227results about "Frequency-changer modifications" patented technology

An integrated circuit inductor includes a spiral pattern disposed upon a substrate. The track of the spiral is divided into multiple tracks to form a multi-track inductor. The individual tracks are disposed side by side and in different layers. Tracks that are aligned vertically are coupled by feed throughs, or vias. Multiple vias are used along the length of each of the multiple tracks. Tracks disposed in the same layer are joined together at their beginning, and at their termination. A patterned shield is fabricated from conductive fingers of n+ salicided material that is separated by non conducting polysilicon that fills the gaps between the fingers. The conductive fingers are coupled together in groups, which are in turn tied to a single point ground. In tying the groups together, a gap in the conducting path is provided to prevent ground loop currents. The shield is disposed between the multi-track inductor and the substrate.

A highly integrated terrestrial and cable tuner for receiving digital and analog television signals is disclosed. It achieves high performances in sensitivity, image rejection, dynamic range, channel selectivity and power consumption. A major-images rejection converter disclosed rejects third- and fifth-order images. Thus it significantly relaxes RF filter design in a tuner of a single-stage or a first-stage zero-IF/low-IF downconversion architecture. Different architectures and frequency planning are disclosed in accordance with specifications of TV standards to improve the overall performance of the tuner with a different or configurable IF output. The tuner is integrated by using standard processes, with minimal off-chip components excluding SAW and LC filters. Small tuner modules cost less than discrete (can) tuners. They can be used in digital/analog TV sets and portable and handheld TV devices and for mobile-phone TV reception.

A direct conversion tuner down-converts television signals, cable signals, or other signals directly from an RF frequency to an IF frequency and/or baseband, without an intermediate up-conversion step for image rejection. The direct conversion tuner includes a pre-select filter, an amplifier, an image reject mixer, and a poly-phase filter. The pre-select filter, amplifier, and the image reject mixer can be calibrated to provide sufficient image rejection to meet the NTSC requirements for TV signals. The entire direct conversion tuner can be fabricated on a single semiconductor substrate without requiring any off-chip components. The tuner configuration described herein is not limited to processing TV signals, and can be utilized to down-convert other RF signals to an IF frequency or baseband.

Image rejection calibration includes initializing the calibration mode by applying to quadrature mixers, in place of the wanted RF input, an RF source in the frequency range of the wanted RF input, sensing the power output from the poly-phase filter, developing gain adjust and phase adjust correction values in response to the power output and adjusting in accordance with the correction values the gain of the quadrature signals from the quadrature mixers to the poly-phase filter and the phase of local oscillator quadrature signals from the local oscillator to the quadrature mixers to reduce the power output.

A receiver (202) has a down-conversion receiver (304) for transforming a signal (201) from a first operating frequency to a second operating frequency that is lower than the first operating frequency, and a receiver filter (308) with chopper stabilization for filtering unwanted portions of the signal (306) at the second operating frequency and for generating a final filtered signal (203) at the second operating frequency.

An integrated VCO having an improved tuning range over process and temperature variations. There is therefore provided in a present embodiment of the invention an integrated VCO. The VCO comprises, a substrate, a VCO tuning control circuit responsive to a VCO state variable that is disposed upon the substrate, and a VCO disposed upon the substrate, having a tuning control voltage input falling within a VCO tuning range for adjusting a VCO frequency output, and having its tuning range adjusted by the tuning control circuit in response to the VCO state variable.

A downconverter and upconverter are provided which can obtain a sufficient image rejection ratio in a low-Intermediate Frequency (IF) scheme while reducing power consumption and can suppress Error Vector Magnitude (EVM)-related degradation in a zero-IF scheme. A complex-coefficient transversal filter rejects one side of a positive or negative frequency, and converts a Radio Frequency (RF) signal to a complex RF signal configured by real and imaginary parts. A local oscillator outputs a real local signal with a set frequency. A half-complex mixer, connected to the complex-coefficient transversal filter and the local oscillator, performs a frequency conversion process by multiplying the complex RF signal output from the complex-coefficient transversal filter and the real local signal output from the local oscillator, and outputs a complex signal of a frequency separated by the set frequency from a frequency of the RF signal.

An analogue single conversion tuner comprises a plurality of channels (1, 2, 3) for covering the whole of a desired reception bandwidth. Each tuner comprises an image reject mixer (18) connected to the tuner input (4) by a single tracking filter (16), for example of the single-tuned type.

The invention relates to an LC quadrature VCO (voltage controlled oscillator) which can reduce the intermittent noise, belonging to the technical field of integrated circuit, . The invention is characterized in that two negative resistance oscillators are connected together with a quadrature coupler to output quadrature signals; the reduced phase noise is implemented by using a more linear narrow-band turning variable capacitor structure, multiband switching digital array with a lower parasitic capacitance and an intermittent noise eliminating circuit reducing the intermittent noise getting into the LC oscillator when inputting voltage crossing the zero point.

An image rejection mixer includes an input terminal for receiving an input radio frequency (RF) signal, a mode selector coupled to the input terminal generating an output signal for either high side mixing or low side mixing, a first mixer coupled to receive the input RF signal and a signal from a local oscillator providing a signal having a local oscillator frequency, a phase converter coupled to convert the phase of the signal from the local oscillator, a second mixer coupled to receive the output signal from the mode selector and the phase-converted local oscillator signal, and a tunable polyphase filter coupled to receive output signals from the first mixer and the second mixer, the tunable polyphase filter providing an output signal having a variable intermediate frequency. In one embodiment, the variable intermediate frequency the tunable polyphase filter is implemented as a switchable intermediate frequency.

A wireless communications device, e.g., a mobile node supporting direct peer to peer communications, performs a self-calibration of one or more of: receiver IQ imbalance, transmitter IQ imbalance, receiver DC offset, and transmitter DC offset. The wireless communications device, operating in calibration mode, intentionally sets the oscillator frequency used for downconversion in its receiver module to a different frequency than the oscillator frequency used for upconversion in its transmitter module. A first baseband signal, e.g., a single tone test signal, is input to the transmitter module and an upconverted transmit signal is generated. The transmit signal is routed via a feedback loop to the receiver, which performs a downconversion operation. Power and/or phase measurements of the signals output from the downcoversion are used to determine IQ imbalance compensation information and DC offset compensation information. The determined compensation information is used subsequently when operating in a communications mode of operation.

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit. A receiver front end provides programable attenuation and a programable gain low noise amplifier. LC filters integrated onto the substrate in conjunction with image reject mixers provide image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. Active filters utilize multi track spiral inductors with shields to increase circuit Q. The filters incorporate a gain stage that provides improved dynamic range through the use of cross coupled auxiliary differential pair CMOS amplifiers to cancel distortion in a main linearized differential pair amplifier. Frequency planning provides additional image rejection. Local oscillator signal generation methods on chip reduce distortion. A PLL generates needed out of band LO signals. Direct synthesis generates in band LO signals. PLL VCOs are centered automatically. A differential crystal oscillator provides a frequency reference. Differential signal transmission throughout the receiver is used. ESD protection is provided by a pad ring and ESD clamping structure. Shunts utilize a gate boosting at each pin to discharge ESD build up. An IF VGA utilizes distortion cancellation achieved with cross coupled differential pair amplifiers having their V_ds dynamically modified in conjunction with current steering of the differential pairs sources.

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 image rejection mixer (IRM) for rejecting signals having image frequency and, more particularly, a mixer for rejecting signals of image frequency by using mismatch compensation is provided. The image rejection mixer comprises: first and second mixers; first and second converting means, each of which transforms each output of the first and second mixers to digital signal; third and fourth mixers, each of which mixes output of the first converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; fifth and sixth mixers, each of which mixes output of the second converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; means for subtracting; means for adding; and means for compensating gain-mismatch between the first and second mixers.