Nanosecond Pulse Transformers

The transmission-line approach to the design of transformers yields a unit with no first-order rise-time limit since this approach uses distributed rather than lumped constants. The total time delay through the transmission-line-type transformer may exceed the rise time by a large factor, unlike conventional transformers. The extra winding length can be employed to improve the low-frequency response of the unit. Transformers can be made for impedance matching, pulse inverting, and dc isolation within the range of about 30 to 300 ohms with rise times of less than 0.5 × 10-9 seconds, and magnetizing time constants in excess of 5 × 10-7 seconds. Voltage-reflection coefflcients of 0.05 or less, and voltage-transmission efficiencies of 0.95 or better can be achieved.