US 2017/0288632 A1 · VARIABLE FILTER CIRCUIT, RF FRONT END CIRCUIT AND COMMUNICATION DEVICE

Abstract

Provided is a variable filter circuit that can control the bandwidth and center frequency of a pass band, can realize steep attenuation characteristics in bands close to the pass band, and enables the total number of variable reactance units to be reduced. A variable filter circuit includes an inductor (Ls1) and a capacitor (Cs1), which are connected in series between a first input/output terminal (P1) and a second input/output terminal (P2), and resonators (Re_p1, Re_p2, Re_p3, Re_p4) and variable capacitors (Cc1, Cc2, Cc3, Cc4), which are connected in series between two ends of the inductor (Ls1) and the capacitor (Cs1) and ground connection terminals.

Claims11

Dependent claims

A variable filter circuit comprising:

a plurality of reactance elements that are connected in series between a first terminal and a second terminal;
and
a plurality of parallel arms, wherein each one of the plurality of parallel arms is connected between an end of at least one of the plurality of reactance elements and a ground terminal and comprises:
a resonance circuit;
and
a variable reactance connected in series with the resonance circuit,
wherein the plurality of reactance elements includes a capacitor having a capacitive reactance in a first frequency band and an inductor having an inductive reactance in a second frequency band.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application

15/492,190Filed 20 Apr 2017

Priority

JP 2014-22908511 Nov 2014

Published

5 Oct 2017

Term ends

Not estimatedThe source records don’t support an estimate.

Classification17 codes

H03H 7/12
Frequency selective two-port networks: bandpass or bandstop filters with adjustable bandwidth and fixed centre frequency
H03F 1/565
Modifications of input or output impedances, not otherwise provided for: using inductive elements
H03F 3/189
Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements: high-frequency amplifiers, e.g. radio frequency amplifiers
H03F 3/24
Power amplifiers, e.g. Class B amplifiers, Class C amplifiers: of transmitter output stages

Variable filter circuit, rf front end circuit and communication device

Life of this patent

Variable filter circuit, rf front end circuit and communication device

Life of this patent

Abstract

Claims11