Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
267 words
Apparatus comprising: an amplifier having an input terminal for receiving an input signal and an output terminal at which an output signal is produced; a surface wave device having first and second input terminals, said first input terminal being connected for receiving an input signal, said second input terminal being connected to a point of AC ground potential, and an output terminal at which an output signal is produced, said surface wave device providing a predetermined bandpass filter characteristic for filtering said input signal to produce said output signal, said surface wave device exhibiting a capacitance C S between its input terminals; impedance transformation means coupled between said output terminal of said amplifier and said first input terminal of said surface wave device including an inductor L connected between said output terminal of said amplifier and said point of AC ground potential; and a capacitor C connected between said first input terminal of said first input terminal of said surface wave device and having a value selected so that the effective capacitance C E of the series combination of said capacitor C and said capacitance C S is substantially different from said capacitance C S and a resistance element directly connected between said first input terminal of said surface wave device and said point of AC ground potential without intervening elements having significant impedance in said passband of said surface wave device; said effective capacitance C E and said inductor L forming a parallel resonant circuit between said output terminal of said amplifier and said point of AC ground potential having a resonant frequency within said passband.
Claim 2
Dependent Claim
267 words
Apparatus comprising: an amplifier having an input terminal for receiving an input signal and an output terminal at which an output signal is produced; a surface wave device having first and second input terminals, said first input terminal being connected for receiving an input signal, said second input terminal being connected to a point of AC ground potential, and an output terminal at which an output signal is produced, said surface wave device providing a predetermined bandpass filter characteristic for filtering said input signal to produce said output signal, said surface wave device exhibiting a capacitance C S between its input terminals; impedance transformation means coupled between said output terminal of said amplifier and said first input terminal of said surface wave device including an inductor L connected between said output terminal of said amplifier and said point of AC ground potential; and a capacitor C connected between said first input terminal of said first input terminal of said surface wave device and having a value selected so that the effective capacitance C E of the series combination of said capacitor C and said capacitance C S is substantially different from said capacitance C S and a resistance element directly connected between said first input terminal of said surface wave device and said point of AC ground potential without intervening elements having significant impedance in said passband of said surface wave device; said effective capacitance C E and said inductor L forming a parallel resonant circuit between said output terminal of said amplifier and said point of AC ground potential having a resonant frequency within said passband.
Claim 3
Dependent Claim
25 words
The apparatus recited in claim 1 wherein said capacitance value C is in the same order of magnitude as said capacitance value C S .
Claim 4
Dependent Claim
21 words
The apparatus recited in claim 2, wherein: said capacitance value C is substantially equal to or less than 5C S .
Claim 5
Dependent Claim
42 words
The apparatus recited in claim 1 wherein: said amplifier includes feedback means coupled between said output and input terminals of said amplifier for applying at least a portion of said output signal of said amplifier to said input terminal of said amplifier.
Claim 6
Dependent Claim
59 words
The apparatus recited in claim 4 wherein: said amplifier includes a transistor having its base electrode connected to said input terminal of said amplifier; its emitter electrode connected to said point of AC signal ground; and its collector electrode connected to said output terminal of said amplifier; and a resistor connected between said collector electrode and said base electrode.
Claim 7
Dependent Claim
25 words
The apparatus recited in claim 5 wherein: said amplifier includes a second resistor connected between said emitter electrode and said point of AC signal ground.