Linville power plane stability and bandwidth improvements in a minimum-drift video amplifier

The stability of a previously designed, minimum-drift video amplifier is studied over a wide bandwidth. An original upper frequency of 2 MHz has been extended to 20 MHz using high-frequency compensation techniques. The Y-parameters were measured at 3.0 MHz and used in the Linville power plane to determine the input and output power curves. Two techniques for enhancing the system response have been investigated. In the mismatch method, a stem stability factor was chosen to keep the system stability over a wide band of frequencies. The neutralization method in which the intrinsic feedback parameter Y₁₂ is neutralized is discussed. While both methods show acceptable stability improvements, the mismatch method is used because it does not require an additional transformer to the system. The video amplifier LM733 driven by the N-channel BFR84 MOSFET has been used for demonstration