155results about "One-port active networks" patented technology

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programmable attenuation and a programmable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator. The VCOs in the PLLs are centered using a control circuit to center the tuning capacitance range. A differential crystal oscillator is advantageously used as a frequency reference. Differential signal transmission is advantageously used throughout the receiver.

The invention provides a method for testing the insulation resistance of a vehicle body, comprising the following steps: (1) generating a low-frequency AC signal and injecting the low-frequency AC signal into the vehicle body; (2) obtaining U through a first-level measurement circuit 9_30 ; 9‑30 The average value in one cycle reflects the unbalanced condition of the positive and negative poles to the body resistance; the variation dU in half a cycle 9_30 Participate in the calculation of the resistance value of the second-level measurement as the fluctuation parameter of the bus voltage; (3) obtain the AC voltage amplitude U through the second-level measurement circuit 9_25 , a single insulation resistance R = F (U 9_25 )*W, W is the weight, W=f(dU 9_30 ); (4) Take the average value of each measurement to obtain the vehicle body insulation resistance Ravr=(w1*R1+w2*R2+.....Wn*Rn) / (w1+w2+....Wn). On the basis of the original low-frequency signal injection method, the present invention correlates the weight of the weighted filter when calculating the insulation resistance with the variation of the DC bus voltage fluctuation, the weight is small when the bus voltage fluctuates greatly, and the weight is large when the bus voltage fluctuates small, thus Make the test results tend to be stable and reliable.

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator. The VCOs in the PLLs are centered using a control circuit to center the tuning capacitance range. A differential crystal oscillator is advantageously used as a frequency reference. Differential signal transmission is advantageously used throughout the receiver.

An interface circuit (INT C ) is disclosed, adapted to connect a microphone circuit (MC D ) to a preamplifier (P A ), the microphone circuit (MC D ) comprising a microphone (3) and at least an output node (M O , M O ') and the preamplifier (P A ) comprising at least an input node (10, 10') adapted to be connected to said output node (M O , M O ') through said interface circuit (INT C ). The interface circuit (INT C ) comprises at least a decoupling capacitor (C DEC ) for DC decoupling said input node (10, 10') from said output node (M O , M O '), the decoupling capacitor (C DEC ) having a first end connected / connectable to said input node (10, 10') and a second end connected / connectable to said output node (M O , M O '). The interface circuit (INT C ) comprises at least one active circuit (UG AMP , UG AMP ') connected to the first end of the decoupling capacitor (C DEC ), adapted to operatively act as a resistance multiplier and having an equivalent resistance that together with the decoupling capacitor (C DEC ) defines a high-pass filter operatively connected / connectable between the microphone (3) and the preamplifier (P A ) .

The invention discloses a signal compensation circuit for a water supply remote monitoring system. The circuit comprises a frequency selection input circuit, a feedback compensation circuit and an operational amplifier output circuit, wherein the frequency selection input circuit receives a signal in a signal input end for receiving a signal by a control terminal in the water supply remote monitoring system; the feedback compensation circuit uses an inductor L1 and a capacitor C7,the capacitor C8 forms a filter circuit for filtering; meanwhile, the triode Q1 and the triode Q3 are used for forming a switching circuit to filter out abnormal amplitude signals in the signals; a compensation signal is improved for the output end of the comparator AR3 after a power supply + 5V is subjected to voltage division by a resistor R8; wherein the operational amplifier AR2 and the triode Q2 form a feedback circuit to feed back a signal to the inverting input end of the comparator AR3; and finally, the operational amplifier output circuit uses an operational amplifier AR4 to perform in-phase amplification on the signal and then outputs the signal, so that automatic frequency modulation calibrationcan be performed on the signal received by the control terminal in the water supply remote monitoring system by using the signal in the signal input end, signal compensation is performed, and frequency hopping and attenuation phenomena of the signal are prevented.

The present invention discloses a high-precision weak signal tester and a high-precision weak signal test method which are suitable for the signal analysis and processing, and belong to the signal detection and processing field. A weak signal is a current signal of which the frequency is 30 Hz or less, and the amplitude Ipp is 10 pA or less. The high-precision weak signal tester disclosed by the present invention comprises a prepositive current-voltage conversion circuit module, a first-stage amplification circuit module, a voltage follower circuit module, a second-stage amplification and low-pass filtering circuit module, a signal reverse amplification circuit module and a protection circuit module. The present invention also discloses the high-precision weak signal test method based on the tester. The high-precision weak signal tester and the high-precision weak signal test method provided by the present invention are high in precision, low in noise and cost and simple in operation, can detect the ultra-low frequency weak signals with the high precision to record the signals and process the data, thereby improving the signal detection and processing precision.

An automatic time constant adjustment circuit has an error detection circuit and a variable time constant circuit. The error detection circuit detects, based on the resistance of an error reference resistor and the capacitance of an error reference capacitor provided therein, a resistance / capacitance error resulting from a variation attributable to an IC process, and then outputs a control signal corresponding to the resistance / capacitance error. The variable time constant circuit includes a resistance portion, a capacitance portion, and a switch portion. The resistance portion is build with one or more resistors. The capacitance portion is build with one or more capacitors. The switch portion sets the time constant of the variable time constant circuit according to the resistance / capacitance error by connecting together one of the resistors of the resistor portion and one of the capacitors of the capacitor portion according to the control signal.

A system and method for emulating an ideal diode for use in a power control device is provided. In one embodiment, the invention relates to a circuit for emulating an ideal diode, the circuit including at least one field effect transistor including a source, a drain, a gate, and a body diode, an input; an output coupled to the drain, a control circuit including a current sensor coupled between the input and the source, and a control circuit output coupled to the gate, wherein the control circuit is configured to activate the at least one field effect transistor based on whether the current flowing into the source is greater than a predetermined threshold, and wherein the body diode comprises an anode coupled to the source and a cathode coupled to the drain.

The embodiment of the invention discloses an active power filter, a duplexer, and wireless communication equipment. The active power filter comprises a first filter, a first amplifier, a second filter, a down converter, a third intermediate-frequency filter, a second amplifier, a fourth intermediate-frequency filter, an up converter, a fifth radio frequency filter, and a voltage-controlled oscillator which is used for providing local oscillation signals to the down converter and the up converter, wherein the input end of the first amplifier is connected with the output end of the first filter while the output end of the first amplifier is connected with the input end of the second filter; the output end of the second filter is connected with the input end of the third intermediate-frequency filter through the down converter; the output end of the third intermediate-frequency filter is connected with the input end of the second amplifier; the output end of the second amplifier is connected with the input end of the fourth intermediate-frequency filter; and the fourth intermediate-frequency filter is connected with the input end of the fifth radio frequency filter through the up converter. By virtue of the scheme, multiple excellent performance indexes of the filter can be taken into consideration conveniently.

The present invention provides an apparatus for enhancing Q factor of an inductor. The apparatus includes a negative resistance generator coupled to the inductor for providing a negative resistance, and a bias circuit coupled to the negative resistance generator for biasing the negative resistance generator.

The invention discloses a data signal distortion adjusting circuit. The circuit comprises a frequency acquisition circuit, a feedback calibration circuit and a voltage stabilization output circuit, wherein the frequency acquisition circuit acquires a low-frequency data signal received by a controller in the computer equipment; the feedback calibration circuit uses an operational amplifier AR1 anda capacitor C2 to form a noise reduction circuit, low frequency signal noise is filtered, one path of an output signal of the noise reduction circuit uses an operational amplifier AR2, a diode D2 anda diode D3 to form a detection circuit to filter a disturbance signal in the signal; in the second path, a triode Q4 and a triode Q5 form a push-pull circuit to prevent signal crossover distortion; and finally, the operational amplifier AR3 adds the two paths of signals and inputs the signals into the voltage stabilization output circuit. The voltage stabilization output circuit uses an operational amplifier AR4, an operational amplifier AR5, a capacitor C4 and a capacitor C5 to form a filter circuit to further stabilize signal potential output, and error correction can be carried out on low-frequency data signals received by a single-chip microcomputer port in a controller in computer equipment.

The invention discloses a chopped wave amplification conditioning chip system of human body biological weak and small signals. The system comprises a single-stage chopped wave core circuit, a samplingfilter circuit, a gain adjustable circuit and a low-pass filter circuit, which are connected in turn, the single-stage chopped wave core circuit is sued for performing chopped wave processing on effective biological small signals and a part of noise, so that the effective biological small signals is isolated from a frequency domain of the part of noise, the sampling filter circuit is used for eliminating a Burr voltage imported by a non-ideal switch and charge injection noise caused by opening and closing of the switch, the gain adjustable circuit is used for adjusting the gain direction of the chopped wave system in a digital manner, and the low-pass filter circuit is used for adjusting an effective broadband digit of the chopped wave system to filter the frequency of the part of noise.The chopped wave system disclosed by the invention can effectively identify and amplify the uV grade electroencephalogram EEG and mV grade electrocardiogram ECG signals.

The invention relates to a temperature adaptive ferrite switch driver. The ferrite switch driver comprises a single state trigger circuit, an RS trigger circuit, a pre-amplifying circuit, a voltage comparison circuit, a ferrite switch driving circuit and an operational amplifier circuit; the single state trigger circuit, the RS trigger circuit, the single state trigger circuit and the ferrite switch driving circuit are orderly connected; one end of the voltage comparison circuit is connected with the ferrite switch driving circuit, and the other end of the voltage comparison circuit is connected with the RS trigger circuit; and one end of the operational amplifier circuit is connected with the voltage comparison circuit, and the other end of the operational amplifier circuit is connected with the ferrite switch driving circuit. The temperature adaptive ferrite switch driver provided by the invention collects and calculates the ferrite material pulse current, and extracts temperature information of ferrite materials without using a temperature sensor, so as to perform related incentive compensation, thereby solving the problem of poorer compensation precision of a traditional temperature compensation method, and improving the wide temperature performance index of a ferrite switch.

The invention discloses an operation environment pre-warning device. The operation environment pre-warning device comprises a smoke signal acquisition circuit, a frequency division push-pull circuit and a filter output circuit, wherein the smoke signal acquisition circuit selects an LB-70C smoke signal acquisition device J1 to acquire smoke signals of factory operation environment; the frequency division push-pull circuit receives the smoke signals in two paths so as to acquire circuit output signals; in one path, an inductor L1, a resistor R7 and a capacitor C4 are utilized to form a composite circuit so as to filter high-frequency noise in the signals; in the other path, a triode Q1, a resistor R8 and a capacitor C2 are utilized to form a delay circuit so as to delay the signals, a triode Q6and a capacitor C3 are utilized to filter low-frequency noise in the signals, and a triode Q4, a triode Q5 and a capacitor C5 are utilized to form a switch circuit so as to detect the signals; andfinally, the filter output circuit utilizes a resistor R19, a resistor R20, a capacitor C6 and a capacitor C7 to form an RC circuit so as to carry out filter and output in sequence. According to theoperation environment pre-warning device, abnormal signals can be sent to a remote control terminal through a signal emitter E1 and an operation environment pre-warning module can be triggered to workand give an alarm.

Capacitance multiplier circuitry provides an increased equivalent capacitance, and may be implemented using a desirably small footprint. As may be implemented in accordance with one or more embodiments, a capacitor provides a first capacitance across first and second plates, and capacitance multiplier circuitry operates with the capacitor to provide a second equivalent capacitance that is a multiple of the first capacitance. The capacitance multiplier circuitry includes a first circuit path having a first resistor between the first plate and a common terminal, and a second circuit path having a switch and a second resistor between the second plate and the common terminal. An amplifier has differential inputs respectively corresponding to the first and second circuit paths and provides the second equivalent capacitance by controlling operation of the switch based upon the differential inputs and the respective resistances provided by the resistors in the first and second circuit paths.

The invention relates to a transistor resistance and a correlation method thereof. A transistor is operated in a resistance area, and the drain electrode of the transistor receives an input signal and the source electrode of the transistor outputs an output signal, and then a compensating circuit is used for generating a compensating signal which is sent into the grid electrode of the transistor according to the input signal, thus leading the voltage difference between the grid electrode and the source electrode of the transistor to approach a constant, so as to improve the resistance linearity of the transistor resistance.

The invention discloses an active low pass filter, which comprises an input matching module, a passive low pass filter module, an inter-stage matching module, a low noise amplifier module and an output matching module, wherein the output end of the input matching module is connected with the input end of the passive low pass filter module; the output end of the passive low pass filter module is connected with the input end of the inter-stage matching module; the output end of the inter-stage matching module is connected with the input end of the low noise amplifier module; the inter-stage matching module enables circuit impedance between the passive low pass filter module and the low noise amplifier module to achieve 50 ohm, and the low noise amplifier module enables the gain of the overall system to be 3 dB larger than the required; and the output end of the low noise amplifier module is connected with the input end of the output matching module. The overall structure comprises the three matching circuit modules, one passive low pass filter module and one low noise amplifier module, the structure is simple and practical, and the active low pass filter can be used in design of other types of filters.

A noise filter for an integrated circuit is proposed. The noise filter comprises a CMOS inverter and two capacitors. The input of the CMOS inverter is coupled with an input pad of the integrated circuit and the output of the CMOS inverter is coupled with an input buffer. The first capacitor is inserted between the output of the CMOS inverter and a first voltage source and the second capacitor is inserted between the output of the CMOS inverter and a second voltage source. A transfer gate may be in stead of the CMOS inverter.

The invention aims at solving the problem that according to an existing analog signal conditioning circuit, the employed devices are many, a circuit structure is complex, and the circuit design flexibility for the unipolarity / bipolarity difference of an A / D converter is relatively poor, and provides an optimized analog signal conditioning circuit and a working method thereof. The conditioning circuit comprises a filtering module composed of an active second-order low-pass filtering circuit; and an amplifier bias module composed of a bias circuit or a bias selection circuit and an amplifier circuit. An input end of the bias circuit is connected with an output end of the active second-order low-pass filtering circuit; the output end of the bias circuit is connected with the input end of the amplifier circuit; and the output end of the amplifier circuit outputs a conditioned analog signal. According to the circuit and the method, a circuit structure is optimized, the number of devices is reduced, the transmission distance is shortened, a fault rate is reduced, and the space and cost are reduced. Moreover, a working mode can be switched flexibly for the unipolarity / bipolarity of the A / D converter, the repeated design of the conditioning circuit is avoided, and the time cost is saved.

The invention discloses an improved voltage controlled memristor simulator comprising two operational amplifiers Ua and Ub, two multipliers M1 and M2, a capacitor C0 and three resistors Ra, Rb and Rc. The first operational amplifier Ua forms a voltage following circuit and is used for avoiding the load effect. The second operational amplifier Ub is connected with the resistor Ra and the capacitor C0 to form an integrator circuit so as to realize integral operation, and the resistor Rb is used for avoiding DC voltage drift of the integrator. The multipliers are used for multiplication operation of voltage signals and finally form voltage difference at the two ends of the resistor Rc. The current flowing through the resistor Rc is current flowing through the memristor simulator. The improved voltage controlled memristor simulator has no current inverter and no DC voltage drift and is simple in structure and simple in experimental observation and can be used as a new memristor simulator to be applied to different chaotic circuits to generate chaotic signals.

The invention discloses a big data signal transmission anti-interference circuit comprising a high frequency component increasing circuit, a feedback anti-interference circuit and a stable output circuit, wherein the high frequency component increasing circuit receives a signal in a big data signal transmission channel, the feedback anti-interference circuit adopts an inductor L3 and an inductor L4 for filtering, meanwhile, an inductor L5, an inductor L6, a capacitor C6, a diode D2 and a capacitor C7 are designed to form a Z-type anti-interference circuit, a signal output by the Z-type anti-interference circuit is fed back by an operational amplifier AR1 to serve as a control signal to adjust the high frequency component increasing circuit, the stable output circuit receives the signal output by the feedback anti-interference circuit, a triode Q3, a triode Q4 and a voltage stabilizing diode ZD1 are used for constituting a voltage stabilizing circuit to stabilize the voltage, meanwhile,a slide rheostat RW2 is designed to adjust the voltage stabilizing value of the voltage stabilizing circuit, and finally the voltage stabilizing value is input into a control terminal of big data signals, thereby effectively improving the anti-interference property of the big data signals and stabilizing the signals.

A frequency synthesizer for a miniaturized ODU receiving channel comprises a phase detector, a loop filter and a voltage controlled oscillator, wherein the phase detector, the loop filter and the voltage controlled oscillator are serially connected. The first reference source input end of the phase detector is electrically connected to an external reference source. The NC interface of the phase detector is electrically connected with a single chip microcomputer, The output end of the phase detector is electrically connected to the input end of the loop filter, the output end of the loop filteris electrically connected to the voltage control end of the voltage controlled oscillator, the output end of the oscillation signal of the voltage controlled oscillator outputs a composite signal, and the output end of the oscillation signal is also electrically connected to the second reference source input end of the phase detector. The composition of the chip and the interface network used inthe circuit is further disclosed. The frequency synthesizer is applied to the satellite communication receiving channel, which can change the required synthesized signal frequency by parameter configuration, and has the characteristics of stability and reliability. It also has the advantages of saving power, reducing volume and cost.

Provided is a configuration capable of improving an attenuation characteristic of an RF signal outside a frequency band of a transmitting signal inputted to a transmitting terminal, and improving an isolation characteristic between a transmitting filter and a receiving filter without increasing the size of a radio frequency module. A propagation path WP for further improving a filter characteristic without deteriorating an attenuation characteristic outside a pass band of a transmitting filter 14 can be formed by a simple configuration, and consequently an attenuation characteristic of an RF signal outside a frequency band of a transmitting signal can be improved without increasing the size of a radio frequency module 1. Further, an RF signal outside the frequency band of the transmitting signal and within approximately the same frequency band as a received signal is prevented from going around from a signal path on the output terminal 14b side of the transmitting filter 14 to the receiving filter 15 side and being outputted from a receiving terminal Rxa, and consequently an isolation characteristic between the transmitting filter 14 and the receiving filter 15 can be improved.

The invention discloses a memristor-based all-pass filter circuit. A diode Wien bridge circuit of a first-order generalized memristor is characterized by comprising a diode IN4148, a capacitor and a resistor, wherein the diode IN4148 achieves the Wien bridge function; and the capacitor and the resistor form an RC oscillation circuit. According to the memristor-based all-pass filter circuit, filter circuits, such as a first-order low-pass filter, a second-order low-pass filter, a high-pass filter, a band-pass filter and an all-pass filter, in an analogue circuit are achieved on the basis of the diode Wien bridge circuit of the first-order generalized memristor; and simple method and circuit are provided for research on the first-order generalized memristor formed by a diode Wien bridge.

A circuit arrangement for generating an electronically controlled electrical resistance by apparatus of at least one MOS transistor. A source-drain junction of the MOS transistor is used for the generation of the electrical resistance between a first and a second terminal, in order to optimize the linearity of the electrical resistance, there have been provided means for generating a bulk signal, which apparatus generate from the voltage on that terminal of the circuit arrangement which is coupled to the source electrode of an associated MOS transistor a signal for driving a bulk electrode of the associated MOS transistor, which signal is generated from the voltage on the terminal and an additionally superposed direct voltage of such a polarity that, depending on the doping type of the MOS transistor the formation of a diode between the source and bulk regions of this MOS transistor is avoided.

The present invention provides an apparatus for enhancing Q factor of an inductor. The apparatus includes a negative resistance generator coupled to the inductor for providing a negative resistance, and a bias circuit coupled to the negative resistance generator for biasing the negative resistance generator.