Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Patent
1996-07-08
1998-07-28
Pham, Chi H.
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
455 93, 455110, 375216, H04B 104
Patent
active
057873623
ABSTRACT:
A circuit is provided for use in a dual mode mobile phone for selectively one of phase modulating or frequency modulating an RF signal. The circuit includes an IQ generator for generating one of first quadrature waveshapes or second quadrature waveshapes in response to a modulating signal; a quadrature mixer for mixing the first quadrature waveshapes or the second quadrature waveshapes with an RF signal to generate a phase modulated RF signal or a frequency modulated signal, respectively; and a limiter, such as at least one limiting amplifier, that has an input coupled to an output of the quadrature mixer for reducing an amplitude modulation component of only the frequency modulated signal. The at least one limiting amplifier has an input coupled to a limit control signal that has a magnitude selected for setting a dynamic range of the at least one limiting amplifier. The phase modulated signal may be a .pi./4-DQPSK signal. This invention also teaches an analog mobile phone that employs the IQ modulator and limiter to generate a FM transmission signal, and that furthermore requires but a single variable local oscillator that is used to quadrature mix and up-convert the transmitted FM signal, and that is also used to down-convert a received FM signal to an IF signal. The IF signal has a frequency equal to the channel spacing between the transmitted and received FM signals, or 45 MHz in an analog mobile phone embodiment compatible with IS-91.
REFERENCES:
patent: 4955039 (1990-09-01), Rother et al.
patent: 5008925 (1991-04-01), Pireh
patent: 5020076 (1991-05-01), Cahill et al.
patent: 5020092 (1991-05-01), Phillips et al.
patent: 5079520 (1992-01-01), Rapeli
patent: 5124672 (1992-06-01), Kuisma
patent: 5224119 (1993-06-01), Barabash et al.
patent: 5291474 (1994-03-01), Ikonen et al.
patent: 5301367 (1994-04-01), Heinonen
patent: 5325075 (1994-06-01), Rapeli
patent: 5390168 (1995-02-01), Vimpari
patent: 5422931 (1995-06-01), Austin-Lazarus et al.
patent: 5471652 (1995-11-01), Hulkko
patent: 5590402 (1996-12-01), Samson et al.
patent: 5642378 (1997-06-01), Denheyer et al.
Nokia Mobile Phones Limited
Pham Chi H.
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