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US 5,521,554 AGranted
High-frequency band amplifier system
AssigneeAlps Electric Co., Ltd.
InventorMitsunari Okazaki
Life of this patent
Estimating the term…
Abstract
A high-frequency band amplifier system which is capable of containing the amount of ripple produced in the band passed by an SAW filter, and which is also capable of avoiding an increase in the noise factor. Such an amplifier system is constructed of a surface acoustic wave filter and a common-base connected transistor amplifier for amplifying the output from the surface acoustic wave filter.
Claims12
A high-frequency band amplifier system comprising:
- a surface acoustic wave filter having an output terminal;
- a common-base amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter and for generating an amplified output signal;
- and
- a differential amplifier including first and second transistors, each of the first and second transistors having a base connected to receive the amplified output signal;
- wherein the amplified output signal is transmitted to the first and second transistors in an imbalanced manner.
2 more elements
A high-frequency band amplifier system comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- a common-base amplifier having an emitter connected to the output terminal of the surface acoustic wave filter for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is less than an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter is greater than an input impedance of said common-base amplifier, thereby producing a second mismatched state;
- and
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state.
3 more elements
A high-frequency band amplifier system, comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- an amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is less than an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter is greater than an input impedance of said amplifier, thereby producing a second mismatched state;
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state;
- and
- wherein an inductance is connected to the output terminal of said surface acoustic wave filter in series with said amplifier so as to cancel an equivalent output capacitance of said surface acoustic wave filter and also to set the output impedance of said surface acoustic wave filter and the input impedance of said amplifier in a mismatched state.
4 more elements
A high-frequency band amplifier system, comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- an amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is less than an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter is greater than an input impedance of said amplifier, thereby producing a second mismatched state;
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state;
- wherein said amplifier is a common-base amplifier having an emitter connected to the output terminal of the surface acoustic wave filter;
- and
- wherein an input impedance at the emitter of said common-base amplifier is smaller than an impedance viewed from said emitter to said surface acoustic wave filter.
5 more elements
A high-frequency band amplifier system, comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- an amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is less than an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter is greater than an input impedance of said amplifier, thereby producing a second mismatched state;
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state;
- and
- wherein an inductance is connected to the output terminal of said surface acoustic wave filter in parallel with said amplifier so as to cancel an equivalent output capacitance of said surface acoustic wave filter and also to set the output impedance of said surface acoustic wave filter and the input impedance of said amplifier in a mismatched state.
4 more elements
A high-frequency band amplifier system, comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- an amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is less than an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter is greater than an input impedance of said amplifier, thereby producing a second mismatched state;
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state;
- and
- wherein an inductance is connected to the output terminal of said surface acoustic wave filter in series and in parallel with said amplifier so as to cancel an equivalent output capacitance of said surface acoustic wave filter and also to set the output impedance of said surface acoustic wave filter and the input impedance of said amplifier in a mismatched state.
4 more elements
A high-frequency band amplifier system comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- a common-base amplifier having an emitter connected to the output terminal of the surface acoustic wave filter for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is one-half of an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter and an input impedance of said common-base amplifier are in a second mismatched state;
- and
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state.
3 more elements
The high-frequency band amplifier system, comprising:
- a surface acoustic wave filter connected to a signal source and having an output terminal;
- and
- an amplifier connected to the output terminal for amplifying an output signal from said surface acoustic wave filter,
- wherein an internal impedance of said signal source is one-half of an input impedance of said surface acoustic wave filter, thereby producing a first mismatched state, and an output impedance of said surface acoustic wave filter and an input impedance of said amplifier are in a second mismatched state;
- wherein a mismatching loss produced by said first mismatched state is smaller than a mismatching loss produced by said second mismatched state;
- and
- wherein the input impedance of the amplifier is one-fourth of the output impedance of the surface acoustic wave filter.
4 more elements
Dependencies are inferred from the claim text.