초록 ▼

A CDMA transmitter having a variable gain circuit inserted between a transmitter mixer and a transmitter antenna. The gain is controlled in response to the RF output power so that the spurious emission level at the maximum RF output power and that at output power reduced by a predetermined amount ca

A CDMA transmitter having a variable gain circuit inserted between a transmitter mixer and a transmitter antenna. The gain is controlled in response to the RF output power so that the spurious emission level at the maximum RF output power and that at output power reduced by a predetermined amount can be both satisfied. This makes it possible to increase the degree of freedom of choosing circuit components in the RF stage.

대표청구항 ▼

[ What is claimed is:] [1.] A CDMA (code division multiple access) transmitter for transmitting a first signal at an RF (radio frequency) frequency under first limitations on a spurious emission level at a first RF output power and second limitations on a spurious emission level at a second RF outpu

[ What is claimed is:] [1.] A CDMA (code division multiple access) transmitter for transmitting a first signal at an RF (radio frequency) frequency under first limitations on a spurious emission level at a first RF output power and second limitations on a spurious emission level at a second RF output power smaller than the first RF output power by a predetermined amount, the first RF output power being a maximum RF output power of said transmitter, the second limitations being severer than the first limitations, said CDMA transmitter comprising:a transmitter mixer for mixing a second signal to be transmitted with a local oscillation signal to produce the first signal at the RF frequency;a transmitter antenna for radiating the first signal at the RF frequency;a power control circuit having a variable first gain responsive to a power control signal for supplying said transmitter antenna with the first signal produced from said transmitter mixer and the first gain, the power control signal corresponding to an RF power level at which the first signal is to be radiated by said transmitter antenna; anda power control amplifier connected to an input side of said transmitter mixer and having a variable second gain responsive to the power control signal for amplifying the second signal with the second gain to provide said transmitter mixer with the amplified second signal;said power control circuit varying the first gain in response to the power control signal so as to maximize the first gain based upon the power control signal.