Theory of Quantization-Interleaving ADC and Its Application in High-Resolution Oscilloscope

The pursuit of high sampling rates and high bandwidth is a long-term theme for oscilloscopes. Recently, accurate test requirements and advanced technology have driven high-resolution oscilloscopes to be a new appeal in both research and industry. Previous high resolution acquisition methods either obtain more bits by reducing the sampling rate or work with many restrictions. In this paper, we propose a novel architecture where parallel ADC is used in quantization interleaving ADC (QIADC) manner, to achieve more bits of resolution. Both the on-chip implementation and the off-chip implementation are presented in a straightforward manner. Although the proposed schemes are different, they have exactly the same effect on resolution enhancement. Based on the basic theory of quantization-sampling model, the principle of QIADC is explained in statistical domain. Furthermore, we derive an explicit expression of enhanced bit. To achieve the goal of both high sampling rate and resolution, a dual channel QIADC oscilloscope prototype is designed and the effectiveness of the proposed method is demonstrated. Experimental results show that i) Smaller signals can be identified and the dynamic range of the system is significantly improved by 5.7dB; ii) The effective number of bits (ENOB) has an improvement of 0.5-bit at multiple frequency points in the 1 GHz band; iii) A higher precision waveform capture is provided through arbitrary waveform test. Finally, the utilization and power overhead of proposed QIADC is also analyzed in this paper.