ISL55210-ABEVAL1Z

This relatively simple board is intended to provide a quick means to test the performance of the active balun configuration using the ISL55210 wideband, fully differential amplifier (FDA). While all wideband, voltage feedback (VFA), fully differential amplifiers can perform a single-ended input to differential output operation, the frequency span for acceptable input match (or low return loss) is greatly enhanced by the >1.5GHz common mode loop bandwidth internal to the ISL55210.

This design enables quick performance evaluation of an AC‑coupled single‑ended input with a wideband active impedance match, converting to differential in the ISL55210 to provide very broadband balun operation, delivering extremely low input‑referred noise for a matched input using a lower resistor setting in the active match, while achieving exceptional linearity for a 115mW device, with OIP3 greater than 40dBm through 200MHz into a doubly terminated 50Ω load.

This board offers considerable flexibility in input matching and gain through simple changes to four resistor values, and it supports multiple output interface options for either single‑ended or differential operation. In the default configuration, it provides a 50Ω input impedance with better than 34 dB return loss from 1MHz to 400MHz, a single‑ended input to single‑ended measurement output with 10.2dB gain and a −1dB bandwidth from 3MHz to 800MHz, and an input noise figure below 7.5dB when referenced to a 50Ω source.