Terminology » SAR (Successive Approximation Register) ADC : Key Advantages and disadvantages

SAR (Successive Approximation Register) ADC : Key Advantages and disadvantages

sar adc successive approximation register adc analog to digital converter adc

Introduction : A SAR ADC converts analog input to digital output by successively approximating the input voltage, starting with the most significant bit and refining the estimate until the least significant bit is resolved. It is widely used due to its balance of speed, accuracy and low power consumption.

SAR (Successive Approximation Register) ADC

SAR type ADC

Figure : SAR Type ADC

Figure depicts a block diagram of a SAR type ADC. SAR stands for Successive Approximation Register.

SAR type ADCs are commonly used in digital circuits to interface with microprocessors. The conversion time in a SAR ADC is uniform for any analog voltage and is equal to n * T_CLK.

Advantages of SAR ADC

Following are some of the benefits of SAR ADC.

  1. It offers excellent power efficiency.
  2. It offers good linearity performance.
  3. It’s design has moderate complexity.
  4. It offers wide range of resolutions.

Disadvantages of SAR ADC

Following are some of the drawbacks of Successive Approximation Register ADC type.

  1. Conversion time increases with resolution. High resolution SAR ADCs can be slower.
  2. Sensitive to comparator noise.
  3. Input bandwidth is limited by S&H circuit.
  4. DAC settling time affects speed.
  5. Speed is limited to approximately 5 MBPS.

Conclusion : SAR ADCs are versatile, efficient and suitable for wide range of applications, from portable devices to industrial control systems, though they are generally slower than flash ADCs for very high speed needs.