A device comprising: a first quadrature modulator configured to receive an in-phase portion of a baseband signal and a quadrature portion of the baseband signal, and to produce a first portion of an output signal according to the in-phase and quadrature portions of the baseband signal; a second quadrature modulator configured to receive a first modified signal and a second modified signal, and to produce a second portion of the output signal according to the first and second modified signals; an output circuit configured to sum the first and second portions of the output signal, and to transmit the output signal to an antenna; and a mode selection circuit configured to turn on the first quadrature modulator, to receive a control signal, and to determine whether to turn on the second quadrature modulator according to the control signal; wherein the mode selection circuit is configured to be coupled to a controller, the controller configured to receive parameters of a transmission, and to produce the control signal according to the parameters of the transmission, wherein the parameters of the transmission comprise a current resource block configuration of the transmission, a current transmission power of the transmission, and an operating band of the transmission, wherein the mode selection circuit is further configured to: refrain from turning on the second quadrature modulator in response to the current resource block configuration being in the center of a channel for the transmission, wherein the mode selection circuit is further configured to: turn on the second quadrature modulator in response to the current resource block configuration being at the edge of a channel for the transmission, and wherein the mode selection circuit is further configured to: determine a threshold transmission power according to the operating band of the transmission; and refrain from turning on the second quadrature modulator in response to the current transmission power of the transmission being less than or equal to the threshold transmission power. a first quadrature modulator configured to receive an in-phase portion of a baseband signal and a quadrature portion of the baseband signal, and to produce a first portion of an output signal according to the in-phase and quadrature portions of the baseband signal; a second quadrature modulator configured to receive a first modified signal and a second modified signal, and to produce a second portion of the output signal according to the first and second modified signals; an output circuit configured to sum the first and second portions of the output signal, and to transmit the output signal to an antenna; and a mode selection circuit configured to turn on the first quadrature modulator, to receive a control signal, and to determine whether to turn on the second quadrature modulator according to the control signal; wherein the mode selection circuit is configured to be coupled to a controller, the controller configured to receive parameters of a transmission, and to produce the control signal according to the parameters of the transmission, wherein the parameters of the transmission comprise a current resource block configuration of the transmission, a current transmission power of the transmission, and an operating band of the transmission, wherein the mode selection circuit is further configured to: refrain from turning on the second quadrature modulator in response to the current resource block configuration being in the center of a channel for the transmission, wherein the mode selection circuit is further configured to: turn on the second quadrature modulator in response to the current resource block configuration being at the edge of a channel for the transmission, and wherein the mode selection circuit is further configured to: determine a threshold transmission power according to the operating band of the transmission; and refrain from turning on the second quadrature modulator in response to the current transmission power of the transmission being less than or equal to the threshold transmission power. wherein the mode selection circuit is configured to be coupled to a controller, the controller configured to receive parameters of a transmission, and to produce the control signal according to the parameters of the transmission, wherein the parameters of the transmission comprise a current resource block configuration of the transmission, a current transmission power of the transmission, and an operating band of the transmission, wherein the mode selection circuit is further configured to: refrain from turning on the second quadrature modulator in response to the current resource block configuration being in the center of a channel for the transmission, wherein the mode selection circuit is further configured to: turn on the second quadrature modulator in response to the current resource block configuration being at the edge of a channel for the transmission, and wherein the mode selection circuit is further configured to: determine a threshold transmission power according to the operating band of the transmission; and refrain from turning on the second quadrature modulator in response to the current transmission power of the transmission being less than or equal to the threshold transmission power. determine a threshold transmission power according to the operating band of the transmission; and refrain from turning on the second quadrature modulator in response to the current transmission power of the transmission being less than or equal to the threshold transmission power.