82results about "DC-isolation amplifier" patented technology

The signal detecting circuit has a first amplifier which amplifies the supplied signals and outputs the amplified signals from first and second output terminals; a switch unit which supplies the signals to the first amplifier such that the polarity thereof is reversed between the first and second periods; a first capacitor, one end of which is connected to the first output terminal; a second capacitor, one end of which is connected to the second output terminal; a first switch, one end of which is connected to the other end of the second capacitor; a second amplifier having an inverting input terminal connected to the other end of the first capacitor, a non-inverting input terminal connected to the other end of the first switch, and an output terminal; a second switch which is connected to between the output terminal and the inverting input terminal, a third switch, one end of which is connected to the other end of the second capacitor; a fourth switch, one end of which is connected to the other end of the non-inverting input terminal; a threshold voltage source which is connected to between the other end of the third switch and the other end of the fourth switch; and a reference voltage source which is connected to either one of the other end of the third switch and the other end of the fourth switch. In the first period, the first switch is off, and the second to fourth switches are on; in the second period, the first switch is on, and the second to fourth switches are off.

A switching amplifying method or a switching amplifier for obtaining one or more than one linearly amplified replicas of an input signal, is highly efficient, and does not have the disadvantage of “dead time” problem related to the class D amplifiers. Another aspect of the present invention provides a switching amplifier that is completely off when there is no input signal. Yet another aspect of the present invention provides a switching amplifier for obtaining a plurality of different linearly amplified replicas of the input signal, and adds more slave outputs easily and economically.

A semiconductor circuit comprising an input block having a first chopper providing a chopped voltage signal, a first transconductance converting said chopped voltage signal into a chopped current signal, a second chopper providing a demodulated current signal, a current integrator having an integrating capacitor providing a continuous-time signal, a first feedback path comprising: a sample-and-hold block and a first feedback block, the first feedback path providing a proportional feedback signal upstream of the current integrator. The amplification factor is at least 2. Charge stored on the integrating capacitor at the beginning of a sample period is linearly removed during one single sampling period. Each chopper operates at a chopping frequency. The sample-and-hold-block operates at a sampling frequency equal to an integer times the chopping frequency.

There is provided an operational amplifier which is operable as well when an operating voltage decreases without creating a range where a circuit would not operate or reducing circuit gain. High-pass filters 102-105 provide output signals therefrom to bias-set input nodes of differential amplifiers Gm1-Gm4 to a potential within a common-mode range in which the respective differential amplifiers Gm1-Gm4 are operable. In this manner, the respective differential amplifiers Gm1-Gm4 can be operated effectively regardless of the possible decrease in a supply voltage, enabling normal amplifying operation. In addition, reduction in gain due to the reduced operational voltage is avoided. Therefore, it is preferably applicable to the application where digital and analog circuits are loaded together on the same IC chip. When a high-pass filter is required at each input side of two- or more-stage differential amplifiers, a phase compensation method utilizing multiple paths is provided for a lower range of a phase margin created at the low frequency side, enabling normal amplitude operation.

A chopper stabilized amplifier with synchronous switched capacitor noise filtering is disclosed. In an exemplary embodiment, an apparatus includes a chopper amplifier having an input that receives an input signal and an output that outputs an amplified signal. The chopper amplifier includes an input chopping circuit and an output chopping circuit, where the input and output chopping circuits operate in response to a chop clock. The apparatus also includes a switched capacitor filter having an input that receives the amplified signal and an output that outputs a filtered signal. The switched capacitor filter operates in response to a filter clock. The apparatus also includes a filter timing adjuster that receives a reference voltage and adjusts a phase of the filter clock with respect to the chop clock to reduce chopper noise on that reference voltage.

The invention provides a high-performance digital self-calibration chopper precision amplifier which is low in cost and easy to implement and an implementation method. The amplifier mainly comprises a digital self-calibration loop and a chopper circuit. After the amplifier is energized, the amplifier is configured as a digital self-calibration state within a period of time, and the chopper circuit and an amplifier output circuit are switched off. The calibrated digital quantity is stored in a register, and input offset voltage of the amplifier is calibrated through a digital analog converter. After the digital self-calibration state is finished, a comparison output circuit is switched off, the amplifier is configured as a chopper magnifying state, and the chopper circuit and the amplifier output circuit work, so that the input offset voltage of the amplifier, temperature drift of the offset voltage and flicker noise are lowered.

Circuitry for providing improved pulse-type enhancement of the voltage supplied to a power amplifier (101) that is fed by a power supply that is connected to the power amplifier (101) at a feeding point through a main supply path that is connected via an inductor (L1). A second feeding point is used for enhancement by a capacitor that is discharged. A transformer L2, L3, M) is formed by mutually coupling an additional inductor (L3), through which an additional supply path is connected. Enhancement power is provided partially through the transformer L2, L3, M) and the remaining part thorough the capacitor (C1). This way, the total level of possible enhancement is increased, while minimizing distortion of the envelope of the amplified RF signal.

A capacitive gain amplifier circuit amplifies an input signal by a pair of differential amplifier circuits couples in series. The first differential amplifier circuit is reset during an autozero phase while disconnected from the second differential amplifier circuit, and the first and second differential amplifier circuits are connected together in series during a chop phase. A set of feedback capacitors is selectively switched in between respective outputs of the second differential amplifier circuit and respective inputs of the first differential amplifier circuit during the chop phase.

A chopper stabilized amplifier that utilizes a multi-frequency chopping signal to reduce chopping artifacts. By utilizing a multi-frequency chopping signal, the amplifier DC offset and flicker noise are translated to the higher chopping frequencies but are also smeared, or spread out in frequency and consequently lowered in amplitude. This lower amplitude signal allows for less stringent filtering requirements.

The method relates to a switched-capacitor bandgap reference circuit using chopping technique. A method includes providing a first voltage to a first output node during a first time interval, providing a second voltage to the first output node during a second time interval, and averaging the first and second voltages to provide a reference voltage to a second output node. The first voltage includes a proportional-to-absolute-temperature (PTAT) component, a complementary-to-absolute-temperature (CTAT) component, and a first residual offset component. The second voltage includes the PTAT component, the CTAT component, and a second residual offset component. An apparatus includes a discrete-time circuit to provide the first voltage to the first output node during the first time interval and to provide the second voltage to the first output node during the second time interval, and a filter to average the first and second voltages to provide the reference voltage to the second output node.

A power amplifier includes a first transformer, a first transistor, a first resistor, a second transformer, a second transistor, a second resistor, and a bias circuit. The first transformer drives the first transistor. The second transformer drives the second transistor. The first transformer is connected in series with the second transformer. The first transistor is connected in series with the second transistor. Therefore, the power amplifier has input impedance and output power both greater than those of a conventional power amplifier.

The application discloses an instrument amplifier comprising a capacitance feedback structure closed loop amplifier, an input capacitor charging module, a feedback capacitor discharge module, a noise separating module and a logic controller; the capacitance feedback structure closed loop amplifier comprises a full differential operational amplifier, a first input capacitor, a second input capacitor, a first feedback capacitor and a second feedback capacitor; the input capacitor charging module is used for periodically charging the first and second input capacitors; the feedback capacitor discharge module is used for periodically discharging the first and second feedback capacitors; the noise separating module is used for separating signals from noises through the chopper modulation technology; the logic controller is respectively connected with the input capacitor charging module, the feedback capacitor discharging module and the noise separating module so as to control each module to work, thus reducing instrument amplifier power consumption, and reducing instrument amplifier noises and cost.