A 4 Gsample/s 2 bits flash ADC with 2-4 GHz input bandwidth for radio astronomy applications
This paper presents the design and the measurement results of a high speed A/D converter (ADC or digitizer) developed for radio-astronomy applications and especially for the ALMA (Atacama Large Millimeter Array) project. This monolithic digitizer is implemented in a BiCMOS 0.35 mu m SiGe process for high frequency mixed-signal applications. The main characteristics of this circuit are a 2 bits resolution with 3 quantization levels (equivalent to 1.5 bits) with 4 Gsample/s rate, a wide input bandwidth from 2 GHz up to 4 GHz under full Nyquist condition. The adopted digitizer architecture is that of a conventional flash analog to digital converter structure. The overall chip dissipates 652 mW under +/- 1.25 V supply and the die area is 5.4 mm(2).
radio astronomy a/d converter sige high-speed sampler giga-samples