Communication semiconductor integrated circuit, a wireless communication apparatus, and a loop gain calibration method
First Claim
1. A method of calibrating gain variation for use in a transmitter comprising a phase control loop for controlling a phase of a carrier signal from a transmitting oscillator and an amplitude control loop for controlling amplitude of an output from a power amplifier, a variable gain amplifier on a forward path from an amplitude detection circuit to said power amplifier, and selectable means to switch a loop order of said amplitude control loop, said method comprising the steps of:
- assessing gain variation of said amplitude control loop by setting by said selectable means a loop order less than a loop order for normal operation; and
calculating said gain variation according to a result of said assessment.
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Accused Products
Abstract
A polar-loop wireless communication apparatus includes, on a forward path between an amplitude detector and a power amplifier which constitute an amplitude control loop, a variable gain amplifier and a switch to change characteristics of a loop filter to output a frequency bandwidth of the amplitude control loop to an order less than an order for normal operation. The system is operated with the characteristics set to the lower order to measure outputs from the power amplifier to calibrate the output power of the power transmitter, and the register is operated with the characteristics set to the higher order to measure the open loop gain of the amplitude control. According to results of the calculation, data to correct gain characteristics of the variable gain amplifier with respect to an output control signal is stored in a nonvolatile memory of a baseband circuit.
62 Citations
8 Claims
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1. A method of calibrating gain variation for use in a transmitter comprising a phase control loop for controlling a phase of a carrier signal from a transmitting oscillator and an amplitude control loop for controlling amplitude of an output from a power amplifier, a variable gain amplifier on a forward path from an amplitude detection circuit to said power amplifier, and selectable means to switch a loop order of said amplitude control loop, said method comprising the steps of:
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assessing gain variation of said amplitude control loop by setting by said selectable means a loop order less than a loop order for normal operation; and calculating said gain variation according to a result of said assessment.
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2. A method of calibrating an amplitude modulation loop for use in a transmitter, said amplitude modulation loop having a type I mode and a type II mode and comprising a forward path and a feedback path, each connecting modulation generating means with amplification means operating on a carrier signal, each path containing a loop amplifier and said loop amplifiers being arranged to respond to a common gain control signal in opposite senses,
wherein said method comprises: -
steps of setting said amplitude modulation loop to the type I mode; recording the output of said amplification means in response to variation of said common gain control signal; and compensating said recorded response to enable it to be used as calibration information for an operation of said type II mode of said amplitude modulation loop. - View Dependent Claims (3, 4, 5)
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6. A method of calibrating an amplitude modulation loop for use in a transmitter, said amplitude modulation loop comprising a forward path and a feedback path each coupling with modulation means and amplification means operating on a modulated carrier signal, each path containing a loop amplifier, said loop amplifiers being arranged to respond to a common gain control signal in opposite senses and one of said loop amplifiers having a corrective gain offset,
wherein said method comprises: -
introducing a predetermined test modulation signal into said forward path; and assessing the corrective effect of said corrective gain offset on loop operation by comparing sideband amplitude of the output of said amplification means at different frequencies of said predetermined test modulation signal. - View Dependent Claims (7, 8)
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Specification