US 2016/0105158 A1 · ELECTRONIC DEVICE INCLUDING FILTER

Abstract

An electronic device includes a main circuit connected between an input terminal and an output terminal, and an auxiliary circuit connected in parallel to the main circuit between the input terminal and the output terminal. The main circuit includes a filter having a first passband and a stopband. The auxiliary circuit has a passing characteristic that allows a signal having a frequency in a certain frequency band inside the stopband to pass through the auxiliary circuit. The main circuit is configured to output a main signal in response to an input signal. The auxiliary circuit is configured to output an auxiliary signal in response to the input signal. The main signal and the auxiliary signal contain phase components opposite to each other in the certain frequency band inside the stopband. This electronic device has an attenuation amount in the stopband.

Claims20

Dependent claims

An electronic device comprising:

an input terminal;
an output terminal;
a filter circuit connected between the input terminal and the output terminal and having a first phase characteristic, a first passband, and a first stopband, the filter circuit including a plurality of series arm resonators connected in series with one another along a signal line between the input terminal and the output terminal, and a plurality of parallel arm resonators connected between the signal line and a reference potential;
and
an auxiliary circuit connected in parallel with the filter circuit between the input terminal and the output terminal, the auxiliary circuit including a first capacitor element, a second capacitor element, and a resonator connected in series between the first capacitor element and the second capacitor element, the auxiliary circuit having an attenuation band within the first stopband and a second phase characteristic that is opposite to the first phase characteristic in the attenuation band.

2 more elements

An electronic device comprising:

a main circuit connected between a first signal terminal and a second signal terminal, the main circuit including a first filter connected between the first signal terminal and a third signal terminal and having a first passband, and a second filter connected between the third signal terminal and the second signal terminal and having a second passband that is different from the first passband, the main circuit having a first phase characteristic;
and
an auxiliary circuit connected in parallel with the second filter between the third signal terminal and the second signal terminal and having a second phase characteristic that is opposite to the first phase characteristic within at least one of the first passband and the second passband, the auxiliary circuit including a ladder filter including a series arm resonator and a parallel arm resonator, a first middle point between a first resonant frequency and a first anti-resonant frequency of the series arm resonator and a second middle point between a second resonant frequency and a second anti-resonant frequency of the parallel-arm resonator both being within one of the first passband and the second passband.

A high-frequency filter comprising:

a piezoelectric substrate;
first and second unbalanced signal terminals;
a pair of balanced signal terminals;
a main circuit connected between the first unbalanced signal terminal and the pair of balanced signal terminals, the main circuit including a first filter connected between the first unbalanced signal terminal and the second unbalanced signal terminal, and a second filter connected between the second unbalanced signal terminal and the pair of balanced signal terminals, the first filter having a first passband and the second filter having a second passband that is different from the first passband, the main circuit having a first phase characteristic;
and
an auxiliary circuit connected in parallel with the main circuit between the first unbalanced signal terminal and one of the pair of balanced signal terminals, the auxiliary circuit having an attenuation band within one of the first and second passbands, and a second phase characteristic that is opposite to the first phase characteristic in the attenuation band, and the auxiliary circuit, the first filter, and the second filter each including a plurality of surface acoustic wave elements formed on the piezoelectric substrate.

3 more elements

Dependencies are inferred from the claim text.

Electronic device including filter

Life of this patent

Electronic device including filter

Life of this patent

Abstract

Claims20