Have you ever wondered what happens inside your audio equipment? How does the audio data on a CD, MP3, or WAV file go from digital to sound? Much of this “magic” is thanks to the digital-to-analog converter (DAC). The job of a DAC is to convert digital data into an analog audio signal. This analog signal is then passed to an amplifier. The digital recording you hear is actually the result of the DAC converting the digital signal into an analog signal. Types: Sigma-Delta ADC Sigma-Delta ADC (or Σ-Δ ADC) is a high-precision analog-to-digital converter that converts analog signals into digital signals through specific techniques. Its working principle can be simplified into the following steps: 1. Sampling and quantization: The Σ-Δ ADC first uses a high-speed sampling circuit to frequently sample the analog signal. This process is completed by a component called a “Σ-Δ modulator”. The modulator oversamples the analog signal, that is, it samples at a rate much higher than the target signal frequency. 2. Σ-Δ modulation: In the modulator, the analog signal passes through an integrator and a comparator. The function of the integrator is to integrate the difference of the input signal to form a slower changing signal. The comparator compares this signal with a reference level and outputs a high-frequency pulse sequence. This pulse sequence contains the information of the input signal. 3. Noise shaping: The key feature of Σ-Δ modulation is noise shaping, which pushes the quantization noise to the high-frequency region, so that the noise is greatly reduced in the low-frequency signal range of interest. This helps to improve the effective resolution of the converter. 4. Digital filtering: The high-frequency pulse train output by the modulator passes through a digital filter, which converts the pulse train into the final digital output value. This process is called “noise shaping”, which extracts useful signal components and further reduces noise. 5. Downsampling: The digitally filtered signal is downsampled to the required sampling rate to form the final digital output. Σ-Δ analog-to-digital converters are widely used in high-precision audio recording, measurement systems, and high-fidelity audio equipment due to their high resolution and excellent noise performance. It is designed to effectively process low-frequency signals while reducing the interference of high-frequency noise. SAR Analog-to-Digital Converters SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a commonly used analog-to-digital converter that converts analog signals into digital signals. The working principle of SAR ADC can be divided into the following steps: 1. Sampling: SAR ADC first samples the analog input signal and holds the voltage value of the signal. At this stage, the input signal is kept stable by the sample-and-hold circuit for the subsequent conversion process. 2. Successive approximation: SAR ADC uses a successive approximation register (SAR) to estimate the digital value of the input signal. SAR is a digital circuit that approximates the actual value of the input signal through a series of comparison operations. 3. Comparison operation Initialization: SAR ADC first sets the digital register to the middle value (usually the highest bit is set to 1 and the other bits are set to 0), which is the initial estimate. Bit-by-bit approximation: Starting from the highest bit, SAR ADC converts the current digital estimate into an analog signal and compares it with the input signal. If the analog signal is higher than the current estimate, the SAR adjusts the estimate; if the analog signal is lower than the current estimate, the SAR keeps the estimate unchanged. This process gradually approaches the highest bit to the lowest bit, gradually determining the value of each bit. 4. Output: After a series of comparison operations, the SAR ADC finally generates a digital value that corresponds to the analog voltage of the input signal. This converter is widely used in various digitization and measurement systems due to its accuracy and efficiency. Isolated ADC An Isolated ADC (isolated analog-to-digital converter) is an analog-to-digital converter that provides electrical isolation between the analog input signal and the digital output. The purpose of isolation is to protect the device and measurement system from electrical interference, ground loops, and high voltages. Isolation prevents these factors from damaging the normal operation of the device or causing data errors. The following are the main features of Isolated ADC: 1.Isolation voltage: Isolated ADC can provide high voltage isolation, usually in the range of several kilovolts (kV). In this way, it can effectively isolate the analog signal input section from the digital signal output section, protecting the system from high voltage or ground potential differences. 2.Prevention of ground loop current: Isolation can eliminate ground loop currents caused by different ground potentials, which helps to improve the accuracy and reliability of measurements. 3.Isolation technology: Isolated ADC uses different isolation technologies such as optocouplers (optical isolators), transformer isolation, or capacitive coupling to separate the isolated part of the analog signal from the digital signal processing part. These technologies ensure that the signal is accurately transmitted without interference. 3.Overvoltage protection: In high voltage environments, Isolated ADC can protect other sensitive electronic equipment from overvoltage. 4.System stability: Isolation improves overall system stability and data reliability by eliminating sources of interference and ground potential differences. Audio ADC An Audio ADC (Audio Analog-to-Digital Converter) is an analog-to-digital converter specifically designed to convert analog audio signals into digital signals. It plays a key role in audio processing systems, converting sound signals into a digital format that can be processed by computers or digital devices. Here are some key features of Audio ADCs: 1. Sampling frequency: Audio ADCs typically support high sampling rates to capture the details of audio signals. Common sampling rates include 44.1 kHz (CD quality), 48 kHz (professional audio), 96 kHz, and 192 kHz (high-resolution audio). 2. Bit depth: Audio ADCs offer high bit depths to increase the dynamic range and resolution of audio signals. Common bit depths are 16 bits (CD quality), 24 bits (professional audio), and 32 bits (high dynamic range audio). 3. Signal-to-noise ratio (SNR): Audio ADCs are designed with a focus on low