30 results about "Colpitts oscillator" patented technology

A radio frequency identification device includes a transceiver having a resonant circuit, a rectifier, a charge pump, a state machine, and a transmitter. The resonant circuit includes an antenna and has a resonant frequency. The rectifier is coupled to the resonant circuit to provide a rectified signal in response to energy from the antenna. The charge pump is enabled in response to the rectified signal to provide a first logic signal. The state machine provides a second logic signal in response to the first logic signal. The transmitter includes an amplifier coupled to the resonant circuit to form a Colpitts oscillator that is enabled by the second logic signal to transmit a response signal for identifying the radio frequency identification device.

In wireless application there is made use of a quadrature oscillators that generate signals that are capable of oscillating at quadrature of each other. The quadrature oscillator is comprised of two differential modified Colpitts oscillators. A capacitor bank allows for the selection of a desired frequency from a plurality of discrete possible frequencies. The quadrature oscillator is further coupled with a phase-error detector connected at the point-of-use of the generated ‘I’ and ‘Q’ channels and through the control of current sources provides corrections means to ensure that the phase shift at the point-of-use remains at the desired ninety degrees.

A modulated Class E oscillator. In one embodiment, the modulated Class E oscillator may achieve high coil currents (about 1 A) and voltages (about 500 V) with low power components. Current may be injected when the oscillating current in the inductor passes through zero. A detector circuit may be used to trigger the current injection at the appropriate instant regardless of changes in the resonant frequency of the system. Its phase can be adjusted to compensate for propagation delays in the drive circuitry, while amplitude modulation is accomplished by switching in additional reactive conductance to increase the current injected into the tank circuit. Frequency modulation is accomplished in an alternate embodiment. The oscillator can also lock to an external reference signal and be phase modulated.

A CMOS single-ended frequency doubler with improved subharmonic rejection and low phase noise which allows a single ended reference signal to be utilized in a Balanced Colpitts oscillator. The input is reproduced with a 180-degree phase shift for the opposite Colpitts transistor. This is achieved by adding two PMOS transistors. One transistor is placed as a follower, which reproduces any voltage shift applied to its gate to its source. Another transistor is a matching transistor for balance. By applying the single-ended signal to the gate of the follower transistor, it is reproduced at the source. The rest of the circuit takes advantage of the summing of two period currents with a 180-degree phase shift. The present invention achieves superior performance for frequency doubling due to the squaring of the gate voltage in the corresponding drain current. As a result, the double frequency component is further enhanced.

Oscillation in which unwanted vibration (B mode) is surely suppressed while stable oscillation by principal vibration (C mode) is obtained is obtained. In a Colpitts oscillator including a piezoelectric vibrator, a transistor, and a first and second divided capacitive components, by inserting a feedback circuit formed by connecting a third capacitive component and a first inductor in series between a connection midpoint between the first capacitive component and the second capacitive component and an emitter of the transistor, inserting a second inductor in parallel with the second capacitive component, and setting the parallel resonance frequency of the second capacitive component and the second inductor in the vicinity of the oscillation frequency of the oscillator, the frequency band in which the negative resistance of the circuit side seen from the piezoelectric vibrator appears is set to a narrow band containing only a desired frequency to suppress unwanted vibration of the oscillator.

A low power balanced Colpitts oscillator circuit with improved negative resistance. The oscillator circuit comprises two cross-coupled Colpitts oscillators with a crystal oscillator connected between the two oscillators. A single current source can be used for both Colpitts oscillators since only one Colpitts needs a current source at a time. Using a single current source cuts the power consumption in half. Alternatively, a transistor in each Colpitts oscillator can act as a current source, which is turned on or off depending on the state of the Colpitts transistor. The two current sources are biased at a common level and matched to ensure the circuit remains symmetrical. An additional benefit of the present invention is that the negative resistance is directly improved.

A piezoelectric-vibrator series circuit including two series-connected piezoelectric vibrators to which stresses induced by a dynamic quantity are applied in opposite directions is used, and a Colpitts oscillator circuit is defined by the piezoelectric-vibrator series circuit and an amplifier circuit / load impedance circuit. A phase-difference-to-voltage converter circuit is provided to convert a phase difference between an output voltage of the oscillator circuit and a voltage at a piezoelectric-vibrator series node of the piezoelectric-vibrator series circuit into a voltage signal.

An oscillator outputs a sine wave with high purity capable of reducing phase noise. In a Colpitts oscillator circuit using a transistor (3) as an amplifying part, a quartz-crystal resonator (5) for waveform shaping is provided outside or inside an oscillation loop. A quartz-crystal resonator (1) for oscillation and the quartz-crystal resonator (5) for waveform shaping are formed, with an electrode pair (11, 12) and an electrode pair (51, 52) being provided on a common quartz-crystal piece (10). A separation distance between the electrode (11, (12)) of the quartz-crystal resonator (1) and the electrode (51, (52)) of the quartz-crystal resonator (5) is set large so that they are not elastically coupled, or even when they are elastically coupled, their coupling degree is weak, and an inductor causing parallel resonance with a parallel capacitance of the quartz-crystal resonator (5) is provided. And the quartz-crystal resonator (1) for oscillation and the quartz-crystal resonator (5) for waveform shaping can be replaced by an SAW harmonic oscillator using the same piezoelectric sheet construction.

A piezoelectric oscillator including a piezoelectric vibrator that vibrate at desired frequency; a first transistor for exciting the piezoelectric vibrator; a second transistor whose collector connects to an emitter of the first transistor, the second transistor being a base grounded type; a first capacitor connected between the emitter of the first transistor and ground; a series circuit comprising the piezoelectric vibrator and a second capacitor being connected between a base of the first transistor and an emitter of the second transistor, in which the first capacitor and a composition capacitance between base and emitter of the first transistor functions as a split capacitor for a feedback circuit of the Colpitts oscillator.

In a Colpitts quartz oscillation circuit, large negative resistance values are obtained in a high frequency band, and in the GHz band in particular. In a piezoelectric oscillator having a Colpitts oscillator, a voltage control circuit, and a coupling capacitor that couples the Colpitts oscillator and the voltage control circuit, an output of the voltage control circuit is feed back to a collector of the Colpitts oscillator via the coupling capacitor.

The invention discloses a chaotic signal generator based on a generalized memristive Colpitts oscillator, comprising a capacitor C 1 , capacitance C 2 , capacitance C 3 , inductance L, resistance R 1 , resistance R 2 , a bipolar transistor Q, and a generalized memristor M based on a memristive diode bridge. The chaotic signal generator based on the generalized memristor Colpitts oscillator of the present invention introduces the generalized memristor circuit based on the memristor diode bridge into the fourth-order Colpitts oscillator circuit, and can generate various chaotic phenomena by adjusting system parameters, so that It becomes a new type of chaotic signal generator. It has simple structure, strong stability, and remarkable chaotic characteristics, which can promote the development of chaotic systems.

A displacement sensor is provided. According to the present invention, a parallel resonant circuit (4) consisting of a coil (6) and condensers (8, 10) is installed in output of an NPN transistor (12),and output of the parallel resonant circuit (4) returns to input of the transistor (12), and a Colpitts oscillator circuit (2) is formed to be continuously oscillated. An output level of the transistor (12) is changed by a change in a position of a measured material toward the coil (6). A constant current source (26) continuously supplies a direct current to the coil (6). An RC low pass filter (30) detects a change in a direct current resistance value of the coil (6) from voltage drop due to a direct current flowing through the coil (6). A microcomputer (38) adjusts an output level of the transistor (12) is adjusted based on an output of the RC low pass filter (30).

A differential Colpitts voltage-controlled oscillator according to example embodiments includes a feedback circuit constituting a Colpitts oscillator structure, a negative resistance circuit including a first negative resistance transistor and a second negative resistance transistor cross-coupled to each other and connected to the feedback circuit, a resonance circuit including a first inductor and a variable capacitor connected to both ends of the first inductor to generate differential output signals base on outputs of the feedback circuit, and a phase noise reduction circuit coupled to the feedback circuit to remove phase noise.

The invention discloses a phase-shift processing based band-pass filtering oscillation system. The phase-shift processing based band-pass filtering oscillation system mainly comprises a signal transformation circuit, a signal amplification circuit connected with the signal transformation circuit, a band-pass filtering circuit connected with the signal amplification circuit, and a buffer circuit. The phase-shift processing based band-pass filtering oscillation system is characterized in that a phase-shift processing circuit is further arranged between the buffer circuit and the band-pass filtering circuit and comprises a phase-shift chip U1, a triode VT3, a triode VT2, a resistor R15, a polar capacitor C10 and the like, wherein one end of the resistor R15 is connected with a VCC+ pin of the phase-shift chip U1 while the other end of the resistor R15 is connected with an IN1 pin of the phase-shift chip U1, and a cathode of the polar capacitor C10 is connected with the IN1 pin of the phase-shift chip U1 after passing by a resistor R16 while an anode of the polar capacitor C10 is connected with an IN2 pin of the phase-shift chip U1. The phase-shift processing based band-pass filtering oscillation system has the advantages that by the aid of the phase-shift processing circuit, filtering stability of an oscillation circuit can be improved, and filtering incompleteness of the system due to instable voltage is avoided; meanwhile, an integrated chip LM741 which is high in sensitivity and cheap is adopted.

The invention discloses a Colpitts oscillator. The Colpitts oscillator depends on a near-zero threshold value MOS tube during oscillation starting and is designed by applying a substrate bias method or a grid bias method respectively, it is ensured that the MOS tube voltage gain required by circuit resonance is far greater than 4 according to the index response characteristic of the common-gate amplification coefficient of the near-zero threshold value MOS tube, and accordingly the Colpitts oscillator can achieve oscillation starting and oscillation maintenance under the condition of ultralow direct current input voltage and meet the requirements of a brain implant sensor.