Active Analog Splitter

Active Analog Splitter: Leveraging an Active Analog Splitter to Increase an ADC System’s Sampling Rate

A common know method to increase the sampling rate of an ADC is to position two or more of them in parallel and sample their inputs at different phases of the system’s sampling signal (usually a standard clock signal). For example, to double the sampling rate, place two of the ADCs in question in parallel, and sample one with direct clock and sample the other with indirect clock (i.e. 180° phase shifter clock). The sampling rate can be increased by another factor of two by adding two more ADCs in parallel to the system and using 90° and 270° clocks for sampling.

While this approach increases the needed number of ADCs in the system, it also requires precise phase matched delivery of both input data and sampling clock signals to the parallel devices. Phase matched clock splitters can be used for the accurate distribution of the sampling clock signal. To eliminate as much aperture jitter as possible caused by the misalignment of the input data signals into the multiple ADCs, an accurate analog splitter is necessary.

Passive solutions exist, but they are large and unfortunately attenuate the input signal during the “splitting process”. An active approach is much better in that it is compact, provides stable low signal gain/loss (can be adjustable), and generates several highly phase matched copies of the input at its outputs.

ADSANTEC’s ASNT6112-KMC is a broadband 1-4 active linear signal splitter having an input analog bandwidth of 25GHz. It accepts an analog signal and produces 4 exact phase matched copies of it with minimal delay. The five 50Ω fully differential I/Os can also be used in a single-ended manner if desired using AC or DC coupling as appropriate. The part remains highly linear for input analog signals up to 1000mVpk-pk differential.

A custom high performance metal-ceramic packaging solution is used to house the IC. The package is compact and easily soldered to commonly used printed circuit boards (PCBs).

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