169results about "Balance-unbalance networks" patented technology

A balanced high-frequency device is constituted by a balanced device and a phase circuit. The input side of the balanced device is connected to an input terminal IN serving as an unbalanced input / output terminal and the output side of it is connected to output terminals OUT1 and OUT2 serving as balanced input / output terminals. Moreover, the phase circuit is connected between the output terminals.

An unbalanced-balanced multiband filter module comprising three high-frequency switches each comprising a switching element, and two unbalanced-balanced bandpass filters having different transmitting frequency bands, a first high-frequency switch being connected to an unbalanced port of the module, an unbalanced port of the first unbalanced-balanced bandpass filter, and an unbalanced port of the second unbalanced-balanced bandpass filter; a second high-frequency switch being connected to a first balanced port of the module, a first balanced port of the first unbalanced-balanced bandpass filter, and a first balanced port of the second unbalanced-balanced bandpass filter; a third high-frequency switch being connected to a second balanced port of the module, a second balanced port of the first unbalanced-balanced bandpass filter, and a second balanced port of the second unbalanced-balanced bandpass filter; and the first to third high-frequency switches being switched depending on a passing high-frequency signal, whereby a high-frequency signal input into an unbalanced port of the module is output from the first and second balanced ports, or a high-frequency signal input into the first and second balanced ports is output from an unbalanced port of the module.

In a first aspect, an RF switch includes a main transistor and a gate-to-source shorting circuit. When the RF switch is turned off, the gate-to-source shorting circuit is turned on to short the source and gate of the main transistor together, thereby preventing a Vgs from developing that would cause the main transistor to leak. When the RF switch is turned on, the gate-to-source shorting circuit is turned off to decouple the source from the gate. The gate is supplied with a digital logic high voltage to turn on the main transistor. In a second aspect, an RF switch includes a main transistor that has a bulk terminal. When the RF switch is turned off, the bulk is connected to ground through a high resistance. When the RF switch is turned on, the source and bulk are shorted together thereby reducing the threshold voltage of the main transistor.

A frequency shift-keying reader circuit includes a band-pass filter, a low noise amplifier, a first balun, an injection-lock divide-by-2 frequency divider, a sub-harmonic mixer and a low-pass filter. The band-pass filter performs a filtering procedure to a radio frequency signal, wherein the filtered radio-frequency signal is received by the low noise amplifier to provide an injection signal, and the injection signal is received by the first balun to generate a first differential signal and a second differential signal. The injection signal is received by the injection-lock divide-by-2 frequency divider to provide a first oscillation signal and a second oscillation signal, wherein the first differential signal, the second differential signal, the first oscillation signal and the second oscillation signal are received by the sub-harmonic mixer for performing a mixing procedure and thereafter generating an output signal, the low-pass filter performs a filtering procedure to the output signal.

An integrated receiver circuit includes a phase locked loop circuit (21) with a voltage controlled oscillator (VCO) (25) and a quadrature generator circuit (29) which uses hybrid-branch line coupler circuits (27, 28) coupled to buffered VCO outputs, where the hybrid-branch line coupler circuits (27, 28) are tuned by same control voltage (25a) that controls the VCO (25). By replicating the VCO core circuitry in each hybrid-branch line coupler circuit (27, 28) under common control of a control voltage, calibrated quadrature signals are generated that have the same frequency as the phase locked loop circuit (21).

A hybrid balun apparatus are disclosed. The hybrid balun apparatus can support both the reception mode and the transmission mode and be advantageous for a high level of integration, by replacing two transformers disposed at a reception path and a transmission path with a single transformer and integrating a T / R switch and a balun into a one chip. Therefore, an IC according to integration extends to a front stage of an antenna to facilitate interfacing between elements, and a burden for designing at a rear stage (i.e., LNA in the reception mode, and PA in the transmission mode) can be reduced.

A broadband active balun configuration is provided. According to embodiments, the subject active balun can include a cascade and cascade transistor pair using a shared input transistor. In a further implementation, a low-pass bias-feedback mechanism for maintaining stable bias conditions can be provided.

Provided is a wideband active balun circuit based on a differential amplifier. The active balun circuit is configured to compensate for unbalance between two differential signals and can be applied to wideband systems, such as software defined radio (SDR) systems or ultra wideband (UWB) systems. Also, when signal unbalance is caused by changes in process conditions, such as temperature, errors in amplitude and phase between the two differential signals can be finely tuned by adjusting a voltage tuning terminal outside a chip, so that the active balun circuit can simply solve the unbalance between the two differential signals. Furthermore, input transistors that constitute a pair of differential amplifiers are provided in a cascode structure to prevent the occurrence of signal leakage and self-mixture.

An integrated balun includes a low pass filter and a high pass filter that are formed on a semiconductor chip using tunable reactive elements. The outputs of the low pass filter and the high pass filter are tied together to form the single ended output of the balun. The inputs of the low pass filter and the high pass filter form the differential inputs of the balun. The low pass filter and the high pass filter each include a number of tunable networks for achieving the tunable reactive elements. Each tunable network includes at least one switching transistor and at least one fixed value reactive elements. In at least one embodiment, dynamic biasing circuitry may be provided to improve the linearity and reduce the insertion loss of the balun.

A balanced high-frequency device is constituted by a balanced device and a phase circuit. The input side of the balanced device is connected to an input terminal IN serving as an unbalanced input / output terminal and the output side of it is connected to output terminals OUT1 and OUT2 serving as balanced input / output terminals. Moreover, the phase circuit is connected between the output terminals.

A balun transformer includes a first conductive pattern having one end provided as an input / output port of an unbalanced signal, a second conductive pattern electromagnetically coupled to the first conductive pattern and having both ends provided as input / output ports of a balanced signal, and a first variable capacitor connected between a ground part and a middle part of an electrical length of the second conductive pattern.

In a filter module, a common input / output portion of a switch circuit is set as a first port. A first filter arranged to pass a signal in a first frequency band is connected between a first input / output portion of the switch circuit and a second port. A second filter arranged to pass a signal in a second frequency band is connected between a second input / output portion and the second port. A phase adjusting circuit is provided such that an impedance in the second frequency band as seen from the first port while the switch circuit selects the first input / output portion is in a substantially short-circuited state. This arrangement prevents leakage of unwanted signals from a signal path used in a communication system not in operation among two communication systems for different frequency bands while the other communication system is engaged in communication.