Disclosed is a gallium arsenide (GaAs) enabled tunable filter for, e.g., 6 GHz Wi-Fi RF Frontend, with integrated high-performance varactors, metal-insulator-metal (MIM) capacitors, and 3D solenoid inductors. The tunable filter comprises a hyper-abrupt variable capacitor (varactor) high capacitance tuning ratio. The tunable filter also comprises a GaAs substrate in which through-GaAs-vias (TGV) are formed. The varactor along with the MIM capacitors and the 3D inductors is formed in an upper conductive structure on upper surface of the GaAs substrate. Lower conductive structure comprising lower conductors is formed on lower surface of the GaAs substrate. Electrical coupling between the lower and upper conductive structures is provided by the TGVs. The tunable filter can be integrated with radio frequency front end (RFFE) devices.

A transmission circuit including four transmission component sets for an Ethernet device is provided. Each transmission component set are coupled between an Ethernet connector and an Ethernet chip. Each transmission component set includes a transformer, two capacitors, and four transmission lines (TLs). The transformer includes four terminals and two center taps. Two diagonal terminals of the four terminals are coupled to a ground. The other two diagonal terminals of the four terminals are coupled to the Ethernet connector and, through one of the two capacitors, to the Ethernet chip via two of the four TLs, respectively. The two center taps are coupled to the Ethernet connector and, through the other one of the two capacitors, to the Ethernet chip via the other two of the four TLs, respectively.

A switch includes an input terminal, an output terminal, and a stack including transistors, such as, for example, field effect transistors, coupled in series, the stack being coupled between the input terminal and the output terminal. The switch also includes at least one switching element configured to be selectively operated in a conducting state or a non-conducting state, and at least one overvoltage protection element coupled to the stack by the at least one switching element. By way of example, the switch can implement a radio-frequency switch.

A composite electronic component includes a multilayered body in which a plurality of dielectric layers and a plurality of conductor layers are alternately stacked, a first resonant circuit including a first line and a first capacitor, the first line being formed of one or more first conductor layers of the conductor layers, the first capacitor including a first electrode formed of a plurality of second conductor layers of the conductor layers, and a second resonant circuit including a second line and a second capacitor, the second line being formed of one or more third conductor layers of the conductor layers, the second capacitor including a second electrode formed of the second conductor layers, the second conductor layers being located between the one or more first conductor layers and the one or more third conductor layers.

A circuit for blocking undesired input direct current of AC-coupled broadband circuits. The circuit includes a capacitor coupled to an input port and a common node. The input port receives a RF input signal. Additionally, the circuit includes a current source supplying a DC current to the common node leading a bias current to an output port. Further, the circuit includes a variable voltage source through an internal load and a close loop with an application circuit having an input load coupled to the output port to determine various bias voltages to control the bias current at the output port in association with a RF output signal that is substantially free of any input direct current originated from the RF input signal and is associated with an inherent low cut-off frequency independent of the various bias voltages.

A variable-frequency resonance circuit includes first and second input/output terminals and a resonance circuit portion. The resonance circuit portion includes a first inductor and first and second LC series circuits. The resonance circuit portion is connected between a ground and a transmission line that connects the first and second input/output terminals. The first LC series circuit includes a second inductor and a variable capacitor connected in series with each other. The second LC series circuit includes a third inductor and a fixed capacitor connected in series with each other. The first and second LC series circuits are connected in parallel between the first inductor and a ground. The first and second inductors are configured such that positive-coupling mutual inductance is produced therebetween.

A directional coupler includes a main line, a sub-line electromagnetically coupled with the main line, a coupled output terminal, plural filters, filter switching circuits, and plural filter protecting switches. Each of the filter switching circuits is able to connect a corresponding one of the plural filters to one end of the sub-line and to the coupled output terminal. Each of the filter protecting switches is directly connected to a corresponding end of a corresponding one of the plural filters and is able to switch between a connection state and a disconnection state. The connection state is a state in which the corresponding end of the corresponding one of the plural filters is connected to a reference potential. The disconnection state is a state in which the corresponding end of the corresponding one of the plural filters is disconnected from the reference potential.

The invention relates to a tunable, silicon-based negative-resistance circuit (10, 30) and to an active filter (50) for E-band frequencies (60 to 90 GHz). A base of a transistor (11) is connected to an on-chip inductive transmission line (13) which has a length of approximately a quarter-wavelength at a frequency of 83.5 GHz. The transmission line connects a DC voltage source (14) to the base terminal of the transistor (11) in order to bias the base. Another DC voltage source (15) is connected to the collector of the transistor (11) to bias the transistor. A capacitor (16) operatively bypasses or decouples the voltage source (15) in order to shunt high frequencies or alternating current (AC) signals to ground. The emitter terminal of the transistor (11) is connected to ground through a resistor (18) to limit the collector current (l.sub.e). The circuit gives rise to improved quality factor of resonators.

Systems and methods herein provide for a tunable resonator. In one embodiment, a tunable resonator includes a transmission line comprising at least two inductor segments and a tap between each of the at least two inductor segments. The resonator also includes one less switch than a number of the at least two inductor segments on the transmission line. Each switch is coupled to one of the taps. And, each switch is operable to decouple at least one of the at least two inductor segments in the transmission line by shunting at least a portion of the transmission line to ground to change a resonant frequency of the transmission line.

A filter combiner for a Doherty amplifier includes a first port with an impedance of Z0 configured to be connected to an output of a carrier amplifier; a second port with an impedance of Z0.Math.r/(1+r) configured to be connected to a load; a third port with an impedance of Z0.Math.r/(1+r) configured to be connected to a peak amplifier, wherein r is a power ratio for the carrier amplifier to the peak amplifier; and a fourth port with an impedance of Z0 configured to be connected to an output port of the Doherty amplifier. The first port is connected to the second port via a first network that is a lowpass filter and to the third port via a second network that is a lowpass filter which is configured to operate as a band stop filter upon loading the input or the output of the second network with a high impedance when the peak amplifier is off. The third port is connected to the fourth port via a third network that is a lowpass filter configured to operate as a band stop filter upon loading the input or the output of the second network with a high impedance when the peak amplifier is off. The fourth port is connected to the second port via a fourth network that is a lowpass filter.