Abstract: A bias circuit includes a bias current circuit and a temperature compensation circuit. The bias current circuit includes a first resistor and a first transistor, in a first current path connected between a current terminal of a reference current and a ground, and connected to each other in series, and a second transistor in a second current path connected between the current terminal and the ground, and having a base connected to a collector of the first transistor. The temperature compensation circuit includes a second resistor in the second current path, and connected between an emitter of the second transistor and a base of the first transistor and having a first thermal coefficient, and a third resistor included in the second current path, and connected between the base of the first transistor and the ground and having a second thermal coefficient, different from the first thermal coefficient.

Abstract: A bias circuit includes a bias current circuit and a temperature compensation circuit. The bias current circuit includes a first resistor and a first transistor, in a first current path connected between a current terminal of a reference current and a ground, and connected to each other in series, and a second transistor in a second current path connected between the current terminal and the ground, and having a base connected to a collector of the first transistor. The temperature compensation circuit includes a second resistor in the second current path, and connected between an emitter of the second transistor and a base of the first transistor and having a first thermal coefficient, and a third resistor included in the second current path, and connected between the base of the first transistor and the ground and having a second thermal coefficient, different from the first thermal coefficient.

Abstract: A band selection switch circuit for an amplifier with an impedance matching circuit includes a band selection switch and an impedance compensation circuit. The band selection switch includes a signal port switch configured to selectively connect to one of a common transmit port, transmit and receive (TxRx) ports, and receive ports, and an impedance port switch configured to selectively connect the common transmit port and one of the receive ports and an impedance port. The impedance compensation circuit includes an impedance element connected to the impedance port.

Abstract: A multiband radio frequency transmitter of a transceiver in which a receiving band is varied, includes a transmitting circuit, a receiving band-rejection filter, a power amplifying circuit, and an impedance compensating circuit. The transmitting circuit is configured to generate a transmission signal. The receiving band-rejection filter is configured to vary a rejection band in response to a variation of the receiving band, and reject the receiving band from the transmission signal provided from the transmitting circuit. The power amplifying circuit is configured to amplify the transmission signal that passes through the receiving band-rejection filter. The impedance compensating circuit is configured to compensate for impedance mismatch due to the variation of the rejection band of the receiving band-rejection filter.

Abstract: A multiband radio frequency transmitter of a transceiver in which a receiving band is varied, includes a transmitting circuit, a receiving band-rejection filter, a power amplifying circuit, and an impedance compensating circuit. The transmitting circuit is configured to generate a transmission signal. The receiving band-rejection filter is configured to vary a rejection band in response to a variation of the receiving band, and reject the receiving band from the transmission signal provided from the transmitting circuit. The power amplifying circuit is configured to amplify the transmission signal that passes through the receiving band-rejection filter. The impedance compensating circuit is configured to compensate for impedance mismatch due to the variation of the rejection band of the receiving band-rejection filter.