Disclosed examples include digital isolator modules, isolation circuitry and low-loss multi-order bandpass filter circuits, including a capacitive coupled galvanic isolation circuit with first and second coupling capacitors individually including a first plate and a second plate, and a bond wire connecting the first plates of the coupling capacitors, a first circuit with a first inductor coupled to form a first resonant tank circuit with a first parasitic capacitor associated with the second plate of the first coupling capacitor, and a second circuit with a second inductor coupled to form a second resonant tank circuit with a second parasitic capacitor associated with the second plate of the second coupling capacitor.

A package for a tunable filter is disclosed. In an embodiment, the tunable filter includes a substrate having a first interconnection plane and a semiconductor device assembled on the substrate in a first component plane, the semiconductor device electrically connected to the first interconnection plane and containing tunable passive components. The filter further includes a control unit arranged in the first component plane, a dielectric layer arranged above the first component plane, a second component plane arranged on the dielectric layer and discrete passive devices arranged in the second component plane and interconnected with the semiconductor device, wherein the tunable passive components are tunable by the control unit.

An analog time delay filter circuit including a first delay circuit block arranged in a modular layout, having a first time delay filter, a first input, a first output, and first and second pass-throughs; and a second delay circuit block arranged in the same modular layout, having a second time delay filter, a second input, a second output, and third and fourth pass-throughs.

A high-frequency front end circuit includes a fixed frequency filter and an interference-wave suppression variable filter. The fixed frequency filter attenuates a high-frequency signal outside a specific frequency band. The interference-wave suppression variable filter attenuates a high-frequency signal in at least one used communication channel, among used communication channels that are used by a system and that causes an interference wave occurring in a neighbor frequency domain including a wireless communication channel.

The present invention discloses an ultra wide band fixed phase shifter based on a capacitive load, which includes N physically separated phase shift units, and each phase shift unit includes an orthocoupler, first and second transmission lines, and first and second capacitive loads, wherein the orthocoupler includes an input end, a coupling end, a direct-connection end and an isolation end, one end of the first transmission line serves as a signal input end of the phase shift unit and the other end is connected with the input end of the orthocoupler, one end of the second transmission line serves as a signal output end of the phase shift unit and the other end is connected with the isolation end of the orthocoupler; one end of the first capacitive load is connected with the coupling end of the orthocoupler and the other end is grounded; one end of the second capacitive load is connected with the direct-connection end of the orthocoupler and the other end is grounded. The ultra wide band fixed phase shifter based on a capacitive load has compact structure, small area occupation and small insertion loss, does not need extra power supply and logical control, and can be widely applied.

A time delay filter comprising a substrate; four coupled LC resonators, each having a coupling point; a first capacitor that electrically couples the first coupling point to the second coupling point; a second capacitor that electrically couples the second coupling point to the third coupling point; and a third capacitor that electrically couples the third coupling point to the fourth coupling point; the filter group delaying a signal output at the fourth coupling point relative to a signal input at the first coupling point.

A filter circuit includes: a first element that is a first capacitor or a first inductor connected in series between input and output terminals; a second element that is connected in parallel to the first element between the input and output terminals, is a second inductor when the first element is the first capacitor, and is a second capacitor when the first element is the first inductor; a third element that is connected in parallel to the first element and in series with the second element between the input and output terminals, is a third inductor when the first element is the first capacitor, and is a third capacitor when the first element is the first inductor; and an acoustic wave resonator having a first end coupled to a first node between the second element and the third element and a second end coupled to a ground terminal.

A first series arm LC filter circuit includes a capacitor and an inductor connected in series to provide a series circuit between a first connection terminal and a second connection terminal, a capacitor connected in parallel to the series circuit, and an inductor and a variable capacitor connected in parallel between a connection point of the capacitor and the inductor and a ground potential. A first parallel arm LC filter circuit is connected between the first connection terminal and the ground potential. A second parallel arm LC filter circuit is connected between the second connection terminal and the ground potential. The inductor is directly connected to the second connection terminal or is connected to the second connection terminal with another inductor interposed therebetween.

A multilayer filter (1) includes an element body (2) formed by stacking a plurality of insulator layers (10), and an input terminal T.sub.IN (5), a first output terminal T.sub.OUT1 (9), and a ground terminal G (4, 8) arranged on outer surfaces of the element body (2), a first LC resonance circuit (RC2) provided in a line (S1) connecting the input terminal T.sub.IN (5) to the first output terminal T.sub.OUT1 (9) and including a first inductor (L2) and a first capacitor (C2), and an open inductor (L.sub.OPEN) having one end connected to the ground terminal (G) and the other end open are provided in the element body (2), and the open inductor (L.sub.OPEN) is arranged to face the first output terminal T.sub.OUT1 (9) or the first inductor (L2).

In a filter arrangement comprising a frequency filter (F) that has a bad or non-ideal ground connection (GC1, 2, 3, 4, 5, 6, 7), the defects arising from bad ground are compensated by a capacitance (CC) coupled in parallel to the frequency filter. The value of the capacitance is chosen between 1 and 50 fF. The filter arrangement may be a receiving filter (RF) in a duplexer (DU).