An inductive synthesis circuit that mimics an ideal inductor over a wide range of inductance values, from less than 1 mH to more than 100 H, can be used in place of an inductor in any electrical circuit. One application of a synthesized inductor is in an integrated circuit in which it is impractical to construct a coil of wire. The inductive synthesis circuit is suitable for use in a calibration instrument for testing an inductance meter. The inductive synthesis circuit, together with a resistive synthesis circuit and a capacitive synthesis circuit, can be used to calibrate a multi-meter. Alternatively, the inductive synthesis circuit can be used to mimic an ideal inductor in a filter circuit that includes an inductor component, such as a high pass filter, a notch filter, or a band pass filter.

An integrated circuit may include one or more circuits coupled to capacitance multiplier circuitry. The capacitance multiplier circuitry may include a capacitor, fixed and tunable resistances, and a transconductance circuit. The tunable resistance can be adjusted to control the overall capacitance of the capacitance multiplier circuitry. The transconductance circuit may include a transistor having a drain terminal coupled to a first electrical component and a source terminal coupled to a second electrical component. The first electrical component may be a diode-connected transistor, a direct shorting wire, a resistor, an inductor, or a current source. The second electrical component may be a current source, a direct shorting wire, a resistor, an inductor, or another diode-connected device. Configured in this way, the capacitance multiplier circuitry can provide a large adjustable amount of capacitance without a voltage drop and without consuming a large amount of power.

A digital communication station includes a coupled inductor, driver circuitry, and a digital transceiver. The coupled inductor includes (1) a first winding connected between a first digital communication node and a first power node, (2) a second winding connected between a second digital communication node and a second power node, and (3) a third winding. The driver circuitry is configured to drive the third winding to increase respective inductance values of the first and second windings, and the digital transceiver is communicatively coupled to the first digital communication node and the second digital communication node.

A system and method for tuning a transistor-based circuit. The system includes a negative impedance converter circuit having a capacitor, a first transistor, and a second transistor. As a current travels through the capacitor, the first transistor and the second transistor each sample voltage at the capacitor and invert the voltage at an input of the negative impedance converter circuit. The negative impedance converter circuit also has a third transistor in series with the capacitor. The third transistor has a base voltage. Changing the base voltage of the third transistor changes the voltage sampled by the first transistor and the second transistor.

A circuit for controlling a capacitor having a capacitance adjustable by biasing, including an amplifier for delivering a D.C. bias voltage, having a feedback slowed down by a resistive and capacitive cell.

A filter circuitry (200) using an active inductor is disclosed. The filter circuitry (200) has a first terminal (In1/Out1) and a second terminal (In2/Out2). The filter circuitry (200) comprises a first transistor (M1) and a second transistor (M2). The filter circuitry (200) further comprises a first switch (S1), a second switch (S2), a first capacitor (C1), a second capacitor (C2) and a resistor (R). The first and second transistors (M1/M2) together with the resistor (R) and the first and second switches (S1/S2) are connected in a current mirror topology. The first and second capacitors (C1/C2) are connected at the first and second terminals of the filter circuitry (200) respectively. The filter circuitry (200) is configurable to either have the first terminal (In1/Out1) as input and the second terminal (In2/Out2) as output or have the first terminal (In1/Out1) as output and the second terminal (In2/Out2) as input by changing on-off states of the first and second switches. The transistors are interconnected in a current-mirror fashion. Depending on the switch position one of the transistors also acts as part of an active inductor such that the circuit functions as a low pass filter with a complex pole pair and a real pole. Depending on the switch position the LPF allows signal flow in either direction. For use in a TDD environment in combination with a passive mixer (420).

A combined mixer and filter circuitry is disclosed. The combined mixer and filter circuitry comprises a mixer comprising a first input, a second input and an output. The combined mixer and filter circuitry further comprises a filter comprising an active inductor and a first capacitor. The active inductor comprises a transistor having a first terminal, a second terminal and a third terminal and a resistor connected between the first terminal of the transistor and a voltage potential. The first capacitor is connected between the third terminal and a signal ground and the second terminal of the transistor is connected to the second input of the mixer.

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 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 combined mixer and filter circuitry is disclosed. The combined mixer and filter circuitry comprises a mixer comprising a first input, a second input and an output. The combined mixer and filter circuitry further comprises a filter comprising an active inductor and a first capacitor. The active inductor comprises a transistor having a first terminal, a second terminal and a third terminal and a resistor connected between the first terminal of the transistor and a voltage potential. The first capacitor is connected between the third terminal and a signal ground and the second terminal of the transistor is connected to the second input of the mixer.