A received signal passed through an HPF is supplied to an input switching circuit where the signal is switched to any of HIGH BAND, MID BAND and LOW BAND circuitry. The received signal of each band circuitry is band-switched by an RF amplification input BPF, RF-amplified by an RF amplifier and then a resultant received signal is supplied from an RF amplification output BPF. The received signal is mixed with a local oscillation signal from a local oscillator circuit by a mixer circuit to generate an intermediate-frequency signal. The intermediate-frequency signal is supplied to a first IF amplifier circuit, a SAW filter and a second IF amplifier circuit. A PLL channel select circuit outputs a switching voltage for each band and conduct PLL control for the local oscillator circuit.

A method and circuit for transmitting a data-modulated high-frequency data signal f.sub.C from a transmitter to a receiver, for transmitting data between a read-write device (RWD) and at least one mobile data memory (MDM) in an identification system that has a number of mobile data memories (MDM) which are placed on objects and which are provided for detecting object-specific status data and/or process data. Such an identification system is particularly useful, e.g., in a shipping, transport and/or manufacturing system of the individual objects. In addition to the transmitted high frequency data signal f.sub.C, a further high-frequency data signal f.sub.S is transmitted, which serves to convert the frequency and/or to modulate the carrier code of the high-frequency data signal f.sub.C.

A multiple frequency RF communications receiver is disclosed which permits greater integration on standard silicon chips and consumes less power than previous receivers. A new method for selecting the various frequency bands with a high amount of isolation and low power consumption is described. Compared to previous receiver implementations, there is no loss of selectivity in the receiver.

A cellular phone covering a plurality of frequency bands, includes (a) an antenna, (b) a high-frequency circuit, (c) an antenna-matching circuit electrically connecting in series between the antenna and the high-frequency circuit, and (d) a first unit which varies a ground length in accordance with a frequency band in which the cellular phone makes communication with others, the ground length being defined as a length of a ground area for the antenna-matching circuit.

A multi-mode wireless device having a transceiver including a multi-mode transmitter and a multi-mode receiver. The transmitter can include a multi-mode transmit baseband portion configured to support all of the transmit modes. Similarly, the receiver can include a multi-mode baseband portion that is configured to support all of the receive modes. The transmitter can also include a frequency conversion stage that can convert the output from the transmit baseband portion to the desired transmit frequency. Multiple power amplifiers in parallel, each configured to support one or more of the operating modes, can selectively amplify the transmit signals. The receiver can include multiple low noise amplifiers (LNAs) in parallel, each configured to selectively amplify the received signals of one or more of the operating modes. The output of the LNAs can be coupled to a frequency conversion stage that downconverts the received signals and provides them to the baseband portion.