Patent ID: 7274317

Claim:
A direct conversion transmitter comprising: a digital-to-analog converter which converts an input digital signal into an analog signal; a baseband analog filter which filters a specific band of the analog signal output from the digital-to-analog converter; a phase conversion element which receives a local oscillation signal and outputs an in-phase local oscillation signal and a quadrature phase local oscillator signal; first and second mixers which mix signals output from the baseband analog filter with the in-phase local oscillation signal and the quadrature phase local oscillation signal output from the phase conversion element, and output an in-phase high-frequency vector signal and a quadrature phase high-frequency vector signal; and a drive amplifier which amplifies high frequency signals output from the first and second mixers; wherein at least one of the digital-to-analog converter, the baseband analog filter, the first and second mixers, and the drive amplifier comprises a switching element comprising vertical bipolar junction transistors (BJTs).