Selecting the Optimal Resolution and Conversion Frequency for A/D and D/A Converters

When a signal is converted by means of a converter circuit as an analog to digital converter (ADC) or a digital to analog converter (DAC) the quantization and sampling effects appeared, which causes a quality decrease of the signal that is usually indicated by the signal to noise ratio (SNR). This SNR lost decreases when the resolution and conversion frequency of the converter is increased. Nevertheless, in this way the cost and the complexity of the circuit are also unnecessarily increased. In this work, a method to select the optimal resolution and the conversion frequency is proposed. This method, which is based on the dynamic characteristic of the converter and the signal, utilizes the desirable resulting signal quality as the constraint. From the signal´s SNR and the quantity of it that can be lost the minimum number of bits N is obtained. Then, from N the minimum conversion frequency is calculated. A mathematical analysis and a simulation test of the method are carried out. Results can be directly applied to select the main dynamics characteristics of the ADC, the DAC or, in general, of a DAS.