Patent ID: 8532591
Filing Date: 2013-09-10
Classification: H03F,H03G,H04B

Abstract:
1. A transmission circuit that polar-modulates an input signal by switching an operation mode between a high-output mode in which the transmission circuit operates in a high-output region and a low-output mode in which the transmission circuit operates in a low-output region, the transmission circuit comprising: a signal generation section that generates an amplitude signal and a phase signal on the basis of the input signal; an amplitude signal driving section that generates a first control voltage based on the amplitude signal in the high-output mode, and generates a second control voltage at a predetermined level and a first bias current based on the amplitude signal in the low-output mode; a variable gain adjustment section that adjusts a power level of the phase signal; and a power amplifier: to a power supply terminal of which the first control voltage is supplied and which amplitude-modulates the phase signal having the adjusted power level on the basis of the first control voltage, in the high-output mode; and to the power supply terminal of which the second control voltage is supplied and to an input terminal of which the first bias current is supplied and which amplitude-modulates the phase signal having the adjusted power level on the basis of the first bias current and the second control voltage, in the low-output mode, wherein in a specific region in the low-output region and close to the high-output region,