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Analog-to-digital converters (ADCs) are the interface between the physical and digital worlds, converting real-world signals such as temperature, light, pressure, sound and voltage into digital data that CPUs, DSPs, FPGAs and AI hardware can process, analyze and store.

The importance of ADCs

The quality of the analog-to-digital conversion places a fundamental limit on how accurately a digital system can understand the physical world. Resolution, sampling speed, noise, linearity, power consumption and reference stability can all impact on system performance. This makes ADCs particularly challenging to design in modern mixed-signal integrated circuits (ICs). So how do chip design engineers achieve precise, predictable analog behavior in technologies increasingly optimized for digital computation?

Challenges with ADC design

When designing an ADC into a chip, there are some key challenges.

Digital noise and mixed-signal interference: Digital circuits switch at high frequencies billions of times per second and generate electrical noise through the power supply and substrate. Sensitive analog circuitry can pick up that noise. Therefore, chip design engineers often need to give careful consideration to floor planning, power distribution, grounding, shielding, substrate isolation and clock management.

Resolution versus speed: Higher resolution requires the ADC to distinguish smaller differences in the input signal, while higher sampling rates require it to complete more conversions per second. Achieving high resolution at high speed therefore places significant demands on the ADC's architecture, analog circuitry, clocking and power budget. If the ADC's input signal is very small, noise can obscure the information you are trying to measure. This becomes particularly challenging at high resolution.

Clock jitter and linearity: Successive Approximation Register (SAR) ADCs depend heavily on their sampling clock. If the sampling instant moves around slightly because of clock jitter, the ADC samples the wrong instantaneous value of the signal. This becomes particularly serious for high-frequency input signals. Ideally, each incremental change in input voltage produces a corresponding change in digital output. In a real ADC, however, nonlinearities can cause the transfer characteristic to deviate from this ideal behavior, introducing distortion and measurement error.

ADC design and solutions

Designing high-performance ADCs from scratch in advanced process nodes requires significant expertise and design time. At Â鶹¹ú²ú, we eliminate these pain points by offering fully customizable, silicon-proven IP. Our 12-bit SAR ADCs support a wide range of sample rates, delivering high precision, excellent linearity and low power. These ADCs can be tailored to your exact system requirements.

Visit our Data Conversion IP, 10-bit ADC and 12-bit ADC web pages to learn more.