Abstract: Systems and methods for DC offset correction in analog and digital direct conversion RF receivers. A time derivate and subsequent integration of in-phase and quadrature phase signal path components is performed to effectively remove DC offset from the resultant down converted baseband signal.

Abstract: A remote control transceiver is described. The remote control transceiver reduces costs by simplifying a structure of a conventional space movement remote controller including an acceleration sensor, a microprocessor, a radio transmitting unit, and a radio receiver. A grid pattern formed by a light emitting diode (LED) and an optical system of a transmitter is determined by an infrared sensor of a receiver to discern space movement location information of the transmitter. The remote control transceiver includes a remote control transmitter and a remote control receiver. The remote control transmitter includes a key input unit for receiving commands, an LED driver for controlling the operation of an LED in response to a command signal generated from the key input unit, and a pattern generator for generating a grid pattern using light generated from the LED.

Abstract: A bit error rate of the reception signal is detected on the reception side, such that an n optimal modulation method and LO output power are determined in accordance with this bit error rate, and an LO output changing instruction is sent to an image signal rejection mixer on the transmission side. The image signal rejection mixer changes the phase X=?+? in response to the LO output changing instruction when power splitter (201) splits the LO into two components with equal amplitude and phase difference ?, power splitter (202) splits the IF signal into two components with equal amplitude and phase difference ?, and power combiner (205) combines RF signals with equal amplitude and phase difference ?. By changing the X, the LO output power is controlled and the back-off amount of a transmission amplifier is changed in accordance with an optimal modulation scheme. In this event, ???+?=2n? (n is an integer) is set so as to maximize the image signal rejection amount.

Abstract: A switched current resistor (SCR) PGA for constant-bandwidth gain control includes an inverting amplifier, a feedback resistor forming a feedback loop between an output side and an input side of the inverting amplifier, and a switched current resistor (SCR) array connected in parallel to the feedback resistor, and configured to tune a gain range between a maximum and a minimum. The SCR array includes a plurality of switched resistors, each comprising a switch in series with a resistor. When the plurality of switched resistors are switched by a gain-control logic, a plurality of switched current sources and a plurality of grounded resistors are switched correspondingly to deliver a transient current, an equivalent of which flows through the plurality of grounded resistors out from the input side of the inverting amplifier, leading to a feedback factor of the PGA being constant.

Abstract: A receiver includes an antenna array, an angular positioning module, a low noise amplifier module, and a down conversion module. The antenna array is operable to receive an inbound wireless signal. The angular positioning module is operable to: receive a plurality of received inbound wireless signals from the antenna array; determine angular position of a source of the inbound wireless signal from at least some of the plurality of received inbound wireless signals based on a first radiation pattern and a second radiation pattern of the plurality of received inbound wireless signals; and output a representation of the inbound wireless signal. The low noise amplifier module is operably coupled to amplify the representation of the inbound wireless signal to produce an amplified inbound wireless signal. The down conversion module is operably coupled to convert the amplified inbound wireless signal into a baseband or near baseband signal.

Abstract: A RF device such as a tower mounted amplifier (TMA), mast-head amplifier (MHA), or Tower Mounted Boosters (TMB) includes a housing having a plurality of cavities and an input and an output, the input being coupled to the antenna and the output being coupled to a base station. The housing includes a transmission path holding multiple coaxial resonators. The housing further includes multiple receive paths including at least one path having a plurality of cavities, each cavity containing a dielectric resonator. The metallic transmit resonator nearest the antenna input is coupled to the first dielectric resonator via a common resonant wire. The last dielectric resonator in the receive path is coupled to a first metallic resonator of a downstream clean-up filter via another common resonant wire.

Abstract: A RF differential gain stage has cross-coupled capacitors between input and output nodes of the amplifier stage to boost gain. The gain boost allows cancellation of the series resistance of an inductive load of the amplifier stage.

Abstract: Techniques are described that can be used to reduce interference in a desired channel by one or more other channels. A radio includes a level detect logic that is responsive to both the frequency offset and amplitude of undesired signals and sets the gain applied to received signals based on the offset frequency and determined amplitude of undesired signals. For example, detection of a signal amplitude in an interfering signal in a channel adjacent to the desired channel may be made. Detection of a signal amplitude in an interfering signal in a channel other than the adjacent channel and desired channel may also be made. Based on detection of one or more interfering channel, a gain of an input signal may be adjusted. Interference arising from at least spectral re-growth of noise and clipping noise may be reduced.

Abstract: An apparatus for controlling transmission power of a mobile communication terminal. The apparatus comprises a central processing unit for measuring a power level of a received signal and determining a power amplification mode in response to the measured power level of the received signal and a power preset table, a driver amplifier for amplifying a transmission signal to produce an output signal, the driver amplifier has operating conditions chosen in accordance with the power amplification mode, a voltage converter for outputting a preset voltage value in accordance with the power amplification mode, and a power amplifier for amplifying the output signal of the driver amplifier in response to the outputted preset voltage value.

Abstract: A radio frequency receiver 30, 32, includes a first component block 12, 16, 18, 20; a second compensating component block 22, 22a-22b, 34; and control circuitry 26 operable for controlling the state (e.g., load, bias, gain) of the first component block. When the control circuitry 26 causes a change in the state of the first component block that is expected to induce a DC offset in a signal, the control circuitry 26 changes the state of the second component block to compensate for an estimate of the DC offset. Preferably, the second component block is a filter 22, 22a-22b, 34, that temporarily changes from a nominal cutoff frequency to an elevated cutoff frequency so that voltage will settle quickly and accurately at an estimated voltage, the estimated voltage being predetermined and based on the state change to the first component block. A method is also described for practicing the invention.

Abstract: Methods, apparatus, and articles of manufacture are disclosed for removing an undesired component from a low intermediate frequency signal having an intermediate center frequency and an undesired component at a first frequency. One example method may include determining an amplitude of the undesired component; frequency shifting the low intermediate frequency signal from the intermediate center frequency to produce a zero intermediate frequency signal; filtering the zero intermediate frequency signal; generating a tone based on the amplitude of the undesired component; and subtracting the tone from the filtered zero intermediate frequency signal to remove the undesired component.

Abstract: A method and system for increasing the compression point of a receiver by deriving a feedback signal from mixer output signals. The feedback signal prevents the receiver from going into compression on strong out-of-band or blocking signals, while enhancing the receiver gain at the desired frequency. The desired frequency coincides with the local oscillator (LO) signal and is therefore particularly applicable for, but not limited to, homodyne receivers where selectivity can be made quite narrowband. Since the selectivity is coupled to the LO, a tunable receiver may be achieved that enables selectivity over a wide range of input frequencies.

Abstract: A receiver includes a low noise amplifier (LNA) and multiple pairs of mixers. The LNA receives and amplifies an LNA input signal and provides at least one LNA output signal. Each pair of mixers downconverts one of the at least one LNA output signal when enabled. Each pair of mixers may be selectively enabled or disabled, e.g., based on a mode selected from among multiple modes. In one design, the LNA includes multiple load sections coupled in parallel. Each load section may be selectively enabled or disabled, e.g., based on the selected mode. In one design, first and second pairs of mixers and first and second load sections may be enabled for a high linearity mode. The first pair of mixers and the first load section may be enabled and the second pair of mixers and the second load section may be disabled for a low linearity mode.

Abstract: A wireless communications receiver includes a memory configured to store offset values corresponding to respective gain settings. A gain controller is configured to continuously select one of the gain settings based on amplitude of a received signal. An amplifier is configured to amplify the signal based on the selected gain setting. An offset estimator is configured to determine an updated offset value as a function of both a time-average value of the signal and a previously-stored offset value. The previously stored offset value is an offset value that was stored in the memory at a time prior to the gain controller switching to the currently-selected gain setting from a previously-selected gain setting.

Abstract: The invention relates to a preamplifier circuit with at least one transistor that couples a signal input to a signal output. The signal input is supplied with a radio-frequency signal. In addition, the preamplifier circuit includes a switch that switchably couples the input to a reference potential and which, when the preamplifier is inactive, is closed. Hence, when the preamplifier is inactive, the input is put into a low-impedance state and the amplifier and downstream assemblies are protected from unwanted high-power interference signals. It is thus also possible to use other, fully integratable filter types in a transceiver's reception signal processing chain instead of external surface acoustic wave filters with a low level of complexity and without drawbacks.

Abstract: A method (10) and system (50 or 200) of using a credit card media type (54) integrated with a wireless communication device (52) can include determining (12) that the wireless communication device is inoperable for use in a commercial transaction and enabling (14) the use and authorization of the credit card media type with a predetermined restriction profile that is more restrictive than when the credit card media type is used with the wireless communication device when operable. The method can lower (16) the payment authorization amount or limit a type of item that is purchased to a predefined type based on a remote network being unable to communicate with the wireless communication device. The method can also remove (18) the credit card media type from the communication device and enable the use and authorization of the credit card media type with the predetermined restriction profile.

Abstract: 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.

Abstract: A multimode receiver/down converter architecture for use with narrow channel bandwidth and channel bandwidth system signals is described. Interfering signals for a selected narrowband channel are attenuated using a method that reduces the dynamic range of the signal for further processing. The proposed method can be used with a receiver architecture, such as Direct-Conversion, low IF, Super heterodyne, and the like. The downconverted signal is split into two paths. One signal path is delayed and subtracted from the signal from the other path. By controlling the delay value, the interference signals at a given offset are attenuated. Based on the chosen architecture, the desired signal is placed so that the signal undergoes minimal distortion.

Abstract: A direct conversion television receiver may include a phase de-rotator which substantially undoes the phase rotation of a phase rotator. The phase de-rotator takes the low pass filtered signal and substantially removes the rotation caused by the phase rotator. As a result, it is easier to estimate the phase and gain imbalance and to make a correction for the phase and gain imbalance, via a feedback loop, without the effects of phase rotation.

Abstract: The invention relates to a receiver in a radio system that contains receiving means for receiving a signal, amplification means for amplifying the received signal with an amplification step, and means for limiting the frequency band of the amplified signal. The receiver also contains correction means for correcting the step response of the limiting means by using step response information defined in advance. The invention also relates to a method for correcting the step response.

Abstract: Broadcast signal-receiving apparatus and a method filtering noise signals. The broadcast signal-receiving apparatus includes a tuner to convert an RF signal to a lower frequency signal to output an intermediate frequency (IF) signal, a filter to filter the IF signal to output a digital IF signal, and a controller to control the tuner to shift a frequency of the IF signal to a frequency band to remove the noise signals if the digital IF signal contains noise signals of a predetermined magnitude. Accordingly, the broadcast signal-receiving apparatus can filter the noise signals resulting from analog and digital broadcast signals adjacent to a digital broadcast signal on a channel selected for viewing.

Abstract: DC power savings in a mobile communication device can be achieved by dynamically adjusting the biasing for a receiver based on the communication link quality. The output signal levels of at least one low noise amplifier (LNA) are monitored to identify the DC operating conditions for the LNA. Closed loop control of the DC biasing is adjusted based on a comparison between the monitored DC operating conditions and a reference signal. The output of the LNA is also coupled to a radio receiver section that is configured (e.g., SW or HW) to evaluate the link quality based on various criteria such as inter-modulation distortion, noise, interference, fading, etc. The reference signal that is used to control the DC biasing of the LNA is adjusted (periodically, continuously, or on demand) in response to the evaluated link quality. The dynamic biasing yields acceptable signal reception with low DC power consumption.

Abstract: The method and apparatus of the present invention provide for a configurable radio front end topology that allows selectable operation in a single balanced mode and in a double balanced mode of operation. Logic associated with a baseband processor determines whether to operate in a single or double balanced mode of operation and produces the mode control signal to control selective coupling of circuit components according to the specified mode. Switching circuitry is used to switch a Balun in and out of connectivity. Further, a pair of LO polarity blocks are operable to determine the polarity of a differential LO received by associated mixers according to whether a single balanced or double balanced mode is in use.

Abstract: Methods and systems are disclosed that mitigate stereo noise in FM broadcast receivers by assessing L?R (left-minus-right) and L+R (left-plus-right) levels within tuned FM channels. These assessments are used to facilitate control of a blend from stereo output signals to mono output signals in order to reduce and mitigate stereo noise and distortion in the audio outputs. The side effects of the disclosed systems and methods are unobtrusive as compared to prior blend-to-mono techniques.

Abstract: In one embodiment, the present invention includes a method for digitizing a phase noise value indicative of a level of phase noise present in a LO signal and downconverting an RF signal to a second frequency signal using the LO signal. This downconversion can cause the phase noise to be transferred to the second frequency signal. The method may thus further include removing the phase noise from the second frequency signal using the digitized phase noise value.

Abstract: Systems and methods for DC offset correction in analog and digital direct conversion RF receivers. A time derivate and subsequent integration of in-phase and quadrature phase signal path components is performed to effectively remove DC offset from the resultant down converted baseband signal.

Abstract: A low-noise block converter comprises a low-noise amplifier, a local oscillator, a mixer, an IF-amplifier and a regulator. The low-noise amplifier amplifies a high-band received signal. The local oscillator generates a local-frequency signal. The mixer transforms the high-band received signal into an intermediate-frequency signal by mixing the high-band received signal with the generated local-frequency signal. The IF-amplifier amplifies the intermediate-frequency signal. The regulator is connected to the IF-amplifier to provide a steady current (or voltage) to the local oscillator, the mixer and the low-noise amplifier.

Abstract: A method and system for diversity transmission from a mobile station. Signals sent from a mobile station to a base station may suffer from fading. To combat this, diversity transmission is used to compensate for the effects of fading and destructive multi-path interference by sending two or more signals. Signals to be transmitted from the mobile station are split into a first split signal and a second split signal and diversified from one another. Diversification of the split signals may be accomplished by modifying the phase of either the first split signal, the second split signal or both the first and second split signal. The diversified signals may then be transmitted from a first and second antenna.

Abstract: An apparatus for demodulating a modulated signal comprises an analog to digital converter (2, 12) for converting an analog modulated input signal to a digital signal. The analog to digital converter is arranged to sample the input signal at a predetermined sampling rate. A digital down converter (4, 14) then receives the digital signal at the sampling rate. The digital down converter has an associated digital intermediate frequency and reduces the frequency of the digital signal to one quarter of the sampling rate. A low pass filter (6, 16) filters selected frequencies from the digital signal. A frequency offset stage (8, 18) applies a modification to the frequency of the filtered signal to reduce frequency offset therein, and a differential demodulator (10, 20) demodulates the signal after modifying the frequency to reduce the frequency offset. There is also disclosed a method for demodulating a signal.

Abstract: In an aspect of the invention, a method is performed in a transceiver for adaptive power amplifier linearization in time division duplex communication systems. The method comprises, in response to a first condition, performing, using a feedback signal generated by receiving subsystem circuitry, adaptive power amplifier linearization on a signal to be transmitted. The method additionally comprises, in response to a second condition, performing operations in order to determine receive data from a received radio frequency (RF) signal. The operations use at least the receiving subsystem circuitry. In a further aspect of the present invention, a transceiver is disclosed.

Abstract: A method and device for transmitting data in the form of a series of blocks in which each block of data is subjected to a frequency conversion in order to be transmitted at a carrier frequency. The method includes inserting a sequence of padding data between a first block of data intended to be transmitted at a first carrier frequency and a second block of data intended to be transmitted at a second carrier frequency, and transmitting the padding data while the frequency changes from the first carrier frequency to the second carrier frequency.

Abstract: An RF circuit module, in which a power amplifier and a transceiver are united, with reduced interference between its electronic circuit blocks, downsized and still having high performance, and with a stable performance not dependent on the ground land structure on the motherboard, is provided. The ground plane 110 for at least a last-stage amplifier 11 of the power amplifier 10 where the greatest power is generated in the whole RF circuit block, that is, the source of generating the greatest noise and heat for the RF circuit block, is isolated from the ground plane for at least one circuit portion of the transceiver 9 including an LNA 51, receiver 52, transmitter 30, and VCO 70. These ground planes are connected to a common ground plane 480 through different connection conductors, respectively.

Abstract: A feedforward error-compensated receiver for minimizing undesired odd-order nonlinear distortion products. The receiver includes a first receiver path configured to receive an input signal. The first receiver path outputs a signal including at least one baseband (BB) frequency. At least one second receiver path is configured to receive the input signal and to provide a second receiver path output signal. The second receiver path includes at least one odd-order nonlinear distortion reference generator. The at least one odd-order nonlinear distortion reference generator and the mixer are configured to generate a synthetic odd-order nonlinear distortion signal. A combining element is configured to receive the output signal from the first path and the output signal from the second receiver path output and to combine the signals such that the odd-order nonlinear distortion signals are substantially attenuated at an output of the combining element.

Abstract: A communication system may include an equalizing device for DC-offset mitigation. The system includes: an input analog-to-digital converter configured to receive an input signal and produce a digital signal from the input signal; and a DC-offset estimation device coupled with the input analog-to-digital converter. The DC-offset estimation device is configured to produce a quantized DC-offset estimate from the digital signal. And the input analog-to-digital converter is configured to receive the quantized DC-offset estimate and to adjust a DC offset of the digital signal.

Abstract: In a slot format of a received signal, AGC gain update timings (t1 to t4) are shifted every time to disperse and reduce an influence of a noise attributable to a direct current component specific to direct conversion which is accompanied by AGC gain update. In particular, in the case where each of slots in the received signal includes an information portion (data) having a larger code correcting capability and an information portion having a smaller code correcting capability (TPC (transmission power control), TFCI (transport format combination indicator), PILOT), the AGC gain update timing is generated while being shifted in the former information portion, thereby reduce the influence of the noise. When the amount of shift of the AGC gain update timing is set to be larger than that of one symbol of the received signal, the influence of the noise accompanied by the AGC gain update is further reduced.

Abstract: In a receiver, a mixer portion provided in a front-end portion thereof is built with two mixers with different input/output linearity characteristics and different current consumption. According to the electric-field strength of a received signal, or manually, one of the mixers is chosen to operate so that, when the electric-field strength is in an ordinary range, the mixer with a better input/output linearity characteristic is chosen to operate with lower current consumption and, when the electric-field strength is in a high range, the mixer that, despite operating with higher current consumption, exhibits a still better input/output linearity characteristic is chosen. The receiver thus operates with lower current consumption and lower signal distortion.

Abstract: Embodies of peripheral a wireless relay system apparatus and method for a multi-path interference removing using by same channel frequency is shown and described, which purpose of the present invention is to overcome extension of service coverage and a dead spot with amplifying same channel frequency, a problem in doing the relay, system wireless relay system was a same frequency interference of RF (Radio Frequency) output is become feedback radiating from tx antenna to rx antenna of the relay system, the wireless relay system apparatus and method effectively eliminates the same frequency interference so that it can ensure an additional system gain and easy to set up relatively to general same frequency relay system.

Abstract: Variations in characteristics due to individual differences among RFs cause differences between estimated noise spectrum patterns and actually occurring noise characteristics, resulting in variations in noise suppression capabilities. A pattern table stores, in advance, a spectrum pattern of a noise component contained in an audio signal and which is determined for each electric field strength. A noise estimation unit reads out a noise spectrum pattern corresponding to an electric field strength and estimates a noise component contained in an audio signal. A level calculation unit uses a test signal corresponding to a predetermined electric field strength as input to calculate a noise level contained in an audio signal obtained by an FM demodulation unit. A correction value calculation unit uses the calculated noise level to correct the association between the noise spectrum pattern and the electric field strength.

Abstract: In a video IF channel the gain of the circuit is achieved ahead of the IF filter and the output of the filter, including its noise, need only be amplified a relatively small amount, thus preserving an acceptable signal to noise ratio. In one embodiment, a variable gain amplifier is used as the first stage amplifier and a fixed gain amplifier is used for the output stage.

Abstract: The RSSI circuit of the present invention includes: an IF amplifier section, which includes multiple stages of serially connected differential amplifiers for amplifying, with use of a current source IA provided as a power source for amplification, an IF signal corresponding to a received signal; an RSSI amplifier section for converting into current a voltage amplitude of an absolute value signal outputted from the differential amplifiers of the IF amplifier section, using a current source IB provided as a power source for conversion, and adding and outputting the converted current; and a current voltage conversion circuit for converting into voltage the output current from the RSSI amplifier section, and outputting the converted voltage as a measurement voltage value. The RSSI amplifier section is set so that a current value of the RSSI amplifier section is inversely proportional to absolute temperature.

Abstract: Aspects of a method and system for a transformer-based high performance cross-coupled low noise amplifier may include one or more circuits that integrate within a single chip, a balun with a low-noise amplifier. A DC current biasing path for the low-noise amplifier may be provided through the integrated balun. The low-noise amplifier may be configured as a cross-coupled low-noise amplifier, where the balun may be directly coupled to the cross-coupled low-noise amplifier. The balun may comprise two or more inductors, wherein one or more of the inductors may provide an electrical path for allowing a DC bias current to flow to ground. Integrating a balun on a single chip with a low-noise amplifier may allow the use of a single received signal input terminal. The biasing voltage may be selected to optimize performance of the low-noise amplifier.

Abstract: Aspects of a method and system for sharing low noise amplifier (LNA) circuitry in a single chip Bluetooth and wireless local area network (WLAN) system are disclosed. Aspects of the system may comprise a chip with integrated WLAN and Bluetooth radios. RF signals may be received via a single antenna coupled to a shared LNA integrated in chip. When WLAN signals are received they are communicated from the shared LNA to a subsequent amplification stage integrated within the WLAN radio. When Bluetooth signals are received they are communicated from the shared LNA to a subsequent amplification stage that comprises a transconductance amplifier integrated within the WLAN radio and an LNA load integrated within the Bluetooth radio. Gains in the LNAs, the transconductance amplifier, and/or the subsequent WLAN amplification stage may be dynamically adjusted. Outputs from the subsequent amplification stages may be communicated to mixers for further processing.

Abstract: In a radio communication system having a phase control loop for phase modulation and an amplitude control loop for amplitude modulation and being capable of time divisional transmission and reception under a predetermined time management, when transmission in a first mode is switched to transmission in a second mode or when transmission in the second mode is switched to transmission in the first mode, the output level of the power amplifier is lowered once to a predetermined level higher than the level when transmission related circuits are activated, and thereafter the output level of the power amplifier is again ramped after the settings have been changed but without starting of a transmission oscillator, establishing of the phase control loop and the amplitude control loop.

Abstract: A dynamically matched mixer system (200) for use in a direct conversion radio frequency (RF) receiver includes a frequency generator (201, 203, 205) that includes plurality of dividers (407) for providing differential local oscillator reference sources (FLO+ and FLO?) and mitigation frequency reference sources (F1 and F2) from reference oscillator (205). A mixer (209) mixes the differential local oscillator reference sources (FLO+ and FLO?) and the mitigation frequency reference sources (F1 and F2) while dynamic matching units (211, 213) are used for receiving the mitigation frequency reference sources and matching switching parameters of differential input signals (IRF+ and IRF?) and differential baseband output signals (IBB+ and IBB?). The frequencies of the mitigation frequency reference sources (F1 and F2) are selected so as to establish a non-integer relationship to the reference oscillator (201) for mitigating the occurrence of interference with FLO+ and FLO?.

Abstract: An amplification system for reducing DC offset in an input signal uses a low pass filter to isolate a DC component of the input signal. The system then subtracts the DC component from the input signal. In one embodiment, the system includes first and second amplifiers in addition to the low pass filter. The first amplifier amplifies the input signal to generate a first amplified signal at a differential output port of the amplification system. The second amplifier amplifies a low pass filtered version of the input signal to generate a second amplified signal at the differential output port of the amplification system. The outputs of the first and second amplifiers are connected to the differential output port of the amplification system in such a way that the first and second signals combine 180 degrees out of phase at the output port.

Abstract: A high frequency device includes a transmission/reception amplifier 13 that amplifies and outputs an input signal, and a transmission/reception switch 2 that gang switches internally so that during transmission an input of the transmission/reception amplifier 13 is connected to an up mixer and an output of the transmission/reception amplifier 13 is connected to an antenna unit 5, and so that during reception the output of the transmission/reception amplifier 13 is connected to a down mixer and the input of the transmission/reception amplifier 13 is connected to the antenna unit 5.

Abstract: A method and circuit to eliminate an offset noise, which may be produced at or near DC (zero Hertz) in an analog, linear multiplier, is described. An input signal is chopped (converted to another frequency) by a first chopper, shifting a frequency of the input signal such that the multiplier output signal is shifted away from DC. An output signal of the multiplier is subsequently chopped again by a second chopper employing the same chopping frequency as the first chopper. This converts a frequency of the output signal to a desired frequency at or near DC. The double chopping also shifts the offset noise produced by the multiplier to a frequency, that is higher than the frequency of the output signal. The offset noise can then be removed by a low-pass filter leaving the output signal without the offset noise.

Abstract: A current restriction structure for restricting a higher-harmonic-wave current generated in a digital circuit block from entering a radio circuit block and/or a radio-frequency current generated in the radio circuit block from entering the digital circuit block is disposed between the radio circuit block and the digital circuit block. The current restriction structure is formed by one or two of equivalent rectangular cylindrical metallic tube including metallic planes overlying/underlying the ground layer and a narrow-pitch via-hole array, which are disposed to enclose the subject current to be restricted and have a short-circuited distal end. The distance between the open plane of the equivalent rectangular cylindrical metallic tube and the short-circuiting plate is set at ¼ of the wavelength of the subject current to be restricted.

Abstract: Heretofore, a plurality of packages were used in a high frequency module in which a plurality of waveguide terminals were positioned resulting in problems, such as degradation of characteristics in the connection lines between packages, lower ease of assembly when mounting and connecting the connection lines, increased cost, and so forth. To solve these problems, a plurality of cavities having a part or the entire side metallized is formed in a multi-layer dielectric substrate. The multi-layer dielectric substrate is provided with a plurality of waveguide terminals, microstrip line-waveguide converters, RF lines, bias and control signal wiring, and bias and control signal pads. A high frequency circuit is mounted within the cavity and sealed with a seal and cover. This is intended to reduce the number of package, improve performance, improve fabrication, and lower the cost.

Abstract: An amplifier circuit for amplifying an input signal to generate an amplifier output signal incorporates a cascaded series of reflection amplifiers arranged along a signal path and operative to amplify signals propagating in a forward direction along the signal path. The circuit is operative to counteract signal propagation in a reverse direction along the signal path, thereby hindering spontaneous oscillation from arising within the circuit. Incorporation of reflection amplifiers into the circuit enables it to provide high gain, for example 50 dB, while consuming low currents, for example, tens of microamperes. The circuit is especially suitable for use at intermediate frequencies in radio receivers such as mobile telephones.