Telecommunications – Receiver or analog modulated signal frequency converter – With wave collector
Reexamination Certificate
1998-07-22
2001-06-26
Maung, Nay (Department: 2681)
Telecommunications
Receiver or analog modulated signal frequency converter
With wave collector
C455S254000, C455S248100, C455S283000, C455S289000, C330S051000, C330S151000
Reexamination Certificate
active
06253070
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a code division multiple access (“CDMA”) system.
The CDMA system includes a number of spaced transmitters. Each transmitter transmits to each of a plurality of handsets. The handsets can either be close to the base station or distant from the base station. The base station needs to transmit enough power so that all the handsets can receive the signal.
Sometimes, however, when the handset is too close to the transmitter, too much power may be received by the handset. The desired spectrum may be lower in amplitude than the undesired spectrum. Moreover, the desired and undesired spectra may be close enough in frequency such that the undesired spectra might not be removable by filtering. Problems occur from overdriving the input to the LNA, forming undesirable signal distortion and intermodulation products.
SUMMARY
According to the present disclosure, a single diode is used as a shunt RF bypass across an low noise amplifier (“LNA”). The diode turns on to bypass the transistor that forms the amplifier. The transmitter may be turned-off when the diode is turned-on in order to conserve bias current and prevent the transistor from generating spurious signals. Hence, amplification can be terminated when the incoming signal is sufficiently strong. This can avoid intermodulation distortion that could otherwise occur from overamplification.
An important feature of the present system is that the bias circuitry for the diode is included as part of the RF matching networks of the amplifier. This minimizes the number of components which are needed.
REFERENCES:
patent: 5230096 (1993-07-01), Davies et al.
patent: 5574405 (1996-11-01), Razavi
patent: 5589797 (1996-12-01), Gans et al.
patent: 5898911 (1999-04-01), White
patent: 5914634 (1999-06-01), Oberhammer
patent: 5995814 (1999-11-01), Yeh
Davis Temica M.
Denso Corporation
Fish & Richardson P.C.
Maung Nay
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