A two-phase phase-shift-keyed modulator is realized utilizing a SAW delay line and diode switching circuits. Fundamental performances of the device were clarified experimentally and theoretically.

Fine adjustment of wide-bandwidth SAW filter responses by trimming the interdigital transducer finger lengths was successfully achieved. In SAW devices, second-order effects, such as end effects, diffraction and bulk mode generation, disturb the simple design performances. The slight difference in wide-bandwidth frequency responses between the theoretical and experimental responses was modified by trimming the IDT finger lengths by hand.

Josephson junctions with semiconductor Te barriers have been studied. First, the junctions were fabricated with the process including oxidation of the evaporated Te film surface. The process was generally employed to avoid shorts through pinholes in Te film. Intensive studies on the influence of the Te barrier thickness and oxidation conditions on the junction characteristic parameters were made. The Te layer acts not only as the barrier for tunneling, that is the normal tunneling resistance shows exponential dependence on the Te layer thickness, but also induces proximity effect at the metal interface. The effect was found to play an important role in the junction performance. It was also found that, in the oxidation process, Te itself is oxidized and the junction performance is largely influenced by the Te oxide layer existance. In the second step, junctions free from oxide layer, which showed Josephson effect up to the Te barrier thickness of 40 nm, have been fabricated. By employing smooth surfaced Nb bottom electrode as well as the photolithographic technique comprising the trimming process, uniform junctions perfectly free from pinhole shorts have been realized.

Frequency characteristics of SAW tapped delay lines (TDL's) with equal tap spacing and in-line array are investigated. It is found that reflected SAW echo signals in SAW TLD's cause pulse-like ripples and sharp stopband distortions periodically in the frequency passbands. Tapping design techniques are proposed to remove spurious interference distortion influences on SAW TDL frequency responses. Their applicability is confirmed experimentally. Typical features of a SAW TDL with 101 taps at a 20 MHz bit rate employing 128 rotated Y-cut and X-propagation LiNbO3 substrate are as follows: center frequency is 55.4 MHz, frequency bandwidth is 10 MHz, insertion losses are 3239 dB, and ripples in the passband are about 4 dB.

A transversal equalizer composed of a surface-acoustic-wave tapped delay line and PIN diode control circuits is described. In the amplitude frequency response, the change, which can be expressed in terms of a cosinusoid, can be obtained by controlling the amplitude of the echo signals.