High Speed Differential Amplifier in a Active Balun Configuration Evaluation Board


This relatively simple board is intended to provide a quick means to test the performance of the active balun configuration using the ISL55210. While all wideband, voltage feedback (VFA), fully differential amplifiers (FDA) 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.

Quickly evaluate performance for a breakthrough new amplifier type.

  • AC coupled single ended input with a wideband “active” impedance match
  • Convert to differential in the ISL55210 to give a very broadband “balun” operation
  • Extremely low input referred noise for a matched input using the much lower resistor setting of the active match
  • Exceptional OIP3 for 115mW device. At a doubly terminated 50Ω load, OIP3> 40dBm through 200Mhz

This board offers considerable flexibility in the input match and gain by simply changing 4 resistor values. It also offers several possible output interfaces to either get single ended or run differential output. As delivered, the default configuration delivers a -

  • 50ohm input impedance with >34dB return loss from 1Mhz to 400Mhz
  • Single ended input to single ended measurement output with 10.2dB gain and -1dB span from 3Mhz to 800Mhz
  • Input noise figure <7.5dB referenced to a 50Ω source.

Key Features

  • Easily settable gain and input impedance (change only 4 resistors)
  • Wideband output balun for easy single ended response measurements
  • Excellent simulation model available in iSim PE
  • Optional differential output port for FDA only response


  • IF receiver chains needing the smallest size single to differential solution
  • Ultrasound catheter systems needing flexible, wideband input match
  • MRI systems requiring single to differential with no magnetic elements
  • Lower frequency HF receivers needing the lowest power with exceptional dynamic range

Related Evaluation Platforms

ISL55210-ABEVAL1Z Active Balun Configured High Speed Differential Amp Eval Board

ISL55210-ABEVAL1Z Active Balun Configured High Speed Differential Amp Eval Board

Related Products




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