Abstract:
A radio frequency (RF) power amplifier circuit includes an input and an output. A power amplifier transistor has a first terminal connected to the input, a second terminal connected to the output, and a third terminal defined by a degeneration inductance. A first capacitor is connected to the third terminal of the power amplifier transistor, along with a negative capacitance circuit connected in series with the first capacitor. The negative capacitance and the first capacitor define a series resonance at a predefined operating frequency band, which shunts the degeneration inductance of the third terminal.
Abstract:
An electronic circuit for imitating a capacitor with a controllable capacitance comprises a chain (CHN) of at least two differential pairs (DF1-DF3), the tail of each differential pair (DF1-DF3) being connected to a reference terminal (GND) via a respective separate current source (I1-I3). Each differential pair comprises a first and a second input. All the first inputs of the differential pairs (DF1-DF3) are connected to a signal terminal (CPVR) of the electronic unit. All the second inputs of the differential pairs (DF1-DF3) are interconnected via means (SPMNS) for supplying separate DC voltages between the second inputs of the differential pairs (DF1-DF3). Between the signal terminal (CPVR) and the reference terminal (GND) a capacitance is formed which is the sum of the input capacitances of the differential pairs (DF1-DF3). The capacitance is determined by the amount of charge per unit of voltage which is delivered to the first inputs of the differential pairs (DF1-DF3). If the separate DC voltages between the second inputs of the differential pairs (DF1-DF3) increase, then said amount of charge will decrease and as a consequence the capacitance will decrease. Thus the capacitance can be varied in that said separate DC voltages are varied.
Abstract:
Methods and apparatuses, including computer program products, are provided for filtering. In some example embodiments, there is provided an apparatus (400) including a first differential amplifier (405A) including a first positive input (407A), a first negative input, and a first output (412A), wherein the first positive input is connected to the first output via at least a first capacitor (409A), and wherein the first negative input is connected to the first output via at least a first resistor; and a second differential amplifier (405B) including a second input (407B), a third input, and a second output (412B), wherein the second input is connected to the second output via at least a third resistor (416), wherein the third input is connected to the second output via at least a second capacitor, and wherein an input (490) is connected to the first positive input (407A) and the second input (407B) via at least a third capacitor (409B). Related apparatuses, systems, methods, and articles are also described.
Abstract:
The invention relates to an electronic device for controlling a controlled oscillator. The electronic device provides a control input for supplying a control signal for tuning the oscillating frequency of the oscillator. Further the electronic device provides a transconductor having a transfer function in the frequency range with a substantially first- order high frequency roll off characteristic. The transconductor is adapted to be coupled to a tank circuit (L0, C0) and to act as a variable capacitance, such that the control signal controls the value of the variable capacitance of the transconductor for tuning the oscillating frequency of the controlled oscillator.
Abstract:
Un circuit (10) possede une impedance d'entree variable qui est commandee par application d'un signal d'entree en courant continu. Le circuit d'impedance variable comprend une paire de condensateurs (12, 14) couples en serie avec une paire de diodes (32, 34). Les diodes sont rendues conductrices en reponse au signal de commande en courant continu pour cour-circuiter sensiblement les deux condensateurs en serie entre eux sur les bornes d'entree (7, 18) du circuit. Lorsqu'aucun signal de commande n'est applique sur le circuit, les diodes sont non conductrices, ce qui deconnecte les condensateurs des entrees du circuit. Par consequent, la composante de reactance de l'impedance d'entree du circuit varie en reponse au signal de commande en courant continu.
Abstract:
Es ist ein rauscharmes analoges Filter mit einstellbarer Filterfrequenz beschrieben, mit einem Schwingkreis, dessen Resonanzfrequenz (f o ) gleich der Filterfrequenz des Filters ist, der einen ersten Schaltungszweig (S1) aufweist, in dem ein erstes frequenzbestimmendes Element angeordnet ist, der einen parallel oder in Serie zu dem ersten Schaltungszweig (S1 ) geschalteten zweiten Schaltungszweig (S2) aufweist, in dem ein zweites frequenzbestimmendes Element angeordnet ist, wobei eins der frequenzbestimmenden Elemente eine Kapazität (C) und das andere eine Induktivität (L) ist, und einem in einen der beiden Schaltungszweige (S1 oder S2) eingesetzten Verstärker (OPV 1 oder OPV 2 ) mit einstellbarer Verstärkung (V L oder V C ), dessen Ausgang über das in diesem Schaltungszweig (S1 oder S2) angeordnete frequenzbestimmende Element mit dessen invertierendem Eingang verbunden ist, und der im Filterbetrieb eine über das in diesem Schaltungszweig (S1, S2) angeordnete frequenzbestimmende Element anliegende Spannung der eingestellten Verstärkung (V L oder V C ) entsprechend verstärkt und dadurch eine entsprechende Veränderung eines durch dieses frequenzbestimmende Element fließenden Stroms bewirkt.
Abstract:
The invention relates to an electronic device for controlling a controlled oscillator. The electronic device provides a control input for supplying a control signal for tuning the oscillating frequency of the oscillator. Further the electronic device provides a transconductor having a transfer function in the frequency range with a substantially first- order high frequency roll off characteristic. The transconductor is adapted to be coupled to a tank circuit (L0, C0) and to act as a variable capacitance, such that the control signal controls the value of the variable capacitance of the transconductor for tuning the oscillating frequency of the controlled oscillator.
Abstract:
The present application relates to energy harvesting. More particularly, the present application relates to harvesting energy from non-stationary, multi-frequency mechanical vibrations using a tunable electrical circuit. In an embodiment, an apparatus for converting vibrational energy to electrical energy is disclosed, the apparatus comprising: a vibrational energy harvester having a transducer for generating time-varying electrical signals in response to environmental vibration; at least one power storage device; a switching network operably coupled between the transducer of the vibrational energy harvester and the at least one power storage device, wherein the switching network includes a plurality of switching elements, each defining a switchable current path that is controlled by a control signal supplied to the respective switching element; and electronics configured to generate the control signals for supply to the switching elements of the switching network, the electronics configured to control the switching elements to synthesize a reactive load that corresponds to characteristics of the energy harvester.