Semiconductor integrated circuit for communication, radio-communications apparatus, and transmission starting method
First Claim
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1. A semiconductor integrated circuit for communication comprising:
- a modulation circuit for performing phase modulation and amplitude modulation;
a phase detection circuit for detecting a phase component of a signal modulated by said modulation circuit;
an amplitude detection circuit for detecting an amplitude component of the signal modulated by said modulation circuit;
a power amplifier for amplifying the power of a transmission signal and outputting the amplified transmission signal;
a feedback path for feeding a signal corresponding to an output level of said power amplification circuit back to said amplitude detection circuit;
a variable gain amplification circuit provided on a forward path between said amplitude detection circuit and said power amplification circuit for generating a control voltage for an amplitude control;
a loop filter for setting a frequency bandwidth of an amplitude control loop, said amplitude control loop including said feedback path and said forward path; and
a sequence control circuit for sequentially generating control signals and supplying the generated control signals to associated circuits for operating said circuits in a predetermined order based on a command supplied thereto.
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Abstract
In a polar loop based radio-communications apparatus having a phase control loop for controlling the phase of a carrier outputted from an oscillator for transmission, and an amplitude control loop for controlling the amplitude of a transmission output signal outputted from a power amplification circuit, the phase control loop is first started while maintaining the amplitude control loop in an off state at the outset of transmission, and the amplitude control loop is started after stabilizing the phase control loop.
22 Citations
11 Claims
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1. A semiconductor integrated circuit for communication comprising:
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a modulation circuit for performing phase modulation and amplitude modulation; a phase detection circuit for detecting a phase component of a signal modulated by said modulation circuit; an amplitude detection circuit for detecting an amplitude component of the signal modulated by said modulation circuit; a power amplifier for amplifying the power of a transmission signal and outputting the amplified transmission signal; a feedback path for feeding a signal corresponding to an output level of said power amplification circuit back to said amplitude detection circuit; a variable gain amplification circuit provided on a forward path between said amplitude detection circuit and said power amplification circuit for generating a control voltage for an amplitude control; a loop filter for setting a frequency bandwidth of an amplitude control loop, said amplitude control loop including said feedback path and said forward path; and a sequence control circuit for sequentially generating control signals and supplying the generated control signals to associated circuits for operating said circuits in a predetermined order based on a command supplied thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A transmitter for transmitting a data signal, the transmitter comprising oscillator means for producing an output signal whose phase and/or frequency is dictated by a control signal, and phase comparison means for producing said control signal by comparing said output signal with the data signal,
wherein the phase comparison means comprises analogue phase detection means and digital phase frequency detection means, each of which is capable of producing said control signal by measuring the phase and/or frequency difference between said output signal and the data signal, wherein said transmitter is arranged to be capable of operating in a GSM-GSMK mode (Global System for Mobile Communication-Gaussian Minimum Shift Keying) or a GSM-EDGE mode (Global System for Mobile Communication-Enhanced Data Rates for GSM Evolution) in one or more bands, and wherein said transmitter further comprises amplification means for amplifying the power of said output signal and wherein the analogue phase detection means is arranged, when performing said measurement in said GSM-GSMK mode, to use said output signal before said amplification and, when performing said measurement in said GSM-EDGE mode, to use said output signal after said amplification.
Specification