One of these boards is included in the Hardware Kit with the GSPS ADC Reference Boards. Since the analog inputs to the ADC1xDxx00RB are differential and most signal sources are single-ended, these balun boards are generally used to achieve single-ended-to-differential conversion. In case both I- and Q-inputs are simultaneously driven with a similar signal, an additional balun board of the same type may be desired.
Incidentally, this balun board may also be used to do differential-to-single-ended conversion. For example, this balun board may be used when observing the DCLK+/- or RCOut+/- signal on a single-ended scope when exploring the AutoSync feature on the GSPS ADC Reference Boards.
The ADC-WB-BB uses the TC1-1-13MA+ from Mini-Circuits, which is designed for wide-band functionality and low cost. Since the input impedance of the GSPS ADCs are 100Ω, the impedance of most signal generators are 50Ω, and the impedance ratio of this balun is 1:1, the extra 100Ω across the output is present for impedance matching. However, this does incur an additional 3dB insertion loss.