A tunable impedance simulator and impedance multiplier circuit and a system for configuring a second generation voltage-mode conveyor circuit (VCII) as the tunable impedance simulator and impedance multiplier are described. The tunable impedance simulator and impedance multiplier circuit includes one VCII having a positive input terminal connected to a voltage source, a negative input terminal connected to the voltage source, and an impedance terminal Z.sub.0 . The impedance terminal Z.sub.0 can be either positive or negative. When the impedance terminal Z.sub.0 is positive, a positive active inductor, a positive capacitance multiplier, and a positive resistance multiplier may be implemented. When the impedance terminal Z.sub.0 is negative, a negative active inductor, a negative capacitance simulator, and a negative resistance simulator may be implemented.

A tunable impedance simulator and impedance multiplier circuit and a system for configuring a second generation voltage-mode conveyor circuit (VCII) as the tunable impedance simulator and impedance multiplier are described. The tunable impedance simulator and impedance multiplier circuit includes one VCII having a positive input terminal connected to a voltage source, a negative input terminal connected to the voltage source, and an impedance terminal Z.sub.0 . The impedance terminal Z.sub.0 can be either positive or negative. When the impedance terminal Z.sub.0 is positive, a positive active inductor, a positive capacitance multiplier, and a positive resistance multiplier may be implemented. When the impedance terminal Z.sub.0 is negative, a negative active inductor, a negative capacitance simulator, and a negative resistance simulator may be implemented.

An oscillation element that oscillates an electromagnetic wave includes a negative resistance element and a resonator including a first conductor and a second conductor, in which the negative resistance element and the resonator are arranged on a substrate, the negative resistance element is electrically connected to the first conductor and the second conductor, the first conductor and the second conductor are capacitively coupled to each other, and when a capacitance between the first conductor and the second conductor is set as C, an inductance of the first conductor and the second conductor is set as L.sub.1, a speed of the oscillated electromagnetic wave in vacuum is set as C.sub.0, a relative dielectric constant of the substrate is set as .sub.r, and a diagonal line length of the substrate is set as d, a series resonant frequency f.sub.1 of the resonator satisfies f.sub.1=1/{2(L.sub.1C)}, and f.sub.1<C.sub.0/[d{(1+.sub.r)/2}].

An oscillation element that oscillates an electromagnetic wave includes a negative resistance element and a resonator including a first conductor and a second conductor, in which the negative resistance element and the resonator are arranged on a substrate, the negative resistance element is electrically connected to the first conductor and the second conductor, the first conductor and the second conductor are capacitively coupled to each other, and when a capacitance between the first conductor and the second conductor is set as C, an inductance of the first conductor and the second conductor is set as L.sub.1, a speed of the oscillated electromagnetic wave in vacuum is set as C.sub.0, a relative dielectric constant of the substrate is set as .sub.r, and a diagonal line length of the substrate is set as d, a series resonant frequency f.sub.1 of the resonator satisfies f.sub.1=1/{2(L.sub.1C)}, and f.sub.1<C.sub.0/[d{(1+.sub.r)/2}].

A vibration controller includes: a piezoelectric element fixed to an object of control; and a quasi-inductor circuit and a negative resistance circuit connected in series to the piezoelectric element.

An impedance converter circuit achieves negative capacitance and/or negative inductance for radio frequency (RF) front end impedance matching for low noise amplifier (LNA) designs. The impedance converter circuit includes a first transistor coupled to a first RF input at a source of the first transistor. The impedance converter circuit also includes a second transistor coupled to a second RF input at a source of the second transistor. The second transistor is cross-coupled to the first transistor to form a cross-coupled pair of transistors. The cross-coupled pair of transistors is configured to generate a negative capacitance or a negative inductance based on a load impedance coupled to a drain of the first transistor and a drain of the second transistor.

Systems, apparatuses, and methods for implementing a negative resistance circuit for bandwidth extension are disclosed. Within a feedback path of a differential signal path, capacitors are placed on the inputs and outputs of a fully differential amplifier connecting to the differential signal path. In one embodiment, a circuit includes a fully differential amplifier and four capacitors. A first capacitor is coupled between a first signal path and a non-inverting input terminal of the amplifier and a second capacitor is coupled between the first signal path and a non-inverting output terminal of the amplifier. A third capacitor is coupled between a second signal path and an inverting input terminal of the amplifier and a fourth capacitor is coupled between the second signal path and an inverting output terminal of the amplifier. The first and second signal paths carry a differential signal.

A tank circuit (200) includes a tunable resonator subcircuit (210) having a first control input and having an effective parallel resistance that varies with tuning of the tunable resonator subcircuit (210). The tank circuit (200) further comprises a variable negative-resistance subcircuit (250) having a second control input and coupled in parallel to the tunable resonator subcircuit (210), where the variable negative-resistance subcircuit (250) is configured to provide a variable negative resistance, responsive to the control input, so as to increase the effective parallel resistance of the tank circuit (200).

An element which oscillates or detects terahertz waves includes a resonance unit including a differential negative resistance element, a first conductor, a second conductor, and a dielectric body, a bias circuit configured to supply a bias voltage to the differential negative resistance element, and a line configured to connect the resonance unit and the bias circuit to each other. The differential negative resistance element and the dielectric body are disposed between the first and second conductors. The line is a low impedance line in a frequency f.sub.LC of resonance caused by inductance of the line and capacitance of the resonance unit using an absolute value of a differential negative resistance of the differential negative resistance element as a reference.

An element which oscillates or detects terahertz waves includes a resonance unit including a differential negative resistance element, a first conductor, a second conductor, and a dielectric body, a bias circuit configured to supply a bias voltage to the differential negative resistance element, and a line configured to connect the resonance unit and the bias circuit to each other. The differential negative resistance element and the dielectric body are disposed between the first and second conductors. The line is a low impedance line in a frequency f.sub.LC of resonance caused by inductance of the line and capacitance of the resonance unit using an absolute value of a differential negative resistance of the differential negative resistance element as a reference.