A negative impedance circuit includes: a differential circuit stage; a positive feedback path from an output of the differential circuit stage to a first input of the differential circuit stage; and a negative feedback path from the output of the differential circuit stage to a second input of the differential circuit stage. The negative feedback path includes a first transistor, and a unitary gain path from the output of the differential circuit stage to the second input of the differential circuit stage, the unitary gain path coupled to ground via a reference impedance. The positive feedback path includes a second transistor. The first and second transistors are coupled in a current mirror arrangement and have respective control electrodes configured to be driven by the output of the differential circuit stage, where the negative impedance circuit causes a negative impedance at the first input of the differential circuit stage.

A negative impedance circuit includes: a differential circuit stage; a positive feedback path from an output of the differential circuit stage to a first input of the differential circuit stage; and a negative feedback path from the output of the differential circuit stage to a second input of the differential circuit stage. The negative feedback path includes a first transistor, and a unitary gain path from the output of the differential circuit stage to the second input of the differential circuit stage, the unitary gain path coupled to ground via a reference impedance. The positive feedback path includes a second transistor. The first and second transistors are coupled in a current mirror arrangement and have respective control electrodes configured to be driven by the output of the differential circuit stage, where the negative impedance circuit causes a negative impedance at the first input of the differential circuit stage.

A circuit includes a filter, a first inverter, and a second inverter. The filter is coupled to an input of the first inverter. The second inverter includes an input and an output. The input of the second inverter is coupled to the output of the first inverter. The output of the second inverter is coupled to the input of the first inverter. The filter includes a notch filter and a bandpass filter.

An oscillating element includes a substrate, negative resistance elements which are electrically connected to the substrate, antennas which are electrically connected one-to-one to each negative resistance element and which transmit or receive an electromagnetic wave, a pad electrically connected to a power supply source for supplying power to the antennas, and a conductor which electrically connects the pad and the antennas to each other. The conductor is constituted of a common wiring that is common to the antennas and individual wirings from the common wiring to each antenna. The individual wirings differ from each other with respect to a sectional area, resistivity, and a length in accordance with a position on the substrate of an antenna connected to each wiring to reduce a difference in wiring resistances caused based on a distance between the antenna connected to each wiring and the pad.

An oscillating element includes a substrate, negative resistance elements which are electrically connected to the substrate, antennas which are electrically connected one-to-one to each negative resistance element and which transmit or receive an electromagnetic wave, a pad electrically connected to a power supply source for supplying power to the antennas, and a conductor which electrically connects the pad and the antennas to each other. The conductor is constituted of a common wiring that is common to the antennas and individual wirings from the common wiring to each antenna. The individual wirings differ from each other with respect to a sectional area, resistivity, and a length in accordance with a position on the substrate of an antenna connected to each wiring to reduce a difference in wiring resistances caused based on a distance between the antenna connected to each wiring and the pad.

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.

A circuit includes a filter, a first inverter, and a second inverter. The filter is coupled to an input of the first inverter. The second inverter includes an input and an output. The input of the second inverter is coupled to the output of the first inverter. The output of the second inverter is coupled to the input of the first inverter. The filter includes a notch filter and a bandpass filter.

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.

A circuit includes a first operational amplifier having an inverting input and a non-inverting input, and a negative resistance circuit connected to the inverting input of the operational amplifier. The negative resistance circuit includes a second operational amplifier, a current source controlled by the second operational amplifier, and a cross-coupled transistor circuit having at least one transistor biased by a current produced by the current source.

An oscillating element includes a substrate, negative resistance elements which are electrically connected to the substrate, antennas which are electrically connected one-to-one to each negative resistance element and which transmit or receive an electromagnetic wave, a pad electrically connected to a power supply source for supplying power to the antennas, and a conductor which electrically connects the pad and the antennas to each other. The conductor is constituted of a common wiring that is common to the antennas and individual wirings from the common wiring to each antenna. The individual wirings differ from each other with respect to a sectional area, resistivity, and a length in accordance with a position on the substrate of an antenna connected to each wiring to reduce a difference in wiring resistances caused based on a distance between the antenna connected to each wiring and the pad.