Distributed Amplifiers: Practical Considerations and Experimental Results

The principle of distributed amplification has recently been proposed as a means for obtaining amplification with conventional vacuum tubes over very great bandwidths. Unlike conventional circuits, distributed amplifiers have an attainable gain-bandwidth product which is not limited by shunt capacitance associated with the vacuum tubes and circuit wiring. This paper cites experimental results which essentially corroborate the predictions based on first-order theory. It is pointed out that when extreme bandwidths are sought, these predicted characteristics are modified by several factors which are difficult to control in actual practice. Corrective methods are available, however, which permit a limited control over these modifying effects. These methods are discussed and their applications are illustrated by measurements on actual amplifiers with pass-bands on the order of 200 to 300 Mc.