164 results about "Quadrature mixer" patented technology

A feedback image rejection downconversion system is described, which can be used in low IF receivers with good performance and completely integrated. In the forward path of the system, quadrature mixers and complex filters are used for frequency downconversion and separation of the RF signal from the image signal. In the feedback path, a correlator, a gain mismatch estimator and two VGAs have been used to detect, estimate and compensate the amplitude and phase mismatch between the forward I and Q path signals. The whole system is self-tuned and can operate in both closed and open loop mode. A very high and robust image rejection ratio (over 60 dB) has been achieved.

A wireless receiver for multiple frequency bands reception includes a single receive radio frequency (RF) circuit (160, 170) having an RF bandpass substantially confined to encompass at least two non-overlapped such frequency bands at RF, a single in-phase and quadrature (approximately I, Q) pair of intermediate frequency (IF) sections (120I, 120Q) having an IF passband, and a mixer circuit (110) including an in-phase and quadrature (I,Q) pair of mixers (110I, 110Q) fed by said RF circuit (160, 170) and having a local oscillator (100) with in-phase and quadrature outputs coupled to said mixers (110I, 110Q) respectively, said mixer circuit (110) operable to inject and substantially overlap the at least two non-overlapped frequency bands with each other into the IQ IF sections (120I, 120Q) in the IF passband, the IF passband substantially confined to a bandwidth encompassing the thereby-overlapped frequency bands. Other receivers, circuits.

A quadrature mixer with an LO input is provided. The quadrature mixer receives a signal having a frequency F_LO and a signal input having a frequency F_SIG, and has an output that comprises an output impedance that is high at frequencies of |F_LO−F_SIG | and |F_LO+F_SIG| and low at other. A mixer coupled to the output impedance interacts with the output impedance such that an impedance presented at the signal input is high for signals at F_SIG if F_SIG is a predetermined signal frequency, and low at other frequencies.

A high performance radio frequency receiver includes a low noise amplifier with large binary and stepped gain control range, controlled impedance, and enhanced blocker immunity, for amplifying and converting a radio frequency signal to a current; a pulse generator for generating in-phase and quadrature pulses; a crossover correction circuit and pulse shaper for controlling a crossover threshold of the pulses and interaction between in-phase and quadrature mixers; and a double balanced mixer for combining the RF signal with the pulses to generate an intermediate frequency or baseband zero intermediate frequency current-mode signal. The in-phase and quadrature pulses have a duty cycle of 20-35%. The intermediate frequency signal and second order harmonics may be filtered with a high frequency low pass filter and a current injected complex direct-coupled filter. Decreased die size, current drain, cost, and complexity, as well as improvements in gain, 1/f noise, noise figure, sensitivity, and linearity may result.

A receiver circuit includes an oscillator circuit configured to generate a calibration tone and a phase locked loop (PLL) reference signal. An output frequency of the VCO may be divided by respective amounts to derive a desired calibration tone frequency and a desired PLL reference signal frequency. In addition to the oscillator circuit, the receiver circuit may further include a phase locked circuit configured to generate a PLL output signal that is phase locked in relation to the PLL reference signal. During a calibration mode, a quadrature generator may be used to generate quadrature mixer local oscillator signals dependent upon the PLL output signal, and an in-phase/quadrature mixer may be used to mix the calibration tone with the quadrature mixer LO signals.

The invention discloses a digital processing method of an altimeter of a linear frequency modulation continuous wave radar, which belongs to the field of the radio altimeters. The digital processing method comprises the following steps: step 1, obtaining beating signals from an orthogonal mixer arranged at the front end of the altimeter of the radar, and carrying out A/D (analog-to-digital) sampling to obtain a digital signal sequence; step 2, performing Fourier transform on the digital signal sequence, and calculating the amplitude of a spectral line; step 3, judging according to the amplitude of the spectral line of an amplitude spectrum, and measuring the beating frequency of the digital signal sequence; step 4, refining the frequency spectrum, calculating the slope correction of saw-tooth wave, and correcting the slope of the voltage signals of the saw-tooth wave; and step 5, calculating the high value of the current altimeter according to the slope of the voltage signals of the saw-tooth wave. The FFT-CZT method adopted by the invention is insensitive to noises and can perfectly work at lower signal-to-noise ratio, but the measurement precision is reduced. Because of having no limit on the properties of the targets, the digital processing method can be applied to the measurement and the analysis of point targets or surface targets.

A quadrature demodulator 408′ and a quadrature modulator 908′ convert a reception intermediate frequency signal 151 into reception baseband signals 157 and 158, and also convert transmission baseband signals 657 and 658 into a transmission intermediate frequency signal 651, respectively. While local oscillation signals having frequencies suitable for the respective bands are outputted from a commonly used local oscillator 111, such a local oscillation signal obtained by shifting a phase thereof π/2 by a phase shifter 412 is supplied to one mixer of quadrature mixers 109 and 609, and such a signal obtained by inverting, or not inverting the plurality of the local oscillation signal by an exclusive OR gate circuit 413 in response to a band switching signal 153 is supplied to the other mixer of quadrature mixers 110 and 610.

The invention discloses a digital signal down-conversion processing system based on an MIMO real-time testing platform, pertaining to the technical field of digital signal processing. The system comprises four DDC modules and each DDC module consists of four independent digital signal down-conversion processing channels. Each channel consists of an analog-to-digital converter, a digital quarter mixer and a digital decimation filter set. The digital quarter mixer consists of a digital controlled oscillator and two paths of multipliers, and the digital controlled oscillator is respectively connected with the two multipliers; the digital decimation filter set consists of two groups of filters with complete same parameters and each filter group respectively comprises a CIC decimation filter, a CFIR compensation filter and a PFIR matched filter which are connected in sequence. The system has good expansibility and modularization and can meet the requirements of real-time and high-speed performance.

Methods of and apparatuses for matching the signal delay, clock timing, frequency response, gain, offset, and/or transfer function of signal pathways in electrical circuits such as, for example, time-interleaved and pipelined circuits using analog-valued floating-gate MOSFETs are disclosed. The methods and apparatuses disclosed are applicable to a variety of circuits, including but not limited to, sample-and-hold or track-and-hold circuits, quadrature mixers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), analog or digital filters, and amplifiers.

The invention relates to a radio frequency receiving and transmitting front end for a millimeter wave holographic imaging security check system, which comprises a millimeter wave voltage-controlled oscillator, a millimeter wave low-nose amplifier and a millimeter wave quadrature mixer, wherein the millimeter wave voltage-controlled oscillator is connected with the millimeter wave quadrature mixer; the millimeter wave low-nose amplifier is connected with the millimeter wave quadrature mixer; the millimeter wave voltage-controlled oscillator is used for generating a millimeter wave radio frequency signal to be transmitted to a target and a local oscillation signal to be fed back to the millimeter wave quadrature mixer directly; the millimeter wave low-nose amplifier is used for receiving the radio frequency signal carrying the scatter amplitude and phase information of the target to perform low-noise amplification; and the millimeter wave quadrature mixer is used for performing the quadrature mixing of the millimeter wave local oscillation signal directly fed back by the millimeter wave voltage-controlled oscillator and the radio frequency signal amplified by the millimeter wave low-nose amplifier. In the invention, after necessary preamplification and digital sampling treatment of the output signal, the millimeter wave holographic image of the target can be restored by using a millimeter wave holographic algorithm.

Frequency conversion into a first intermediate frequency which is higher than a received frequency band is performed for a received signal by using a mixer and a PLL. Next, an output of the mixer is frequency converted into a second intermediate frequency of a base band by using a quadrature mixer formed by mixers and a phase shifter. At this time, a frequency of the local oscillation signal of a PLL supplied to the quadrature mixer is controlled so as to be switched, depending on a position of the received segment, between a frequency which is higher than the first intermediate frequency and a frequency which is lower than the same.

The invention relates to systems for receiving a digital radio signal and, more particularly, to receivers of radio signals, coded with a pseudo-noise sequence, which are used in global positioning system GPS (USA) and GLONASS (Russia), allowing a compensation effect for the narrow-band interference by using a device, controlled by the processor, with an automatic gain control, multilevel analog-to-digital converter, and additional correlation channel for detection of sinusoidal interference consisting of the digital generator having quadrature mixers and accumulators. Information from output of the of accumulators is read by a processor, in which is detected the presence (or absence) of interference, and the amplitude is evaluated. Therefore, the processor generates control signal directing amplification in the device using an automatic gain control.

A method and apparatus for frequency down-converting a radio frequency (RF) signal to baseband in two steps using the two quadrature components of a single local oscillator. In the first stage, the RF signal is mixed with both components of the local oscillator signal (LO) in a sub-harmonic mixer to produce an intermediate frequency (IF) output signal having a frequency component at twice the local oscillator frequency minus the RF frequency, i.e., (2×LO)−RF=IF. In the second stage, the IF signal is split into two and supplied to a quadrature mixer that mixes the IF signal with the I component of the same local oscillator signal and separately mixes the IF signal with the Q component of the same local oscillator signal to produce an output signal comprising an I component and a separate Q component at 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.

The invention discloses a frequency synthesizer and a frequency synthesis method. The frequency synthesizer comprises: a large-stepping phase lock loop and a direct digital frequency synthesizer, an orthogonal mixer and a tracking phase lock loop. The orthogonal mixer is connected with the large-stepping phase lock loop and the digital frequency synthesizer respectively for mixing the frequency generated by the large-stepping phase lock loop and the low frequency generated by the direct digital frequency synthesizer to generate a single-sideband single tone; the tracking phase lock loop is connected with the orthogonal mixer for receiving the single-sideband single tone output by the orthogonal mixer and filtering the sideband leakage and oscillation leakage of the signal. The invention provides a frequency synthesizer with wide band width, small stepping, low stray and low noise and a frequency synthesis method. The invention has simple hardware structure and is easy to accomplish.

A device and method for measuring phase and power shifts in a simultaneous dual polarization radar system comprises an access port, a quadrature mixer, and a power detector. The access port is configured to couple to the simultaneous dual polarization radar system near the antenna of the simultaneous dual polarization radar system. The quadrature mixer is configured to mix a first signal from a first polarization and a second signal from a second polarization. The first signal and the second signal are sampled through the access port. The first power detector is configured to measure the power level of the first signal.

The invention discloses a leakage signal cancellation circuit of a linear frequency modulation continuous wave radar. A transmission signal is transmitted by an antenna via a circulator; an input end of a first coupler is connected with the transmission signal; a through end of the first coupler is connected to the circulator; a coupled end of the first coupler is connected to an input end of a second coupler; a through end of the second coupler is connected to a signal input end of a vector modulator; a coupled end of the second coupler is connected to a phase shifter; the phase shifter is connected to an LO (Local Oscillator) signal input end of a quadrature mixer; leakage signal in the circulator is input to a third coupler; a through end of the third coupler is connected to a fourth coupler; a coupled end of the third coupler is connected with an output end of the vector modulator; a through end of the fourth coupler is connected to a receiver; a coupled end of the fourth coupler is connected to an RF (Radio Frequency) signal input end of the quadrature mixer; two differential signals output by the quadrature mixer are connected to the vector modulator via a differential operational amplifier, an active low pass filter and a summing circuit respectively; and the summing circuit and offset voltage carry out additive operation.

The invention discloses a software radio-based ultra-wideband digital satellite beacon receiving method and a receiver. The receiver comprises an ultra-wideband radio frequency front end and a digitalsignal processing module, whose signals are mutually communicated, and a power supply module for providing power for the ultra-wideband radio frequency front end and the digital signal processing module, wherein the ultra-wideband radio frequency front end includes a variable gain amplifier, a quadrature mixer, a local oscillator, an I-channel amplifier, an I-channel filter, an I-channel ADC, anda Q-channel amplifier, a Q-channel filter and a Q-channel ADC; the digital signal processing module includes a frequency calculation module, a power calculation module, and a control interface module. According to the method and the receiver, a digital signal processing method, and self-adaptive frequency adjustment and gain adjustment are used for carrying out precise frequency and power calculation on a satellite beacon signal, and outputting frequency and power information to an antenna controller to form an antenna turntable driving command to complete the alignment satellite process. Themethod and the receiver have the advanteges of ultra-wideband operation, large dynamic range, high integration, stable and reliable performance, strong universality and the like.

An orthogonal mixer generates first I and Q signals by down-converting an RF signal. A complex filter has an asymmetrical frequency gain property between a positive frequency domain and a negative frequency domain, and generates second I and Q signals by suppressing image signals included in the first I and Q signals compared with desired signals. An orthogonal compensation circuit is located at a subsequent stage of the complex filter, and corrects the second I and Q signals to cancel a phase difference error and an amplitude error of the desired signals between the second I and Q signals. Further, a control circuit adjusts an element characteristic of the complex filter to cancel a phase difference error and an amplitude error of the image signals that appear in the second I and Q signals.

The invention provides a wideband and low-phase noise local frequency synthesizing circuit. The wideband and low-phase noise local frequency synthesizing circuit includes a direct digital frequency synthesizer, frequency multipliers, low-pass filters, high-pass filters, a band-pass filter, a quadrature mixer, a mixer, amplifiers, an integer frequency divider, a phase discriminator, a loop filter, a voltage-controlled oscillator and a coupler. According to the wideband and low-phase noise local frequency synthesizing circuit of the invention, high phase discrimination frequency is adopted perform phase discrimination, and therefore, phase noise deterioration of a loop can be decreased; the loop adopts the integer frequency divider, and therefore, the effects of the mantissa of fractional frequency division on phase noises can be eliminated; baseband signals generated by the direct digital frequency synthesizer are subjected to quadrature up-conversion, so that high-resolution, low-phase noise and high-frequency signals can be generated, and the high-frequency signals and the output of the voltage-controlled oscillator are subjected to mixing down-conversion, and signals obtained after the down-conversion can become signals with large step. Since the output of the voltage-controlled oscillator and the high-resolution and low-phase noise signals are subjected to the down-conversion, the input frequency of the integer frequency divider can be reduced, and the frequency division ratio of integer frequency division can be decreased.

The present invention is a quadrature multi-mode RF receiver that uses a single quadrature mixer for tuning to desired frequency bands. In a direct conversion mode of operation, the RF receiver down converts a received RF signal directly into a baseband signal. In a VLIF mode of operation, the RF receiver down converts a received RF signal into a VLIF signal. When receiving a wanted RF signal, the frequency of the resulting VLIF signal is called the wanted VLIF frequency, and is based on the signal strength of the received RF signal. In one embodiment of the present invention, the wanted VLIF frequency is selected to be one of two VLIF frequencies. The wanted VLIF frequency is inversely related to the signal strength of the received RF signal.