113results about How to "Reduce flicker noise" patented technology

A band-pass filter made up by an operational amplifier and by an input circuit. The input circuit is formed by a capacitive filtering element, connected to the input of the operational amplifier; a coupling switch, coupled between an input node and the capacitive filtering element; a capacitive sampling element, coupled between the input of the filter and the input node; and a sampling switch, coupled between the input node and a reference-potential line. The coupling switch and the input sampling switch close in phase opposition according to a succession of undesired components sampling and sensing steps, so that the capacitive sampling element forms a sampler for sampling the undesired component in the undesired components sampling step, in the absence of the component of interest, and forms a subtractor of the undesired components from the input signal in the sensing step.

A sigma-delta digital-to-analog converter comprises a current digital-to-analog converter (IDAC) stage which generates a current depending on an input digital signal. An output current-to-voltage converter converts the generated signal to a voltage on a continuous-time basis. The amplifier used in the output current-to-voltage converter is chopper-stabilized. The converter can be single bit or multi-bit. The IDAC stage can be implemented with a pair of branches, a first branch comprising a first biasing current source and a second branch comprising a second biasing current source. The biasing current sources can be chopper-stabilized by connecting the bias current sources to the output current-to-voltage converter by a set of switches. The switches connect the biasing current sources to the output current-to-voltage converter in a first configuration and a second, reversed, configuration. This modulates flicker noise contributed by the bias current sources to the chopping frequency. from where it can be removed by filtering downstream of the current-to-voltage converter.

Various systems and methods for implementing dynamic logic are disclosed herein. For example, some embodiments of the present invention provide LC tank circuits having an inductance and a capacitance. In addition, the circuits include a flicker noise reducing switch that is operable to selectively incorporate the capacitance such that an output of the circuit operates at a frequency based on a combination of the inductance and the capacitance.

The present invention relates amplifiers using metal oxide semiconductor based integrated circuits. The present invention is particularly but not exclusively related to audio application mixed signal chips. The present invention provides an analogue circuit for processing analogue signals in an integrated circuit comprising a number of metal oxide semiconductor transistor devices, the circuit stage comprising a first said transistor device having a first oxide thickness, and a second said transistor device having a second and different oxide thickness. Preferably a cascode based op amp structure is implemented.

The invention discloses a voltage-controlled oscillator with low power dissipation, low noise and high linear gain. The voltage-controlled oscillator comprises a first inductor, a second inductor, a distributed varactor structure circuit, a negative resistance differential pair circuit, a tail current tube circuit and an amplitude detection circuit, wherein the first inductor, the second inductor and the distributed varactor structure circuit are used to form an LC resonance network for generating an oscillating signal of the VCO with low power dissipation, low noise and high linear gain; the negative resistance differential pair circuit is connected with the LC resonance network and is used for providing energy compensation for the LC resonance network; the tail current tube circuit is connected with an output end of the voltage-controlled oscillator, and uses self-biasing to generate a direct current bias voltage to be used as supply voltage for providing direct current for the LC resonance network; the amplitude detection circuit is connected with an output end of the voltage-controlled oscillator for providing bias voltage for the negative resistance differential pair circuit and the tail current tube circuit. The voltage-controlled oscillator of the invention could realize low power dissipation, low noise and high linear gain.

An analog circuit for processing analog signals in an integrated circuit comprising a number of metal oxide semiconductor transistor devices. The circuit includes a first transistor device having a thin oxide thickness, and a second transistor device having a thicker oxide thickness. A voltage pulse protection is arranged to maintain the operating voltage of the thin oxide transistor in the presence of a rapidly rising voltage waveform (e.g. ESD), or at least to mitigate its effect on the thin oxide transistor device. Preferably a cascode based op amp structure is implemented.

A mixer circuit comprises an input stage arranged to convert an input voltage signal received at an input of the mixer circuit into at least one current signal, and a frequency conversion stage comprising at least one switching element arranged to convert a signal component of the at least one current signal from an input frequency to a output frequency. The input stage comprises at least one resistance connected between the input of the mixer circuit and the at least one switching element. The at least one switching element and the at least one resistance are arranged such that the at least one switching element comprises a ‘turn-on’ resistance that exhibits a resistivity that is a factor less than the at least one resistance connected thereto.

A mixer arrangement includes a mixer cell coupled by a signal input to a mixer input, and is embodied for frequency conversion of a signal present on the input side to an intermediate frequency. A first current source is coupled to the signal input of the mixer cell, and a second current source is coupled to a signal output of the mixer cell. The mixer arrangement furthermore includes a sensor circuit embodied for detection and for outputting of a value which is derived from a current of one of the current sources. A desired value regulating circuit is coupled by a feedback input to the sensor circuit and is designed for outputting a regulating signal to the one current source derived from a comparison of a signal present at a feedback input with a desired value.

A multi-bit sigma-delta analog-to-digital converter (ADC) has a single-ended input for receiving an analog input signal. A multi-bit feedback current digital-to-analog converter (IDAC) generates a multi-level feedback current depending on a multibit digital feedback signal from a Flash ADC. The feedback current is summed with the input signal with the feedback current. The summed signal is integrated on a continuous-time basis. The IDAC is selectively connectable to the summing node via a first path and a second path. The first path transmits current from the IDAC to the summing node with a first polarity and the second path transmits current from the IDAC to the summing node with an inverted polarity. This can reduce flicker noise and can allow the converter to operate without any mid-scale biasing current sources.

The invention provides an adjustable negative resistance structure-based multimode multi-channel mixer, which comprises a radio frequency input circuit, an adjustable negative resistance circuit, a digital control capacitor array circuit and a double-balanced differential structure circuit, wherein two input ports of the radio frequency input circuit are connected with radio frequency signals RF+ and RF-, and an output port of the radio frequency input circuit is directly connected with ports RFout+ and RFout-; the negative resistance size of the adjustable negative resistance circuit is controlled by two levels Vctrll and Vctrl, and an output end of the adjustable negative resistance circuit is connected with the RFout+ and the RFout-; an input port of the digital control capacitor array circuit is controlled by a digital signal, and two output ports of the digital control capacitor array circuit are connected with the RFout+ and the RFout-; and radio frequency current signals are input into the double-balanced differential structure circuit through the RFout+ and the RFout-, and are mixed with local oscillation signals LO+ and LO- to output intermediate-frequency signals IF+ and IF- to be then input into a rear-end module. By the adjustable negative resistance circuit, the equivalent parallel resistance of a capacitor array is eliminated, a noise coefficient is reduced, the gain of an active mixer is improved, the working frequency of the mixer can be controlled by a digital end, and the requirements of a broadband multi-channel system are met.

A quadrature VCO includes two cross-coupled differential pairs, two parallel LC tank circuits, two LO units and a plurality of source followers, supplying by a tail current source and a tail capacitor. The LC tank circuit constitutes of symmetrical spiral inductors and differential varactors, which constitutes of common anode diodes. The quadrature VCO circuitry is implemented on a chip with 2.4 GHz operating frequency. The quadrature VCO generates quadrature LO signals with high phase accuracy and good gain match under low power, good phase noise and small chip area, thus it can be applied to a variety of integrated transceivers.