40results about How to "Reject common mode signals" patented technology

The invention discloses a sampling holding circuit applied to a high-speed high-precision circuit. The sampling holding circuit comprises a full-differential type operational amplifier, two sampling capacitors Cs, two sampling switches S1 and five selective switches and a low-pass filter circuit formed by a resistor R1 and a capacitor C1. The full-differential type operational amplifier is a gain enhancement folding cascade full-differential type operational amplifier, a sampling switch S1 is a grid voltage bootstrap switch, connected structures of the positive end and the negative end of the full-differential type operational amplifier are completely same, and a signal input end passes through the low-pass filter circuit to be connected with a lower pole plate of the sampling capacitors Cs through the sampling switches S1. A selective switch S3 is connected with the lower pole plate of the sampling capacitors Cs and the output end of the full-differential type operational amplifier. An upper pole plate of the sampling capacitors Cs is connected with the input end of the full-differential type operational amplifier, a selective switch S4 is connected with upper pole plates of the two sampling capacitors Cs, and a selective switch S2 is connected with the input end and the output end of the full-differential type operational amplifier. The sampling holding circuit can achieve sampling holding of the input signals in the high-speed high-precision circuit.

The invention discloses a single-converted-to-double low noise amplifier with a highly balanced and stabilized differential output gain phase. The amplifier comprises a common source or common emitter input amplifying transistor pair which comprises a first transistor and a fourth transistor, a common gate or common base amplifying transistor pair which comprises a second transistor and a third transistor, a tail current source pipe and output load circuits with tight coupling differential inductors; a fourth inductor L4 and a fifth inductor L5 are tight coupling differential inductors; C1 and C2 are differential capacitors with the same capacitance values; L0 and L1 also are tight coupling differential inductors. For the amplifier disclosed by the invention, since output loads adopt the tight coupling differential inductors L4 and L5 and the differential capacitors C1 and C2 for resonance, the balance and the stability of the differential output gain phase are improved, and the high-impedance tail current source pipe M5 can well restrain a common mode signal. The amplifier disclosed by the invention has excellent robustness when the PVT (Pressure Volume Temperature) and a working frequency point are changed, and at the same time, the amplifier has an excellent anti-interference capacity for the medium base noise.

A universal pulse width modulation method for a multi-level inverter includes the following steps: a, carrying out per unit of reference input voltages; b, calculating a two-level space vector pulse width modulation duty ratio; c, calculating in which layer a reference voltage vector is on; d, performing vector reverse mapping; e, inhibiting common-mode voltages; and f, generating pulse-width modulated waves. A voltage vector switching time duty ratio of an inverter is calculated by a simple two-level space voltage vector modulation algorithm, then vector compression is performed on the duty ratio, a mapping relation based on the voltage vector and level is established, and multi-level voltage conversion can be effectively achieved through the series of conversion. Through level conversion, the voltage vector that has a common-mode voltage inhibition capability can be output easily and quickly, and a specific pulse width modulation output state is selected to prevent generation of common-mode voltages, thereby effectively inhibiting common-mode components included in output voltages of a multi-level inverter.

The invention discloses a data through-the-earth transmission method based on sound waves, and belongs to the technical field of through-the-earth communication. The data through-the-earth transmission method is characterized in that low-frequency sine waves are taken as an information carrier, after data to be transmitted are processed such as being amplified and modulated through information transmitting equipment, sound wave signals are generated from sound generation equipment and are coupled to the earth, and then transmission of data is completed; after information is transmitted to a receiving end, a sound wave sensor senses the sound wave signals and the sound wave signals are converted into electric signals, the electric signals are processed such as being amplified, filtered and demodulated by information processing equipment at the receiving end, and information transmitted from a transmitting end is recovered. According to the method, due to adoption of a pulse width modulation and demodulation technique, the data transmission reliability is improved, and with the combination of hardware filtering and software filtering, a low bit error rate of information is ensured, the method can be effectively applied to ground-to-underground information issuing and rescue and relief work in hazard in underground working environments such as coal mines.

The present invention discloses one kind of single phase AC input electromagnetic interference inhibitor circuit, and relates to single phase input EMC circuit. The circuit consists of common-mode inductor including three windings and four capacitors connected together. The present invention can inhibit high frequency harmonic waves and reach corresponding EMC standard.

The invention discloses an open circuit stub loaded coupled line feed-based balance dual-passband filter. The balance dual-passband filter comprises a metal circuit; and the metal circuit comprises acoupled feed network and a resonator. By adopting an open circuit stub loaded type couple feed structure, common-mode signal suppression within a full-frequency range can be realized; and meanwhile, the adopted resonator has two controllable difference module resonant modes, so that dual-frequency difference module band-pass operation can be realized.

The invention provides a BFSK modulation circuit which comprises a first oscillating circuit, a second oscillating circuit and a comparison circuit. The first oscillating circuit and the second oscillating circuit are both connected with an input signal, the two circuits are in intermittent oscillation at the same time, and the input signal is converted into different voltage values; lastly, the frequency of the input signal is determined through a comparator, and namely the frequency of the input signal is '1' or '0'. By the adoption of the BFSK modulation circuit, a noise signal mixed with the input signal is a common-mode signal, the common-mode signal can be suppressed in a differential form, and therefore a comparison result is more accurate.

The invention relates to an electret microphone picking up differential signals. The electret microphone comprises a shell. The bottom of the shell is provided with sound holes. The top of the shell is provided with a circuit board. An electrode plate is arranged above the sound holes and in the shell. A second insulation gasket is arranged on the electrode plate. A vibration membrane is arranged on the second insulation gasket. A first insulation gasket is arranged on the vibration membrane. A back electrode plate is arranged on the first insulation gasket. The back electrode plate, the vibration membrane and the electrode plate are respectively and electrically connected with the circuit board. The back electrode plate and the vibration membrane form a capacitor. The vibration membrane and the electrode plate form another capacitor. The vibration membrane is connected with the ground. The back electrode plate is connected with an inverted input end of an operational amplifier. The electrode plate is connected with an in-phase input end of the operational amplifier. A differential structure is formed among the back electrode plate, the electrode plate and the vibration membrane, and therefore the electret microphone in differential structure is formed. The electret microphone can effectively amplify different-mode signals and restrain common-mode signals, thereby ensuring effects of a high signal to noise ratio and high sensitivity.

The invention discloses a single-channel earthquake signal acquisition device. The device comprises a signal input end, a first low pass filtering circuit, a front amplification circuit, an A/D conversion circuit, a controller and a wireless transmission circuit. The invention further discloses a earthquake signal acquisition system, the system comprises multiple geophones and multiple single-channel earthquake signal acquisition devices, wherein output ends of the multiple geophones are respectively connected with signal input ends of the single-channel earthquake signal acquisition devices. The device comprising the first low pass filtering circuit, the front amplification circuit, the A/D conversion circuit, the controller and the wireless transmission circuit is advantaged in that earthquake signal acquisition and wireless signal transmission can be realized. The system is advantaged in that the system is light, is easy to carry and is flexible for operation, earthquake signal acquisition operation efficiency is improved. The device and the system can be widely applied to earthquake signal acquisition fields.

The invention provides steam ablation equipment. The steam ablation equipment comprises a handle, a heating part, a power module, an injection part and a first processing circuit, wherein a containing cavity and a nozzle connected to the containing cavity are formed in the handle, the heating part is arranged in the containing cavity, the power module is electrically connected to the heating part to supply power to the heating part and enable the heating part to emit heat, and the injection part is connected to the containing cavity to inject water into the containing cavity. The first processing circuit comprises a first control module, a voltage comparison module, a temperature comparison module and a protection logic processing module, wherein the voltage comparison module and the temperature comparison module are both electrically connected to the first side of the protection logic processing module, and the first side of the protection logic processing module is electrically connected with the first control module.

The invention discloses an electroencephalogram amplifier which comprises a signal acquisition module, a current amplification module, a differential amplification module and a signal output module, the signal acquisition module comprises a recording electrode, a reference electrode and a ground electrode, and the current amplification module comprises a recording amplifier, a reference amplifier and a ground amplifier, the recording electrode is connected with the first resistor and serves as the front electrode of the recording amplifier, the rear electrode of the recording amplifier is connected with the front electrode of the differential amplification module, the reference electrode is connected with the second resistor and serves as the front electrode of the reference amplifier, the rear electrode of the reference amplifier is connected with the front electrode of the differential amplification module, and the rear electrode of the reference amplifier serves as the front electrode of the ground amplifier, the gain feedback end of the differential amplification module serves as the front electrode of the ground amplifier, and the ground electrode is connected with the third resistor and serves as the rear electrode of the ground amplifier, so that the electroencephalogram amplifier has the characteristic of high input impedance, and meanwhile, an output common-mode signal has an equipotential point and is zero, so that common-mode interference is eliminated, and a higher common-mode rejection ratio is achieved.