Broadband power amplifiers and 4-quadrant amplifiers are used in many applications. Especially DC coupled 4-quadrant amplifiers are generic units, because users have a bipolar current or voltage source and an electronic load in sink mode. The power starts from a few Watt to Kilowatt and the bandwidth begins with DC to about 5MHz. SMT sells amplifiers from Toellner and FuG.
Power Amplifiers from Toellner
4 - Quadrant Power Amplifier from FuG
