Modulators – Phase shift keying modulator or quadrature amplitude modulator
Patent
1994-09-14
1995-08-29
Grimm, Seigfried H.
Modulators
Phase shift keying modulator or quadrature amplitude modulator
332105, 332119, 375216, 375283, H04L 2712, H04L 2720
Patent
active
054464226
ABSTRACT:
A dual-mode radiotelephone terminal includes a .pi./4-shift DQPSK modulator (11). A dual-mode modulation is achieved by mixing an output of a transmitter oscillator (16) with an output of an offset oscillator (18) to form an injection signal (LO) at a final transmitter frequency, the injection signal being further modulated with a quadrature modulator in a digital mode of operation. In an analog mode of operation the transmitter oscillator or the offset oscillator is frequency modulated and the quadrature modulator is disabled with a bias signal, thereby passing the frequency modulated injection signal without substantial attenuation. The LO signal is regenerated and also phase shifted with a circuit (35) having a frequency multiplier (30) and a frequency divider (34). The circuit outputs two local oscillator (LO) signals (LOA and LOB), each of which directly drives an associated quadrature mixer (36, 38) of the modulator. A control signal is employed for selectively enabling and disabling various of these components as a function of the operating mode, thereby conserving power.
REFERENCES:
patent: 5020076 (1991-05-01), Cahill et al.
patent: 5124672 (1992-06-01), Kuisma
patent: 5228074 (1993-07-01), Mizikovsky
Product Brochure, "ICs For Communications, GSM Transmitter Circuit PBM 2200", Siemens, Ed. 5.90 (1990).
Hulkko Jaakko
Matero Jorma
Mattila Heikki
Grimm Seigfried H.
Mokia Mobile Phones Ltd.
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