Nec Corporation

Nippon Telegraph and Telephone Corporation

Hiroyuki Misawa

Noboru Saegusa

Akio Yotsutani

Shinji Kumataka

Kosuke Hashimoto

Kouzo Kobayashi

In a cordless key telephone system, access units are located in groups corresponding to service areas for broadcasting radio signals on a control channel or on an assigned speech channel to cordless stations. A main controller selects one of the access units for each service area in response to an incoming call from the switched telephone network and sends a first alert signal to the selected access units to cause them to broadcast a recurrent sequence of second alert signals containing the identifiers of standby cordless stations. The second alert signal is received by each standby cordless station and an ACK signal is transmitted if the received signal contains its identifier. The ACK signal is copied by each access unit for transmission to the main controller, whereupon it returns a proceed-to-assign signal if the number of the received copies of the ACK signals is equal to the number of all standby stations. The proceed-to-assign signal is received by the selected access units and a channel assignment signal is broadcast indicating the assigned channel. On receiving it, each station is switched to the assigned channel and one of the stations in each area transmits an end-of-switching signal to cause the access units to broadcast ringing signals containing the identifiers of the alerted stations. In response to a given cordless station going off hook, an off-hook signal is sent from it and copied by the associated access unit for transmission to the main controller, which returns a turn-on signal to allow the given station to activate its speech circuit.

Cordless key telephone system capable of quickly answering incoming calls

A power supply wiring arrangement of a semiconductor integrated circuit formed on a semiconductor chip, including a plurality of pairs of metal bumps formed on the semiconductor chip, a plurality of conductor strips each extending between the bumps forming each of the pairs of metal bumps, and a plurality of thick-layer wiring strips directly connected to selected ones of the metal bumps and the conductor strips, the thick-layer wiring strips being substantially identical in material and in thickness to the metal bumps.

Semiconductor integrated circuit

A gate array integrated circuit includes four internal logic circuits each composed of a current mode logic circuit and an emitter follower circuit having an input connected to an output of the current mode logic circuit. One wired logic circuit is formed by interconnecting output terminals of four emitter follower circuits. An one end of an interconnection wiring conductor for interconnecting the output terminals of the four emitter follower circuits is connected to an output terminal of a first emitter follower circuit, and the other end of the interconnection wiring conductor is connected to an output terminal of fourth emitter follower circuit of the N emitter follower circuits. The interconnection wiring conductor serially extends and traces all the output terminals of the four emitter follower circuits from the output terminal of the first emitter follower circuit to the output terminal of the fourth emitter follower circuit without branch, so that the output terminals of the second and third emitter follower circuits are connected to an intermediate portion of the interconnection wiring conductor in the order. A pair of resistors or constant current sources having the same value are connected to only the output terminals of the first and fourth emitter follower circuits, respectively.

Growing community of inventors

Tokyo, Japan

Hiroyuki Misawa