Abstract: Apparatus are provided for voltage-controlled oscillators and related systems. An exemplary voltage-controlled oscillator includes a first variable capacitance element, a second variable capacitance element coupled between the first control voltage node and the third node, and an inductive element coupled between the variable capacitance elements to provide an inductance between the variable capacitance elements at an oscillation frequency of an oscillating signal at an output node. The first variable capacitance element is coupled between a first control voltage node and the output node, the second variable capacitance element is coupled to the first control voltage node, and a second inductive element is coupled between the second variable capacitance element and a second control voltage node.

Abstract: A semiconductor device is provided which can reduce a parasitic inductor and/or parasitic capacitance added to the wiring that couples spiral inductors and MOS varactors included in a VCO. An LC-tank VCO includes first and second spiral inductors, and first and second MOS varactors. As seen perpendicularly to the semiconductor substrate, the first and second MOS varactors are arranged in a region between the first spiral inductor and the second spiral inductor.

Abstract: There is provided a digitally controlled oscillator. The digitally controlled oscillator includes a resonance circuit unit generating a resonance signal according to an equivalent capacitance formed by a parallel connection between a first capacitance varied depending on a digital control code and a second capacitance varied depending on an inverted digital control code generated by inverting the digital control code, and preset inductance; and an oscillation circuit unit providing negative resistance to the resonance circuit unit and forming oscillation conditions in the resonance circuit unit.

Abstract: Capacitive adjustment in an RCL resonant circuit is typically performed by adjusting a DC voltage being applied to one side of the capacitor. One side of the capacitor is usually connected to either the output node or the gate of a regenerative circuit in an RCL resonant circuit. The capacitance loading the resonant circuit becomes a function of the DC voltage and the AC sinusoidal signal generated by the resonant circuit. By capacitively coupling both nodes of the capacitor, a DC voltage can control the value of the capacitor over the full swing of the output waveform. In addition, instead of the RCL resonant circuit driving a single differential function loading the outputs, each output drives an independent single ended function; thereby providing two simultaneous operations being determined in place of the one differential function.

Abstract: An AD converter includes a first oscillator outputting a first frequency in accordance with a reference voltage; a second oscillator outputting a second frequency in accordance with an input voltage; a first counter measuring the first frequency; a second counter measuring the second frequency; and a comparator comparing a measurement result of the first frequency and a measurement result of the second frequency and outputting a digital value in accordance with the input voltage.

Abstract: An LC oscillator is provided that achieves improved phase noise performance. A variable frequency oscillator includes a variable supply source, an oscillator tank circuit, a variable capacitance circuit comprising MOS switches, and an oscillator tank voltage common mode adjustment circuit. When the capacitance of the variable capacitance circuit is varied to vary an output frequency of the variable frequency oscillator, the common mode voltage is adjusted to reduce transitions of the MOS switches between an inversion state and a depletion state during excursions of an output signal through one cycle of oscillation.

Abstract: A substantially temperature-independent LC-based oscillator uses bias control techniques. Temperature independence may be achieved by controlling the harmonic frequency content of the output of the oscillator by controlling the amplitude. Amplitude control may be achieved by inserting a control mechanism in the feedback loop of the oscillator.

Abstract: An LC oscillator tank that generates a tank oscillation at a phase substantially equal to a temperature null phase. The oscillator further includes frequency stabilizer circuitry coupled to the LC oscillator tank to cause the LC oscillator tank to operate at the temperature null phase. In one aspect of the disclosure, a feedback loop may split the output voltage of the LC tank into two voltages having different phases, where each voltage is independently transformed into a current through programmable transconductors, The two currents may be combined to form a resultant current which is then applied to the LC tank. The phase of the resultant current is such that the LC tank operates at an impedance condition that achieves frequency stability across temperature.

Abstract: An oscillating device is provided that has several oscillators. Each oscillator has a capacitive inductive resonant circuit and a flow-through conduction circuit having a negative flow-through conduction. The inductive elements of the oscillators are mutually coupled. Each oscillator also has short-circuit or not short-circuit the capacitive element of the oscillator. The oscillating device also has a controllable commutating means arranged to activate one oscillator at a time.

Abstract: A semiconductor integrated circuit device includes a DCO and a storing unit that stores a temperature coefficient of an oscillation frequency and an absolute value of the oscillation frequency, which should be set in the DCO, corresponding to potential obtained from a voltage source that changes with a monotonic characteristic with respect to temperature.

Abstract: Provided is a signal generator. The signal generator includes an insulating substrate, a chip disposed on the insulating substrate and including an oscillator including a capacitance element determining a resonant frequency signal, and a plurality of conductive lines disposed on the same surface of the insulating substrate to be spaced apart from each other. At least one of the plurality of conductive lines is electrically connected with the oscillator and provides an inductance element determining the resonant frequency signal to the oscillator.

Abstract: A single-ended-to-differential mixer includes a differential pair amplifier, a passive current source, a cancellation sub-circuit, and a mixer. The differential pair amplifier is configured to receive a single-ended input signal. The differential pair amplifier includes a first input, a second input, a first output, and a second output. The passive current source is connected between (i) the differential pair amplifier and (ii) a reference potential. The cancellation sub-circuit is connected to each of the first input, the second input, the first output, and the second output of the differential pair amplifier. The cancellation sub-circuit is configured to at least partially cancel a non-linearity of the differential pair amplifier. The mixer is connected to each of the first output and the second output of the differential pair amplifier.

Abstract: There is provided a voltage controlled oscillator that is compact and can be manufactured at low cost. The voltage controlled oscillator is structured to include: a resonance part including a variable capacitance element and an inductance element, the variable capacitance element having a capacitance that varies according to a control voltage for frequency control input from an external part, and a series resonant frequency of the resonance part being adjusted according to the capacitance; an amplifying part amplifying a frequency signal from the resonance part; and a feedback part including a capacitance element for feedback and feeding the frequency signal amplified by the amplifying part back to the resonance part to form an oscillation loop together with the amplifying part and the resonance part, wherein the amplifying part is provided in an integrated circuit chip, and the resonance part and the capacitance element for feedback are formed as circuit components separate from the integrated circuit chip.

Abstract: A system and method for configuring a tunable inductor that minimizes Q factor are provided. The system and method comprise coupling a first inductance, a second inductance, a third inductance, a switch, and two port terminals. The first inductance and the third inductance are coupled between the switch and the port terminals. The second inductance is coupled between the port terminals or between the first and third inductance. The inductances are each disposed on at least one layer, wherein the first inductance is disposed beneath the second inductance and the third inductance is disposed on the same layer as the second inductance. The components are arranged such that toggling the switch tunes the inductance without adversely affecting the Q factor.

Abstract: The present invention relates to an oscillator arrangement, arranged for providing an oscillator output and phase noise detection and/or control of said oscillator output, the arrangement comprising a mixer (1) connected to a low-pass filter (2). The oscillator arrangement comprises a first oscillator (7) and a second oscillator (8), where the oscillators (7, 8) are inter-injection locked to each other by means of at least one coupling element (Q) in such a way that the oscillator output is acquired in quadrature automatically. The present invention also relates to a corresponding method.

Abstract: There are provided a variable inductor with little degradation in quality factor, and an oscillator and a communication system using the variable inductor. An inductance controller comprising a reactance device with a variable device value, such as, for example, a variable capacitor, is connected to a secondary inductor, magnetically coupled to a primary inductor through mutual inductance. The inductance controller is provided with an inductance control terminal for receiving a control signal for controlling capacitance of the variable capacitor. Inductance of the primary inductor is varied by varying the capacitance by the control signal.

Abstract: A circuit includes first and second transconductance stages each having an input to receive a signal, and a current combiner circuit coupled to outputs of the first and second transconductance stages. The current combiner circuit forms a path from the first transconductance stage to (i) one of a plurality of output paths or (ii) multiple output paths of the output paths. The current combiner circuit severs the second transconductance stage from the output paths when the first transconductance stage forms a path to one of the output paths. The current combiner circuit forms a path from the second transconductance stage to the multiple output paths when the first transconductance stage forms a path to the multiple output paths. The current combiner circuit couples current from the first transconductance stage to (i) a first output path or a second output path or (ii) both the first and second output paths.

Abstract: An oscillator circuit comprises a push-push oscillator and a differential output, comprising a first and a second output circuit. The push-push oscillator has a first and a second branch. Each of the first and second branch comprises an own voltage divider branch of a common bridge circuit. Each of the first and second voltage divider branches comprises an own pair of micro-strip lines connected in series. Each of the first and second voltage divider branches has an own tap. Both taps are connected to each other by at least one of a first capacity and a micro-strip line. The differential output comprises a first and a second output terminal. The first output terminal is connected via the first output circuit to a first node. The second output terminal is connected via the second output circuit to a second node. Each of the first and second nodes of the push-push oscillator is a common node of both of the first and the second branches.

Abstract: In described embodiments, a wide toning-range (WTR) inductive-capacitive (LC) phase locked loop (PLL) provides for a large range of differing oscillation frequencies with a set of individual LC voltage controlled oscillator (VCO) paths. The output of each individual wide range LCVCO path is provided to a multiplexor (MUX), whose output is selected based on a control signal from, for example, a device controller. Each of the set of individual wide range LCVCO paths includes a switch that couples the LCVCO to a loop filter of a voltage tuning module, wherein each switch also receives the control signal to disable or enable the LCVCO path when providing the output signal from the MUX. Each switch is configured so as to minimize leakage current drawn by the LCVCO when disabled, and to reduce or eliminate effects of input capacitance of each dormant LCVCO to the loop dynamics of the PLL.

Abstract: The present application discloses a voltage-controlled oscillator device and a method of correcting the voltage-controlled oscillator. The voltage-controlled oscillator device comprises predistortion module, configured to predistort an input voltage to obtain a predistorted voltage; and a voltage-controlled oscillator, configured to generate an output signal with a corresponding oscillation frequency according to the predistorted voltage, wherein the predistortion module corrects a non-linear characteristic of the voltage-controlled oscillator, so that there is a linear relationship between the input voltage and the oscillation frequency of the output signal. The voltage-controlled oscillator device may be applied to a phase-locked circuit in a communication system.

Abstract: To provide a voltage controlled oscillator having small size and capable of obtaining a low phase noise characteristic over a large span of adjustable range of frequency. A quartz crystal having a characteristic (dielectric loss tangent: tan ?) better than that of fluorocarbon resin, LTCC or the like conventionally used as a substrate of a resonance part, and on which a fine pattern of metal film can be formed through a photolithography method, is used as a quartz-crystal substrate, and a conductive line is formed on the quartz-crystal substrate to form an inductance element in the resonance part. Accordingly, since the resonance part having a high Q value can be formed, it is possible to obtain a voltage controlled oscillator having small size and low loss over a wide frequency range.

Abstract: An apparatus includes a first conductive loop coupled to conduct a first current and a second conductive loop coupled in parallel with the first conductive loop and further coupled to conduct a second current. A first conductive portion forms a part of the first conductive loop and the second conductive loop. The first conductive portion is coupled to conduct the first current and the second current. In at least one embodiment of the apparatus, the first conductive loop and the second conductive loop are planar inductors formed in a conductive layer on a substrate of an integrated circuit.

Abstract: A resonator arrangement has a conductive, semi-open outer housing, at an interior of which a conductive bar is provided disposed coaxially to the housing. At one end of the bar in a direction of a housing bottom, the bar has a die and, together with a dielectric and the housing bottom, forms a capacitor. The bar is short-circuited to the housing at another end, so that the bar and housing together form an LC oscillator circuit. Also disclosed is a method for analyzing a sample using a resonator arrangement.

Abstract: A variable inductor includes: a first inductor having two ends connected to a first terminal and a second terminal; a second inductor having two ends connected to the first terminal and the second terminal; a first node provided on the first inductor; a second node provided on the second inductor; and a switch element that switches between a conductive state and a non-conductive state between the first node and the second node.

Abstract: An integrated circuit is described. The integrated circuit includes a global positioning system core that generates a GPS clock signal using an inductor-capacitor voltage controlled oscillator. The integrated circuit also includes a transceiver core configured to use the GPS clock signal. The transceiver core may not include a voltage controlled oscillator.

Abstract: A receiver is provided. The receiver includes a differential amplifier amplifying differential input signals input to input terminals and outputting differential output signals through output terminals and an oscillator connected to the output terminals of the differential amplifier. The differential amplifier and the oscillator operate alternatively in response to an enable signal.

Abstract: This disclosure relates to a programmable wideband, LC Tuned, Voltage Controlled Oscillator with continuous center frequency select, and independent configuration of amplitude and tuning gain. The programmability can be via on chip non-volatile memory, or through data shifted into the part and stored via a data bus.

Abstract: The present invention provides an oscillator and a communication system using the oscillator, in particular, an LC oscillator adapted to lessen phase noise deterioration due to harmonic distortions and increase the amplitude of oscillation, thereby having a favorable low phase noise characteristic. The oscillator comprises at least one voltage to current converter consisting of a transistor and a resonator comprising two LC tanks consisting of a pair of conductive elements and inductive elements. A feedback loop is formed such that an output terminal of the voltage to current converter is connected to the resonator and a current input to the resonator is converted to a voltage which is in turn fed back to an input terminal of the voltage to current converter. Inductive elements constituting the two LC tanks constituting the resonator are mutually inductively couple and a coefficient of the mutual induction is about ?0.6.

Abstract: In a dual-hand capable voltage-controlled oscillator (VCO) device at least two voltage-controlled oscillator units (VCO1, VCO2) are coupled via a reactive component (A) and each said at least one voltage-controlled oscillator unit (VCO1, VCO2) further being connected to at least a respective external switching device (B1, B2) adapted to control an operating frequency of the (VCO) device.

Abstract: This invention provides a voltage-controlled oscillator, comprising a first voltage-controlled oscillator circuit and a second voltage-controlled oscillator circuit. The first voltage-controlled oscillator circuit comprises a plurality of inductors, a plurality of variable capacitors, and a plurality of MOS transistors. The circuit configuration of the second voltage-controlled oscillator circuit is symmetrical to that of the first voltage-controlled oscillator circuit. The inductors of the first voltage-controlled oscillator circuit are cross-coupled to the inductors of the second voltage-controlled oscillator circuit.

Abstract: An inductor architecture for resonant clock distribution networks is described. This architecture allows for the adjustment of the natural frequency of a resonant clock distribution network, so that it achieves energy-efficient operation at multiple clock frequencies. The proposed architecture exhibits no inductor overheads. Such an architecture is generally applicable to semiconductor devices with multiple clock frequencies, and high-performance and low-power clocking requirements such as microprocessors, ASICs, and SOCs. Moreover, it is applicable to the binning of semiconductor devices according to achievable performance levels.

Abstract: An oscillator circuit with a voltage booster includes separated coils to oscillate and boost the input direct current voltage. The two coils are wound in opposite directs and magnetically coupled to one another. One of the coils is in series with a capacitor to form a LC oscillator. The circuit enables changing the frequency of oscillation by changing the number of turns on the coil in series with the capacitor or by changing the value of the capacitor. The output voltage level can be changed by changing the number of turns on the remaining coil.

Abstract: A first wiring layer and a plurality of second wiring layers having a thickness smaller than the first wiring layer are stacked on the semiconductor substrate. An oscillator circuit has an inductor formed by the plurality of second wiring layers. The inductor oscillates at a frequency at which the inductor and a parasitic capacitance of an inverter circuit resonate. A drain of an n-type MISFET and a drain of a p-type MISFET of the inverter circuit are connected to each other, and an output of the inductor is connected to a connection point of those drains.

Abstract: A temperature-compensated oscillator includes a temperature compensation circuit adapted to output a temperature compensation voltage, a voltage-controlled oscillation circuit on which temperature compensation is performed based on the temperature compensation voltage, a switch circuit adapted to perform ON/OFF control on power supply to the temperature compensation circuit, and a sample-and-hold circuit adapted to perform switching control between an ON state of outputting the temperature compensation voltage to the voltage-controlled oscillation circuit while being connected to the temperature compensation circuit and holding the temperature compensation voltage output from the temperature compensation circuit when the power is supplied to the temperature compensation circuit, and an OFF state of outputting the temperature compensation voltage held to the voltage-controlled oscillation circuit while cutting connection to the temperature compensation circuit when the power supply to the temperature compensat

Abstract: To provide a voltage controlled oscillator capable of being treated as a lumped constant circuit, having small size and capable of obtaining an oscillation frequency in a high frequency band. A resonance part in a voltage controlled oscillator has variable capacitance elements whose electrostatic capacitance varies in accordance with a control voltage for frequency control input from the outside and an inductance element, an amplifying part amplifies a frequency signal from the resonance part, and a feedback part, having feedback capacitance elements, forms an oscillation loop together with the amplifying part and the resonance part by making the frequency signal amplified in the amplifying part to be fed back to the resonance part. Further, the resonance part and the feedback part are provided on a quartz-crystal substrate.

Abstract: A voltage controlled oscillator circuit comprises a VCO resonator circuit having a first plurality of varactors for varying a frequency of the VCO resonator circuit, the VCO resonator circuit being symmetrical with respect to VCO circuit ground and providing a signal having a frequency, the frequency depending on a tuning voltage applied to the first plurality of varactors, and a second plurality of varactors for compensating a drift of the frequency depending on a compensation voltage, a temperature sensor circuit sensing an ambient temperature of the VCO resonator circuit and providing a temperature dependent signal, and a temperature compensation circuit providing the compensation voltage depending on the temperature dependent signal. Furthermore, a phase locked loop (PLL) circuit, an automotive radar device and a method for compensating a frequency drift of a VCO resonator circuit are presented.

Abstract: There is provided a voltage controlled oscillator using a Colpitts circuit capable of suppressing deterioration (decrease) in variable range (adjustable range) of an output frequency due to the influence of an inductance component on a conductive line, which connects a connection point between two capacitors of a feedback part and an emitter of a transistor. In a VCO using a Colpitts circuit, with respect to capacitors 22, 23 of a feedback part 2, a first feedback capacitance element (capacitor) 22 is disposed so as to directly couple a terminal for base (connection part 7) and a terminal for emitter on a base substrate 5, to which a terminal part 8 (T1) extending from a base of a transistor 21 and a terminal part 8 (T2) extending from an emitter of the transistor 21 are fitted, respectively, and a second feedback capacitance element (capacitor) 23 is disposed so as to directly couple the terminal for emitter and the terminal for grounding (ground electrode 51).

Abstract: A tunable resonant circuit includes first and second capacitors that provide a matched capacitance between first and second electrodes of the first and second capacitors. A deep-well arrangement includes a first well disposed within a second well in a substrate. The first and second capacitors are each disposed on the first well. Two channel electrodes of a first transistor are respectively coupled to the second electrode of the first capacitor and the second electrode of the second capacitor. Two channel electrodes of a second transistor are respectively coupled to the second electrode of the first capacitor and to ground. Two channel electrodes of the third transistor are respectively coupled to the second electrode of the second capacitor and to ground. The gate electrodes of the first, second, and third transistors are responsive to a tuning signal, and an inductor is coupled between the first electrodes of the first and second capacitors.

Abstract: A voltage controlled oscillator (VCO) securing a wide range of variable amount of oscillatory frequency is provided. In the VCO, a resistor R1 and a capacitor C1 are connected in series on a line of a crystal resonator and a control voltage supply terminal, a cathode of a variable-capacitance diode VD1 is connected between the R1 and the C1, and an anode of the VD1 is grounded. A parallel-connected circuit is disposed between the C1 and a port connected with the crystal resonator, the parallel-connected circuit including a variable-capacitance diode VD2 and a capacitor C3 connected in series, an expansion coil L1, and a Q dump resistor R6 which are connected in parallel. The parallel-connected circuit on an input side is grounded via a resistor R4, and a point between the R1 and the C1 and a point between the VD2 and the C3 are connected via a resistor R5.

Abstract: A dual positive-feedbacks voltage controlled oscillator includes an oscillation circuit and a cross coupled pair circuit. The oscillation circuit includes a first transistor, a second transistor, an inductor and a plurality of capacitors. The gates of the first and second transistors are opposite to each other and coupled to two points of the inductor. The inductor and the capacitors are formed as a LC tank. The cross coupled pair circuit includes a third transistor and a fourth transistor. The gates of the third and fourth transistors are cross coupled to two points of the inductor. Thereby, the gate of the third transistor is coupled to the gate of the second transistor; the gate of the fourth transistor is coupled to the gate of the first transistor; the drain of the third transistor is coupled to the source of the first transistor; and the drain of the fourth transistor is coupled to the source of the second transistor.

Abstract: Provided is a transformer-based oscillator which is suited to oscillate frequencies in multiple bands. An oscillator includes a transformer resonance unit and a plurality of complementary transistors. The transformer resonance unit includes a primary coil and a secondary coil corresponding to the primary coil. The plurality of complementary transistors have gates and drains between which both ends of the transformer resonance unit are respectively connected. Thus, the oscillator may operate in a differential mode or common mode according to the phase of the transformer resonance unit. Also, a complementary transistor constituting a multiband oscillation loop may be independently connected to both ends of the transformer resonance unit, and an oscillation loop of at least one band may be selected out of a multiband oscillation loop using a switch unit. Thus, the oscillator may be suited to oscillate resonance frequencies in multiple bands.

Abstract: A circuit includes an oscillator circuit including a first oscillator and a second oscillator. The first and the second oscillators are configured to generate signal having a same frequency and different phases. A transmission line is coupled between the first and the second oscillators.

Abstract: In one embodiment, a circuit comprises a first inductor-capacitor based voltage-controlled oscillator (LCVCO) generating a first periodic signal with a first frequency and a first phase and a second LCVCO generating a second periodic signal with a second frequency and a second phase, and the second phase is offset relative to the first phase by a 90 degrees offset.

Abstract: The present invention concerns a device having a first and a second differential oscillators (1, 2; 1?2?) coupled to and in quadrature-phase with each other, comprising first and second resonant electronic means (L1, C1, C2; L2, C3, C4) respectively, which are apt to provide, respectively on first two and second two terminals (NODE—1, NODE—2; NODE—3, NODE 4), first two and second two oscillating signals (VNODE—1, VNODE—2; VNODE—3, VNODE—4), said first two oscillating signals (VNODE—1, VNODE—2) being in phase opposition to each other and in quadrature-phase with said second two oscillating signals (VNODE—3, VNODE—4), the device being characterised in that it comprises first generator electronic means (M13-M24) apt to detect first instants of passage through a first reference value of each one of said first oscillating signals (VNODE—1, VNODE—2) and to generate first power supply pulses for said second resonant electronic means (L2, C3, C4) in second instants, and in that it comprises second generator electroni

Abstract: The disclosure relates to an oscillator for use in generating frequencies in a frequency synthesizer, comprising: a first inductor element forming a metal trace loop with at least one turn, and a first capacitive circuit arranged to form a first resonance circuit with the first inductor element and being connected to the first inductor element through at least one first connection terminal, wherein the first capacitive circuit comprises at least one capacitive element and an electrical components arrangement arranged to establish and maintain an oscillation.

Abstract: A digitally controlled oscillator provides high resolution in frequency tuning by using a digitally controlled capacitive network that includes a tunable capacitive circuit, a first capacitor and a second capacitor. The tunable capacitive circuit generates a variable capacitance according to a digital control word. The first capacitor is coupled in an electrically parallel configuration with the tunable capacitive circuit. The second capacitor is coupled in an electrically serial configuration with a combination of the first capacitor and the tunable capacitive circuit. The first capacitor and the second capacitor are sized such that an effective capacitance of the digitally controlled capacitor network has a step size that is a fraction of a step size of the variable capacitance in response to an incremental change in the digital control word.

Abstract: An integrated circuit includes an inductor-capacitor (LC) tank circuit coupled with a feedback loop. The LC tank circuit is configured to output an output signal having a peak voltage that is substantially equal to a direct current (DC) voltage level plus an amplitude. The feedback loop is capable of determining if the peak voltage of the output signal falls within a range between a first voltage level and a second voltage level for adjusting the amplitude of the output signal.

Abstract: A slew rate enhancing system is disclosed. The slew rate enhancing system includes a first switch and a second switch each having a control terminal, a first terminal, and a second terminal. The first terminals of the first and second switches receive a first signal of a differential signal pair. The control terminals of the first and second switches receive a second signal of the differential signal pair. A first output is connected to the second terminals of the first and second switches.

Abstract: A wideband digitally-controlled oscillator (DCO) is provided. The wideband DCO includes an active element which is driven by a first digital control signal; a single inductor which is connected to the active element in parallel, and comprises fixed inductance; and a plurality of capacitors which are connected to the single inductor in parallel, and vary operating frequency by being selectively turned on or off by a second digital control signal. Accordingly, the wideband DCO capable of operating in a wideband frequency range using a single inductor is provided, and if the wideband DCO is implemented using a single integrated circuit (IC) chip, the size of chip is reduced as the single inductor is used.

Abstract: Techniques are generally described herein related to filters including first operational transconductance amplifier (first OTA) and a second operational transconductance amplifier (second OTA). In some examples described herein, the first OTA and second OTA have substantially the same transconductance. The first and second OTAs can be configured to realize filters such as first-order all-pass filters, second-order all-pass filters, higher-order all-pass filters, and quadrature oscillators.