodic signals

Telecommunications applications: an extensive frequency range and a low-noise floor is essential for telecom munications applications. This ensures accurate testing and the generation of signals with minimal interference. It is also important to consider complex modulation formats used in telecom munications, such as frequency-shift keying (FSK) and phase modulation (PM)

Audio and video equipment: low distortion levels are crucial for testing audio and video equipment as they guarantee that the generated signal is high-quality and free from distortion. Additionally, modulation capabilities such as amplitude-shift keying (ASK), frequency-shift keying, pulse code modulation (PCM), and quadrature modulation (QM) should be considered

Automotive testing: vehicle electronics operate in harsh environments, requiring a wide frequency range and high output power. Therefore, the generator must produce accurate and reliable signals

Selecting the right signal generator

Accurate and reliable testing is crucial for ensuring the quality and performance of designs. With the overwhelming number of signal generators on the market, finding the right one can take time. While the distinction between analog and digital generators might seem significant, the true differentiators are the features and their alignment with project requirements.

Analog signal generators are ideal for applications requiring high signal purity and low phase noise, such as RF and microwave testing. For modern communication systems and advanced research, digital signal generators are better as they provide greater flexibility and precision to generate complex waveforms. Choosing the wrong solution can lead to costly and time-consuming rework. So, it’s critical to select the right signal generator to get the data needed to refine and enhance designs.