The analysis and design of a full 360 degrees hybrid coupler phase shifter with integrated distributed elements low pass filters is presented. Pi-section filter is incorporated into hybrid coupler phase shifter for harmonic suppression. The physical size of the proposed structure is close to that of the conventional hybrid coupler phase shifter. The maximum phase shift range is bounded by the port impedance ratio of the hybrid coupler phase shifter. Furthermore, the phase shift range is reduced if series inductance in the reflective load deviates from the optimum value. Numerical and parametric analyses are used to find the equivalent circuit of the pi-section filter for consistent relative phase shift. To validate our analysis, the proposed phase shifter operates at 8.6GHz was fabricated and measured. Over the frequency range of interest, the fabricated phase shifter suppresses second harmonic and achieves analog phase shift of 0 to 360 degrees at the passband, agreeing with the theoretical and simulation results.

Accurate estimation of accentual attribute values of words, which is required to apply rules of Japanese word accent sandhi to prosody generation, is an important factor to realize high-quality text-to-speech (TTS) conversion. The rules were already formulated by Sagisaka et al. and are widely used in Japanese TTS conversion systems. Application of these rules, however, requires values of a few accentual attributes of each constituent word of input text. The attribute values cannot be found in any public database or any accent dictionaries of Japanese. Further, these values are difficult even for native speakers of Japanese to estimate only with their introspective consideration of properties of their mother tongue. In this paper, an algorithm was proposed, where these values were automatically estimated from a large amount of data of accent types of accentual phrases, which were collected through a long series of listening experiments. In the proposed algorithm, inter-speaker differences of knowledge of accent sandhi were well considered. To improve the coverage of the estimated values over the obtained data, the rules were tentatively modified. Evaluation experiments using two-mora accentual phrases showed the high validity of the estimated values and the modified rules and also some defects caused by varieties of linguistic expressions of Japanese.