41results about How to "Reduce 1/f noise" patented technology

A passive mixer for converting a radio frequency (RF) signal to an intermediary frequency (IF) signal or vice versa. The mixer comprises a voltage controlled mixing means for mixing a local oscillator signal with either an RF or IF signal. A bootstrapping technique is used for feeding back a low frequency component of the IF signal through a low-pass filter to the mixing means. The mixing means will follow low frequency variations of the IF signal, which will improve the linearity of the mixer.

The present invention provides a magnetic sensing device capable of stably sensing a signal magnetic field with high sensitivity by suppressing occurrence of a hysteresis to reduce 1/f noise. A magnetic sensing device has a stacked body including a pinned layer having a magnetization direction pinned to a predetermined direction (Y direction), a free layer having a magnetization direction which changes according to an external magnetic field and, when the external magnetic field is zero, becomes parallel to the magnetization direction of the pinned layer, and an intermediate layer sandwiched between the pinned layer and the free layer. Consequently, as compared with the case where the pinned layer and the free layer have magnetization directions which are orthogonal to each other when the external magnetic field is zero, variations in the spin directions of magnetic domains in the free layer can be reduced. In the case of passing read current, appearance of a hysteresis in the relation between a change in the external magnetic field and a resistance change can be suppressed. As a result, 1/f noise is suppressed and a signal magnetic field can be stably sensed with high sensitivity.

The invention discloses a high-precision polarized navigator, which comprises the following parts to form the polarized receiving system: first polarized lens cone, second polarized lens cone, third polarized lens cone and polarized lens cone, wherein the output direction of polarized receiving system contains light-beam deflecting device, polarized adjustment system and photoelectric detector array sequently, which connects lock-in amplifying circuit, logarithmic amplifying circuit, data gathering card and computer after the photoelectric detector array; the photoelectric detector array transmits the received two paths of polarized signal into electrical signal, which is disposed by computer to realize the navigation of moving object through logarithmic amplifying circuit and lock-in amplifying circuit. The invention simplifies the structure with good reliability and high precision, which is fit for real-time navigation of traffic tool and moving object.

The noise removing device for an image sensor according to the present invention is for reducing the noise in the output of the image sensor. The device comprises: a noise generator for generating the noise in common-mode with respect to the output of the image sensor; and a differential amplifier which amplifies the difference between the output of the image sensor and the output of the noise generator. By canceling the common-mode signals, 1/f noise, low-frequency noise, high-frequency noise, shot noise, beat noise and the like, which are asynchronous with the horizontal synchronizing signals, can also be reduced.

The invention provides a band gap voltage reference circuit, and belongs to the field of analog circuits. The band gap reference circuit comprises a first PMOS transistor, a second NMOS transistor, a third NMOS transistor, a fourth PMOS transistor, a fifth PMOS transistor, a sixth PMOS transistor, a first PNP audion, a second PNP audion, a capacitor C, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and an operational amplifier. According to the technical scheme, the influence of local oscillator noise and voltage noise on output voltages can be lowered, the precision of a reference voltage is improved, meanwhile, the area of a chip is considered, and the design complexity of the circuit is reduced.

The invention discloses an orthogonal inductance-capacitance voltage-controlled oscillator with low power consumption and low phase noise, which comprises two voltage-controlled oscillators VCO with the same structure, an MOS transistor NM4 in a diode connection mode and a low-pass RC filter LPF, wherein each VCO comprises an LC resonance network formed by an inductor and a distributed varactor structural circuit, a negative resistance differential pair transistors with upper P and lower N being complementary, a series coupling tube connected with the negative resistance differential pair transistors with upper P and lower N being complementary and tail current tube, and the negative resistance differential pair transistors with upper P and lower N being complementary are connected with the LC resonance network; the series coupling tubes in the two VCOs are connected; and the MOS transistor NM4 in the diode connection mode, the low-pass RC filter LPF and the tail current tubes in the two VCOs are sequentially connected to form a current mirror. The scheme disclosed by the invention has the characteristics of low power consumption, low phase noise, low phase error and high linear gain, and is applicable to phase-locked loop type frequency synthesizers.

The invention relates to a circuit of a deep-sea geomagnetic measuring instrument. The precision of the existing device is too low, thereby being lack of practical significance in the application of analyzing the geomagnetic micro-change of a small ocean bottom region. The circuit comprises a power supply circuit, a setting/resetting circuit, a sensing measuring circuit and a main control circuit, wherein, the sensing measuring circuit comprises a single-axis magnetoresistive sensor chip IC4, a dual-axis magnetoresistive sensor chip IC5, three same operational amplifier circuits 5, a high-precision AC chip IC6 and a voltage reference chip IC7. The main control circuit comprises a main control chip IC8, a gyroscope chip IC9, a level conversion chip IC10 and a reading/writing interface J1 of an SD card. The circuit adopts the magnetoresistive sensing technology to constitute a deep-sea geomagnetic measuring circuit and utilizes the characteristics of high sensitivity and low power consumption of the magnetoresistive sensors, thereby having simple circuit connection, reducing the noise by 1/f and improving the effective resolution.

A low noise voltage reference circuit is described. The reference circuit utilizes a bandgap reference component and may include at least one of a current shunt or filter to reduce high and low noise contributions to the output. Further modifications may include a curvature correction component.

The invention discloses a system and a method for reducing noise of a tunnel magnetoresistance sensor. The system comprises a coil-free shielding cylinder and a driving circuit, wherein the coil-freeshielding cylinder is made of a soft magnetic material with high magnetic conductivity; a to-be-processed TMR sensor is placed in the center of the coil-free shielding cylinder; the output end of theTMR sensor is connected with the input end of the driving circuit; the coil-free shielding cylinder is based on the supersaturation characteristic of a high-permeability soft magnetic material, and when alternating current is introduced, the shielding capability of the coil-free shielding cylinder changes at high frequency, so that a to-be-measured direct-current magnetic field of the TMR sensor is converted into a high-frequency alternating-current magnetic field, and 1/f noise of the TMR sensor is reduced; the driving circuit performs phase-sensitive detection and low-pass filtering on an output signal of the TMR sensor based on the reference signal, filters out a sum frequency signal, retains a difference frequency signal, and further filters out 1/f noise of the TMR sensor. According to the coil-free shielding cylinder, multiple turns of coils do not need to be wound, new noise cannot be introduced, and the noise reduction effect is good.

The invention discloses a combined oceanic electric field sensor and a matching test method thereof. The oceanic electric field sensor comprises a data acquisition station (1) for acquiring and storing electric field signals, a data transmission device (2) for transmitting electric field signals detected by electrodes (16 and 26) to the data acquisition station (1), electrode cabins (3 and 4) for installing a watertight connecting socket (5) and fixing the electrodes (16 and 26), the watertight connecting socket (5) for connection of the electrodes (16 and 26), and the electrodes (16 and 26) for detecting the electric field signals. The self noise of the combined oceanic electric field sensor is reduced, the measuring sensitivity of the electric field sensor is improved, repeated usage of the electrodes is achieved, and the using cost of the combined oceanic electric field sensor is reduced.

The invention discloses a pixel circuit of an infrared detector and a driving method, and belongs to the field of infrared detector circuit design. The pixel circuit comprises an integral control circuit, a signal transmission circuit, a reset circuit, a gating read-out circuit and an integral capacitor. According to the pixel circuit of the infrared detector and the driving method provided by theinvention, the reset voltage and the signal voltage can be read out in a time-sharing manner in a short time interval of the same frame, and thermal noise signals contained in two times of sampling in the short time interval of the same frame are also basically the same, so the difference between the two times of sampling voltages is calculated through a subsequent circuit; theoretically, the thermal noise of the pixel circuit can be completely eliminated.

A high matching low power dissipation low noise CDS circuit structure contains two sample switching transistors M2, M3, a array biasing transistor M1, two source connected transistors M4, M5, two capacitors C1, C2, a pair of array follow transistors M8, M9, a pair of source connected and grid connected array gate transistors M6, M7.

A mixer circuit is configured using a CMOS transistor (800), comprising a p-channel transistor (840A) and an n-channel transistor (840B) in which semiconductor substrates (810A, 810) with at least two crystal planes and a gate insulator (820A) formed on at least two of the crystal planes on the semiconductor substrate are comprised and the channel width of a channel formed in the semiconductor substrate along with the gate insulator is represented by summation of each of the channel widths of channels individually formed on said at least two crystal planes. Such a configuration allows reduction of 1/f noise, DC offset generated in output signals due to variation in electrical characteristics of a transistor element, and signal distortion based on the channel length modulation effect.

The invention relates to a front end circuit of accelerometer and a processing method of acceleration signal. The front end circuit is used to connect an acceleration sensor to obtain an original analog signal, and performing front end processing on the original analog signal. The front end circuit comprises: an amplifying circuit, which configured to be connected to the acceleration sensor to receive the original analog signal, and amplify the original analog signal; a low-pass filter circuit, which connected to the amplifying circuit for performing low-pass filtering processing on the amplified signal to eliminate noise. The amplifying circuit comprises: a first chopper circuit, which configured to be connected to the acceleration sensor to receive the original analog signal, and performa first chopping process on the original analog signal; an operational amplifier circuit, which connected to the first chopper circuit to amplify the output signal of the first chopper circuit; a second chopper circuit, which connected to the operational amplifier circuit to perform the second chopping process on the amplified signal. The noise in the front end circuit is small.