24 results about "Operational amplifier" patented technology

The invention discloses a current generating circuit with an adjustable temperature coefficient. The current generating circuit comprises a current mirror, an operational amplifier, a switching tube,at least two positive temperature coefficient resistors, at least two negative temperature coefficient resistors, a positive temperature coefficient switch and a negative temperature coefficient switch. Thus, on the basis of a voltage-to-current circuit in the prior art, output current is appropriately matched, the current generating circuit achieves the adjustable temperature coefficient, resistance matching is different from traditional pure serial connection or pure parallel connection, and circuit space is saved; the accuracy of the temperature coefficient is high.

The invention relates to the technology of a power source and an integrated circuit, in particular to a DC-DC converter with the output voltages capable of being adjusted quickly. The DC-DC converter comprises a driving circuit, a PMOS tube MP, an NMOS tube MN, a PWM comparator, an EA amplifier, an inductor L, a capacitor C, a resistor R and a power source Vin. The DC-DC converter is characterized in that a calculating amplifier is further included, the driving circuit, the PMOS tube MP, the NMOS tube MN, the PWM comparator, the EA amplifier, the inductor L, the capacitor C, the resistor R and the power source Vin form a traditional DC-DC converter, and the positive input end and the output end of the calculating amplifier are connected to be used as one end, connected to the capacitor C, of a bumper. The DC-DC converter has the advantages of being simple in structure, easy to achieve, low in power consumption, and capable of achieving quick adjusting of the output voltages of the DC-DC converter only by small domain area. The DC-DC converter is particularly suitable for DC-DC converters.

The invention discloses a circuit for a low-voltage adjustable band-gap reference source. Collectors and bases of three PNP triodes are grounded; the emitter of the first PNP triode is connected with one end of a first resistor; the other end of the first resistor is connected with the positive input end of an operational amplifier and the drain of a first P-channel metal oxide semiconductor (PMOS) transistor; the emitter of the second PNP triode is connected with the negative input end of the operational amplifier and the drain of a second PMOS transistor; the emitter of the third PNP triode is connected with one end of a second resistor; the other end of the second resistor is connected with the drain of a third PMOS transistor and one end of a third resistor; the other end of the third resistor is grounded; the output end of the operational amplifier is connected with the grids of the three PMOS transistors; and the sources of the three PMOS transistors are connected with a power supply. According to the circuit, configurable reference output voltage can be realized; and the influence of offset voltage of the operational amplifier on a starting circuit is avoided.

The invention discloses a low-power consumption bandwidth multiplication chopping stabilized operational amplifier based on an MOS (metal oxide semiconductor) device, which belongs to the field of design of analog integrated circuits. The low-power consumption bandwidth multiplication chopping stabilized operational amplifier comprises two frequency mixers, a shunt input stage, an intermediate stage for amplifying recovered current and a rail-to-rail output stage, wherein one frequency mixer is placed in front of an amplifier input stage, and the other frequency mixer is placed behind an amplifier output stage, thereby realizing the functions of raising frequency and reducing frequency of input signals; the shunt input stage is used for converting input voltage signals to current signals and forming small signal current in forward and backward directions; the intermediate stage for amplifying the recovered current comprises four low-voltage current mirrors and can realize the amplification of the recovered current; and the rail-to-rail output stage is used for realizing the rail-to-rail output of the signals. The low-power consumption bandwidth multiplication chopping stabilized operational amplifier has the capacity of improving bandwidth by nearly three times under the situation of not obviously increasing power consumption, and can reduce low-frequency 1/f noise, increase low-frequency gain, and reduce power consumption above one half while keeping the same bandwidth, the noise and other performances, thereby further improving the performances of the circuit.

An output circuit comprises first and second transistors, a driving circuit and a current mirror circuit. The driving circuit supplies a relatively small constant current to the base of the first transistor. When a current flows to the collector of the first transistor, a current with a magnitude set at a fixed ratio with respect to the current flows to the collector of the second transistor, and a current proportional to the current flowing to the collector of the second transistor flows to the base of the first transistor by way of the current mirror circuit. That is, a current, which is determined in accordance with a current flowing to the collector of the first transistor, flows to the base of the first transistor.

A sensor device is provided with a voltage detection type sensor unit for converting a physical quantity into a voltage value and outputting a voltage signal indicating the voltage value; a chopper amplifier unit for generating a modulation signal by chopping the voltage signal output from the sensor unit with a predetermined chopping frequency, amplifying the modulation signal into an amplification signal, then demodulating the amplification signal and outputting it as an output signal; an integration unit including an operational amplifier, an input resistor connected to the inverting input terminal of the operational amplifier and a capacitor connected between the inverting input terminal and an output terminal of the operational amplifier; and a digital conversion unit for converting the output signal integrated by the integration unit into a digital signal.

A bandgap reference voltage circuit comprises a current mirror unit, an operation amplifier (OP), a first resistor, a second resistor, an auxiliary unit, and a voltage generation circuit. An output end of the OP is coupled to a feedback end of the current mirror unit. An end of the first resistor and an end of the second resistor are coupled to a positive input end of the OP. Another end of the first resistor is coupled to a second end of the current mirror unit. A second end of the voltage generation circuit is coupled to another end of the second resistor. An end of the auxiliary unit is coupled to a negative input end of the OP and a first end of the voltage generation circuit, and another end of the auxiliary unit is coupled to the first end of the current mirror unit.

The invention particularly relates to a memristor-based automatic gain control circuit. The technical scheme is as follows: the circuit consists of a variable gain amplification module (1), a comparator (4) and a peak value detection module (5); the variable gain amplification module (1) consists of an operational amplifier circuit (2) and a memristor (3); a terminal M2 of the memristor (3) is connected with an input end Rc of the operational amplifier circuit (2); an input end Vi of the operational amplifier circuit (2) is externally connected with an input signal Vin; an output end VVGA of the operational amplifier circuit (2) is respectively connected with an input end VVGAP of the peak value detection module (5) and the input end Vw of a peripheral circuit; a terminal M1 of the memristor (3) is connected with an output end Vc of the comparator (4); an input end ViVGAP of the comparator (4) is connected with an output end ViVGA of the peak value detection module (5); and an input end VREF1 of the comparator (4) is externally connected with a reference electric level VREF. The memristor based automatic gain control circuit provided by the invention has the advantages of simple structure, low cost and high accuracy.

The invention discloses a detection circuit capable of detecting a plurality of arbitrary-combination keys by low cost, and a processing method. The detection circuit comprises control chips and a matrix key circuit, wherein the control chips include a single chip microcomputer, an MCU (Microprogrammed Control Unit), a CPLD (Complex Programmable Logic Device), an FPGA (Field Programmable Gate Array), an ARM (Advanced RISC Machine) and the like; each control chip is provided with R+C pieces of IO (Input/Output) pins; an R wire controls the IO as input and has an external interruption function;in addition, each IO pin has IO function settings, including floating, open-drain, push-pull, upward pull, downward pull and the like; and an AD (Analogue/ Digital) sampling functional or operationalamplifier, a comparator or a plug-in operational amplifier and a comparator are built in the controller chip. The detection circuit has the beneficial effects that no diodes are required, or only a small quantity of diodes is required to realize low-cost any-key no conflict and full-key no conflict, an audion MOS (Metal Oxide Semiconductor) tube and the like can be cooperated to realize IO reuse for LED (Light Emitting Diode) light control.

A C/V integrated capacitive humidity sensor interface circuit is suitable for the field of Internet of Things. Humidity sensor interface circuit is composed of folded cascode operational amplifier, reference current source, bias circuit and compensation circuit. The first stage adopts a folded cascode structure, which provides higher gain; the second stage adopts a common source structure, which provides a higher output swing. The bias circuit adopts a self-starting bootstrap reference current source, thereby reducing the influence of the power supply voltage on the charging and discharging of the capacitor. The circuit has high sensitivity, fast dynamic response, good stability, simple structure, easy digitization, and good anti-interference and reliability.

A driver utilizes selective biasing of the terminal of an operational amplifier to reduce offset in the operational amplifier output. Each operational amplifier input includes a differential input pair of transistors including a NMOS transistor and PMOS transistor. At low and high ends of the input voltage range these transistors are selectively and individually coupled to either a standard input or biased to be on so as to contribute offset for offset compensation. The transistors are biased in a conventional manner for input voltages between the low and high ends of the voltage range.

The invention discloses an integratable power supply filtering circuit, which comprises a rectification circuit, N levels of pulsating direct current electric charge shifting and voltage merging rectification circuits and N levels of electronic filtering circuits, wherein the rectification circuit consists of a bridge type rectifier DW1; the N levels of pulsating direct current electric charge shifting and voltage merging rectification circuits comprise at least N levels of pulsating direct current electric charge shifting unit circuits and at least N+1 levels of voltage merging rectificationunit circuits; each level of pulsating direct current electric charge shifting unit circuit consists of a resistor, a capacitor and a transistor; each level of voltage merging rectification unit circuit consists of a diode and a transistor; and the N levels of electronic filtering circuits comprise at least one unit electronic filtering circuit, wherein each unit electronic filtering circuit consists of two audions, seven resistors, one capacitor and an operational amplifier.

The invention discloses an intermediate frequency direct current detuning calibration DCOC circuit applied to a radio frequency signal receiver, the intermediate frequency direct current detuning calibration DCOC circuit comprises an operational amplifier OPA1, an NMOS transistor M1, an NMOS transistor M2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2, one output end of the operational amplifier OPA1 is connected with the resistor R2, and two ends of the capacitor C1 are respectively connected with the output end and an in-phase input end of the operational amplifier OPA1. The other output end of the operational amplifier OPA1 is connected with the resistor R4, and the two ends of the capacitor C2 are connected with the output end of the operational amplifier OPA1 and the inverted input end of the operational amplifier OPA1 respectively. The source electrode of the NMOS transistor M1 is connected with the in-phase input end of the operational amplifier OPA1, and the drain electrode of the NMOS transistor M1 is connected with one end of the resistor R1. The source electrode of the NMOS transistor M2 is connected with the inverted input end of the operational amplifier OPA1, and the drain electrode of the NMOS transistor M2 is connected with one end of the resistor R3. According to the invention, low direct-current offset calibration high-pass turning frequency and small layout area can be realized, the overall area of a chip is reduced, and the manufacturing cost is reduced.

The invention discloses a high-load stepless dimming control device and a dimming system for application thereof. The device comprises a microprocessor, a microprocessor connected with a power supplymodule, and the microprocessor is connected with a load driving circuit through an operational amplifier, and the operational amplifier is also connected with a power supply module. A load drive circuit is use for accessing that light device; The load driving circuit is connected with the voltage monitoring module and the temperature monitoring module respectively, and the voltage monitoring module and the temperature monitoring module are connected with the microprocessor. The microprocessor includes an external communication interface. The operational amplifier comprises a filter module; Byproviding a load driving circuit with a high load in the device, the load driving circuit can support the load driving of a plurality of lighting devices, so that only one dimming control device can be used for the plurality of lighting devices to complete the dimming, and the installation and the tracing are simple and the input cost is low.

The invention discloses a self-adaptive turn-off time generation circuit and a buck converter, the self-adaptive turn-off time generation circuit comprises a current generation circuit unit, the current generation circuit unit comprises a first current generation circuit and a second current generation circuit, the first current generation circuit is used for generating a first current IC of a proportional input power supply, and the second current generation circuit is used for generating a second current IC of a proportional input power supply; the second current generating circuit is used for generating a second current IB of a proportional input-output power supply difference; and the self-adaptive turn-off time generating unit is used for generating self-adaptive turn-off time according to the first current IC and the second current IB. According to the invention, the self-adaptive turn-off time can be generated, and the time is only related to the size (RC) of a passive device in the circuit and the output/input power supply voltage ratio (VO/VI); the first current generation circuit avoids the use of an operational amplifier, so that the design difficulty of the circuit is reduced, and the current consumption is reduced; the second current generating circuit perfectly solves the problem that the output minimum voltage is limited, so that the output voltage can work from 0V to the input voltage all the time.

The invention relates to a single-ended electrical signal measuring instrument relating to electrical signal measurement. The single-ended electrical signal measuring instrument comprises an operational amplifier, a divider resistor, a feedback resistor, a voltage generation resistor, a battery and a shielding box, wherein both ends of the voltage generation resistor are respectively connected with a reference zero and the positive-phase input end of the operational amplifier; both ends of the divider resistor are respectively connected with the reference zero and the reverse-phase end of the operational amplifier; both ends of the feedback resistor are respectively connected with the output end and the reverse-phase end of the operational amplifier; the battery is connected between the power supply end of the operational amplifier and the reference zero; a circuit is placed into the shielding box; and the positive-phase input end and the output end of the operational amplifier are respectively the input end and the output end of the single-ended electrical signal measuring instrument. The noise of a ground wire is measured by adopting a single-ended method, and the invention can directly measure the potential float of an appointed ground wire without an assistant ground wire, thereby making up the limitation that the traditional double-ended measurement can not show which ground wire generates the noise.

The invention discloses a communication method between active imbalance compensators. The method comprises the following steps that: 1, an active unbalance compensator (AUC) sends out a signal instruction, the instruction is modulated by a PWM modulator in the compensator before being sent out, and on the premise of ensuring the original power function, the switching between two carriers with different frequencies is utilized, therefore, corresponding ripples are generated in the circuit; 2, the communication receiving ends of other AUCs amplify the signals through an operational amplifier circuit; 3, a characteristic signal is filtered by a band-pass filter in a communication receiving circuit; and 4, the communication receiving circuit reads and analyzes the signal. According to the invention, the problem that AUCs cannot communicate with each other is solved, so that the capacities of the AUCs installed on different branches on a power line can be utilized to the maximum extent, andthe overall three-phase imbalance degree of the line is reduced.

The invention discloses a novel follow current protection circuit suitable for a direct current motor, which is used for protecting an H-bridge driving power supply VM, so that the potential of the H-bridge driving power supply VM is not increased by current released on an inductor during fast follow current of the motor, and the situation that a large-area bypass capacitor needs to be connected to the driving power supply VM when an H bridge is used as a driving circuit is avoided. The circuit comprises an H-bridge driving circuit, an operational amplifier (OP), an anti-straight-through protection circuit, an operational amplifier reference generation circuit, a digital logic control circuit and a motor (DCM). The H-bridge driving circuit drives the motor to operate and generates corresponding voltages OUT1 and OUT2 at the two ends of the motor; the positive end of the operational amplifier samples the voltage of the OUT1 or the OUT2, the negative end of the operational amplifier samples the reference voltage VREF, the output of the operational amplifier controls the grid end of the low-side power tube through processing of the digital logic control circuit, then the output voltage of the H bridge is controlled, and a negative feedback loop is formed.

The invention discloses a switching power supply control system of multiple voltage levels, and relates to electronic technology. The system comprises a first level voltage adjusting module, a second level voltage adjusting module, a low-voltage control module and a high-voltage control module, wherein the first level voltage adjusting module comprises a feedback circuit consisting of a depletionmetal oxide semiconductor field effect transistor (MOSFET) device and an operational amplifier, and the source of the depletion MOSFET device is the output end of the first level voltage adjusting module; and a level conversion circuit is connected in series between the low-voltage control module and the high-voltage control module, and the level conversion circuit is also connected with the output end of the first level voltage adjusting module and the output end of the second level voltage adjusting module. The system can provide higher driving voltage at the same time of ensuring the control precision and broaden the model selection range of an external power device.