90 results about "Negative feedback amplifier" patented technology

A distance image sensor for removing the background light and improving the charge transfer efficiency in a device for measuring the distance to an object by measuring the time-of-flight of the light.In a distance image sensor for determining the signals of two charge storage nodes which depend on the delay time of the modulated light, a signal by the background light is received from the third charge storage node or the two charge storage nodes in a period when the modulated light does not exist, and is subtracted from the signal which depends on the delay time of the two charge storage nodes, so as to remove the influence of the background. Also by using a buried diode as a photo-detector, and using an MOS gate as gate means, the charge transfer efficiency improves. The charge transfer efficiency is also improved by using a negative feedback amplifier where a capacitor is disposed between the input and output.

The variable gain amplifier includes a bias circuit (BC) 1, a matching circuit (MC) 2, a variable gain resistive feedback amplifier (FA) 3 and an output follower (EA) 4. The resistance values of the load resistance Rc and feedback resistance Rf are changed in cooperation. In a case of making the load resistance Rc a high resistance to set the low noise amplifier to a high gain, the feedback resistance Rf is also made a high resistance, the feedback time constant τfb(c1)≈2π·RfCbe / (1+gmRc) of the closed loop of the resistive negative feedback amplifier 3 becomes substantially constant, and then the amplifier has a gain small in frequency dependency over a wide bandwidth. In a case of making the load resistance Rc a low resistance to set the low noise amplifier to a low gain, the feedback resistance Rf is also made a low resistance. The feedback resistance Rf with the low resistance increases the negative feedback quantity, and thus the amplifier is set to a low gain. Also, the load resistance Rc is made a low resistance, and the feedback time constant τfb(c1) becomes substantially constant. The gain is not lowered further in a high frequency region.

A programmable gain amplifier with three stages uses fine steps, has a large gain range, and is monotonic. The first stage comprises several amplifiers, each including a resistive feedback loop. The feedback loop comprises a series of resistors, with each resistor acting as a tap. Since the number of resistors in the loop is unchanging, monotonicity and stability is guaranteed when resistance is increased using successive taps. A switch system connects two taps at a time to an interpolation stage. Each of these taps corresponds to a specific resistor level, and thus a gain level. The interpolation stage uses a plurality of current sources inside a feedback amplifier to control the interpolation, in order to provide fine gain steps.

A negative feedback amplifier has input portions for receiving input signals, adder circuits, a quadrature modulator for performing a quadrature modulation on outputs of the adder circuits, a first signal level variable control circuit for adjusting a level of an output signal from the quadrature modulator, an amplifier circuit for amplifying an output of the first signal level variable control circuit, a feedback circuit for negative feedbacking an output of the negative feedback circuit to the adder circuit, and a second control circuit for controlling an adjusting amount in the first signal level variable control circuit based on the output signal levels of the adder circuits so that the output signal levels of the adder circuits becomes predetermined values. The feedback circuit includes a first control circuit for controlling a signal level of the feedback circuit so that the output signal level of the amplifier circuit becomes a predetermined value.

An active resistor and its use in a negative feedback amplifier allow wide voltage swings on the input and output signals. One embodiment includes parallel pass-gate MOS transistors of opposite conductivity types connected between the input and output nodes. Bootstrapping transistors are connected between the gates of the pass-gate transistors and respective bias voltages. Coupling capacitors are connected between the gates and the output node. Additional coupling capacitors may be connected between the gates and the input node to make the resistor symmetric. In other embodiments, only one pass-gate transistor is used.

A preamplifier includes a negative-feedback amplifier circuit that converts a current signal from a photodetector into a voltage signal; and a conversion-gain control circuit that simultaneously controls a resistance value of a feedback resistor portion of the negative-feedback amplifier circuit and a resistance value of a load resistor portion of the negative-feedback amplifier circuit, based on the voltage signal from the negative-feedback amplifier circuit. Each of the feedback resistor portion and the load resistor portion includes a fixed resistor element, a MOSFET element, and a diode-connected transistor, connected in parallel.

In a double-loop negative feedback low noise amplifier having double negative feedback paths by a feedback transformer and a feedback resistor added to a cascode amplifier comprising transistors and a resistor, a phase compensation circuit comprising a capacitor and a resistor is added between the output terminal of the double-loop negative feedback low noise amplifier and the input terminal of the cascode amplifier, i.e., the input terminal of the input transistor, and a phase compensation circuit comprising a capacitor and a resistor is added to the upper-stage transistor of the cascode amplifier, i.e., the input terminal of the upper-stage transistor. Those phase compensation circuits enable a low noise negative feedback amplifier which maintains a high feedback loop gain to a high frequency band, has a wider bandwidth than a conventional one, and has a high dynamic range.

There is provided a feedback amplifier capable of easily controlling its dynamic range without a separate gain control signal generation circuit. The feedback amplifier includes an input terminal detecting an input voltage from input current, a feedback amplification unit amplifying the input voltage to generate an output signal, and an output terminal outputting a signal amplified by the feedback amplification unit. The feedback amplification unit includes a feedback circuit unit including a feedback resistor located between the input terminal and the output terminal, and a feedback transistor connected in parallel to the feedback resistor; and a bias circuit unit supplying a predetermined bias voltage to the feedback transistor of the feedback circuit unit and merged in the feedback amplification unit.

The invention relates to an open loop amplifier with stable output common-mode voltage. The open loop amplifier comprises a main amplifier unit and an auxiliary amplifier unit. Compared with a conventional negative feedback amplifier with stable output common-mode voltage, the open loop amplifier has the beneficial effects that the differential output common-mode voltage of the main amplifier unit under an open loop structure is stable; the differential output end of the main amplifier unit does not adopt a common-mode feedback circuit, so that the output load is lowered, the working conversion speed of the amplifier is increased, and the frequency of an analog input signal can exceed 1GHz when the dynamic indicator SFDR (Spurious Free Dynamic Range) of the main amplifier unit exceeds 70dB. The circuit provided by the invention is applied to the field of ultrahigh-speed sampling / retaining circuits in low-voltage CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process circuits with a high dynamic performance requirement.

A feedback architecture for ionizers that allows simultaneous adjustment of positive and negative ionizer power supplies. Balance and swing data are fed back to the ionizer through an intermediate module, which permits an extra level of signal processing. Swing information is returned to both power supplies in negative feedback mode. If swing is too high, both power supplies lower output. Balance is fed back in both negative and positive feedback mode. This architecture is compatible with multiple sensors and multiple ionizers.

The amplifier comprises an inverting negative feedback amplifier circuit using an operational amplifier, a comparator for comparing the potential of the negative phase input terminal of the operational amplifier with the reference potential Vref of the comparator, and a low-pass filter. The imaginary short state of the operational amplifier is lost when clipping occurs on the output signal. It is thus possible to detect clipping by monitoring the potential of the negative phase input terminal.

The invention provides a low-delay temperature compensation biasing circuit for time division duplexing mode, comprising: switch tube; potentiometer, one end connected with output end of the switch tube, voltage dividing output end passing through series-connected resistor and filter decoupling circuit and acting as output bias voltage, and another end earthed through temperature compensation diodes; the temperature compensation diodes comprise series-connected first and second diodes; the input voltage is inputted into a voltage stabilizing tube and then outputted to the switch tube, the earth end of the voltage stabilizing tube is connected in between the first and second diodes; a negative feedback amplifier is connected in series between the series-connected resistor and filter decoupling circuit. And it compensates bias voltage of the amplifier, makes the static current of the amplifier keep constant and electric performance not influenced.

The present invention provides a semiconductor integrated circuit device equipped with a negative feedback amplifier circuit or a step-down circuit which realizes stabilization of an output voltage effectively in response to a variation in power supply voltage. A constant current source is used to cause a bias current for setting current consumption to flow in a differential amplifying MOSFET. A capacitor is provided between an external power supply voltage and a predetermined circuit node to thereby detect a reduction in the external power supply voltage. An operating current of the differential amplifying MOSFET is increased through the use of a current flowing in the capacitor due to such an external power variation, thereby executing the operation of stabilizing an output voltage corresponding to the reduction in the external power supply voltage.

A feedback amplifier having an improved feedback network including two cross coupled switches that isolate the amplifier from extraneous undesired electrical signals present in a system or network when the amplifier is turned off (i.e., in an off-state). The cross coupled switches interconnect two feedback paths of a feedback network to enable out-of-phase differential signals to be summed and effectively canceled. Further, the feedback amplifier provides on-stage advantages to enable different amplifier characteristics and parameter to be selectively engaged by turning on or turning off certain feedback networks.