Waveform generator for use in iq modulation
AssigneeFreescale Semiconductor, Inc.
InventorNadim Khlat
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Abstract
A waveform generator for use in IQ modulation in a wireless cellular device having an FM waveform generator (104) that is programmable to generate a desired FM frequency deviation; a digital accumulator (108, 110, 112) to provide phase generation. First and second look-up tables 114 and 116 use the 6 MSBs and the 6 LSBs of 12-bit digital accumulator values to look up phase-space values that are combined in complex multipliers (130, 140), which are re-used from other parts of the circuit. This provides the following advantage(s): Support of both FM and I/Q modulation techniques for constant envelope modulation; low cost implementation; and flexibility to address multimode systems.
Claims14
A waveform generator (100) for use in IQ modulation, comprising:
- digital frequency modulation waveform generator means (104) for generating digital values representative of any of a predetermined range of desired frequency modulation schemes;
- and
- digital accumulator means (108, 110, 112) for accumulating digital values produced by said digital frequency modulation waveform generator means.
An integrated circuit transceiver arrangement for use in a wireless communication device and comprising a waveform generator according to any preceding claim.
A transceiver for use in a wireless communication device comprising:
- waveform generator means (100) for producing in-phase and quadrature-phase signals (I, Q) for digital frequency modulation;
- a first phase-locked-loop (150) having a receive voltage-controlled oscillator (152);
- a second transmit loop (160) having a transmit voltage-controlled oscillator (162) and receiving a signal from said receive voltage-controlled oscillator;
- and
- IQ modulator means (170) for receiving said in-phase and quadrature-phase signals from said waveform generator means and for producing an IQ modulated signal for transmission.
Dependencies are inferred from the claim text.