Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Reexamination Certificate
1999-09-28
2001-07-10
Hunter, Daniel (Department: 2684)
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
C455S313000, C455S341000
Reexamination Certificate
active
06259903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The invention relates to a tuner. The invention further relates to an IF amplifier for use in such a tuner. The invention further relates to a mixer oscillator integrated circuit comprising such an IF amplifier.
2. Description of The Related Art
Such a tuner, IF amplifier, and mixer oscillator integrated circuit are known in the art, and can be used in television receivers, radio receivers, and other applications.
A disadvantage of the known tuner, IF amplifier and mixer oscillator integrated circuit, is that there has to be two kinds of tuners, IF amplifiers and mixer oscillator integrated circuits, namely, depending on the output of the tuner, a symmetrical and an asymmetrical version.
SUMMARY OF THE INVENTION
An object of the invention is to obtain a tuner, an IF amplifier and a mixer oscillator integrated circuit that can be used for both symmetrical and asymmetrical outputs. To this end a first aspect of the invention provides a tuner comprising an input circuit and a mixer oscillator stage, said mixer oscillator stage comprising an IF amplifier coupled to an output of the tuner, characterized in that the tuner further comprises switching means for switching between a symmetrical and an asymmetrical output mode, whereby, in the asymmetrical mode, one output of the tuner is coupled to a reference voltage by the switching means, and the tuner comprises control means for controlling the switching operation.
A second aspect of the invention provides an IF amplifier for use in such a tuner.
A third aspect of the invention provides a mixer oscillator integrated circuit comprising such an IF amplifier.
In this way, it is possible to use the same tuner, IF amplifier or mixer oscillator integrated circuit, respectively, for both kind of output signals, by switching the IF amplifier between the two modes, and by coupling one output of the tuner to ground in the asymmetrical mode.
In the symmetrical output mode, a signal is present on both outputs of the tuner (IF amplifier, mixer oscillator integrated circuit, respectively) to be processed further, while, in the asymmetrical output mode, an output signal is present on only one output, and the other output is coupled to ground.
In another embodiment of the invention, by using a switchable IF amplifier, the amplifier itself is switched between the two modes.
In a further embodiment of the invention, the IF amplifier comprises two amplifying means, one for the symmetrical mode and one for the asymmetrical mode, and the control means controls which amplifying means operative.
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RF9906—1995 Designer's handbook, RF Micro Device Inc., 1995.
Crand Olivier
Wink Meye
Biren Steven R.
Chow C.
Hunter Daniel
U.S. Philips Corporation
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