摘要:
The present invention provides a communication apparatus (RFIC) capable of performing a DC offset correction of an orthogonal modulation unit with a degree of accuracy higher than conventional. The orthogonal modulation unit of the RFIC includes first and second mixers, an adder and first and second switches. The first mixer receives a first local oscillation signal therein through the first switch. The second mixer receives a second local oscillation signal therein through the second switch. During calibration, a DC offset of the first mixer is adjusted in a state in which the first switch is brought to an ON state and the second switch is brought to an OFF state. Further, a DC offset of the second mixer is adjusted in a state in which the first switch is brought to an OFF state and the second switch is brought to an ON state.
摘要:
The present invention provides a semiconductor device. In the semiconductor device, a signal distributor distributes a high frequency signal generated by an oscillator and inputted to an input part to first and second signals and outputs the same from first and second output parts respectively. A modulator modulates a baseband signal with the first signal and outputs the same therefrom. An offset adjustment unit compares the second signal and the first signal that leaks from the output of the modulator to thereby adjust an offset of the baseband signal. The signal distributor includes a first capacitive element provided between the input part and the first output part, and a second capacitive element provided between the first output part and the second output part. The electrostatic capacitance of the first capacitive element is larger than that of the second capacitive element.
摘要:
A semiconductor device for transmitting-signal amplification which has a fine resolution, a high dynamic range, a small occupied area, and low power consumption, is realized. An input signal amplitude is reduced every one half by a ladder network, and a transconductance amplifier stage is arranged corresponding to each node of the ladder network. An output of the transconductance amplifier stage is coupled to an output signal line in common. According to a control word WC , the transconductance amplifier stage is enabled selectively, and the output current which appears in the output signal line is added.
摘要:
A wireless LAN system has auto gain control with no work load applied to its baseband processing block. When the wireless LAN system gets ready to receive a signal, the gain control circuit switches between the receiving antennas. The gain control circuit sets gain setting value time divisional data according to the level of a received signal to roughly control the gain to be set in the LAN and the gain to be set in two programmable gain amplifiers.
摘要:
In a direct conversion receiver, to cancel a DC offset generated in the baseband processing block, negative feedback arrangements comprising a gain control amplifier and a low-pass filter are respectively attached to the I and Q signal branches of the baseband block following mixer outputs. The gain control amplifier in each negative feedback circuit is gain adjusted so that the product G-B of the gain G of a primary gain control amplifier and its own gain B will be constant and thereby the DC offset is cancelled. This DC offset cancellation can be applied in a continuous receiving system with no intermittent time during a receiving operation. Capacitance elements located off-chip can be reduced to those to be used only in the low-pass filters in the negative feedback circuits, whereas many off-chip capacitance elements have been required to be inserted between each stage of gain control amplifiers in conventional baseband chains.
摘要:
There is provided an LC resonance type oscillation circuit with a wide frequency variable range with a small variation of Q and capable of reducing a chip size due to no external parts required, and a communication semiconductor circuit device (high-frequency IC) having the oscillation circuit. In the LC resonance type oscillation circuit, a capacitance element and a switch element are connected in parallel between both terminals of a secondary side inductance element which is placed facing an inductance element constituting the LC resonance circuit and is connected by mutual induction to the inductance element. It is designed so that an equivalent inductance increases as the capacitance element is connected between the both terminals of the secondary side inductance element in a state where the switch element is turned OFF, and that the equivalent inductance decreases as the both terminals of the secondary side inductance element are short-circuited in a state where the switch element is turned ON.
摘要:
The dynamic range is changed by switching a current applied to an amplifying circuit to obtain the minimum ICP required to keep linearity with the number of multiplexes even when the number of multiplexes of data is changed by switching the operation current of the amplifying circuits of the transmission system and also supplying the information about number of multiplexes of data to be transmitted to the amplifying circuits of the transmission system from the baseband circuit. Thereby, the signal can be transmitted without distortion even when the number of multiplexes increases and the current of the amplifying circuit may be reduced when the number of multiplexes is small in order to reduce the current consumption in the communication semiconductor integrated circuit device which can form a wireless communication system of the code division multiplex system such as W-CDMA system.
摘要:
A variable gain amplifier circuit includes output nodes, a plurality of amplifiers, and a detection circuit. The amplifiers are coupled in parallel with each other between the output nodes and a reference node and selectively assume an operating state in accordance with a control signal. The detection circuit outputs a detection signal according to the magnitude of an input signal to each amplifier. Each amplifier includes a first transistor, a second transistor, and a bias circuit. The first transistor receives, at its control electrode, the input signal or a signal proportional to the input signal. The second transistor is series-coupled to the first transistor between the first reference node and an output node. The bias circuit applies a DC voltage of a magnitude according to the detection signal to a control electrode of the second transistor.
摘要:
A semiconductor device for transmitting-signal amplification which has a fine resolution, a high dynamic range, a small occupied area, and low power consumption, is realized. An input signal amplitude is reduced every one half by a ladder network, and a transconductance amplifier stage is arranged corresponding to each node of the ladder network. An output of the transconductance amplifier stage is coupled to an output signal line in common. According to a control word WC , the transconductance amplifier stage is enabled selectively, and the output current which appears in the output signal line is added.
摘要:
The present invention provides a communication semiconductor integrated circuit device equipped with a high-frequency power amplifier circuit including a gain control amplifier and a bias circuit which supplies such a bias current as to linearly change the gain of the gain control amplifier, and a wireless communication system using the same. A bias current generating circuit which supplies a bias current to a linear amplifier that constitutes the communication high-frequency power amplifier circuit, comprises a plurality of variable current sources respectively different in current value and start level. These variable current sources are controlled according to an input control voltage and thereby combine their currents into a bias current. The combined bias current changes exponentially with respect to the input control voltage.