Abstract: Disclosed herein is a wireless module that includes an oscillation circuit component and an RFIC mounted on a multilayer substrate. The oscillation circuit component includes a clock terminal and a first ground terminal. The RFIC has a second ground terminal that supplies a ground potential to a clock circuit therein and a third ground terminal that supplies a ground potential to an RF circuit therein. The multilayer substrate includes a first conductor layer positioned closest to the plurality of pad electrodes of the RFIC and including a first ground pattern connected to the first and second ground terminals and a second ground pattern connected to the third ground terminal. The first and second ground patterns form a gap between the second and third ground terminals in a plan view as viewed in a stacking direction of the multilayer substrate.

Abstract: Disclosed herein is a circuit board in which a conductor pattern having an annular structure is exposed to the surface thereof. The conductor pattern includes first and second land pattern parts and a first connection part connecting the first and second land pattern parts. The first connection part includes a first section connected to the first land pattern part, a second section connected to the second land pattern part, and a third section connecting the first and second sections. At least a part of the third section of the first connection part is larger in width than the first and section sections.

Abstract: An object of the present invention is to reduce unwanted voice echoed back to the transmitting party in an IP telephone. In order to achieve this object, in the curl cord of the present invention, two microphone lines connected to a differential input type microphone are respectively wired at approximately the same distance from a single speaker line connected to a single end output type speaker. Thereby, noise signals caused by cross-talk to the microphone lines from the speaker line transmitting the voice signal of the transmitting party will be of the same phase and same amplitude. By cancelling out these noise signals by means of common mode rejection in the differential amplifier provided in the base unit, it is possible to reduce the echoing back of unwanted voice to the transmitting party.