摘要:
An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing. The decision circuit receives the output of the automatic-gain-control amplifier and decides the binary nature of the voltage, and thus of the input optical signal.
摘要:
An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing. The decision circuit receives the output of the automatic-gain-control amplifier and decides the binary nature of the voltage, and thus of the input optical signal.
摘要:
A large time constant is caused due to parasitic capacitance at an anode terminal of a photodetector of an optical receiver. Therefore, an optical receiver wherein a variable negative capacitor mainly including an NPN-type transistor operable at high speed is configured and is connected to the input terminal of a preamplifier to which the output of the photodetector is input so that parasitic capacitance caused in the photodetector and due to packaging is equivalently reduced and the fluctuation of parasitic capacitance caused due to manufacturing dispersion is also compensated is provided.
摘要:
There is disclosed a variable-gain amplifier circuit that operates on a low voltage, exhibits low distortion, provides a wide range of variation, and is suitable for use in a low-power-consumption wireless communication system. The variable-gain amplifier circuit is configured so that a variable-load circuit, which includes three reactance function elements and provides a wide range of impedance variation, is connected to a conductor circuit whose output terminal generates a positive-phase output current proportional to conductance with respect to an input voltage.
摘要:
There is provided not only a radio frequency power amplifier using an SiGe HBT subject to a little amplification distortion, but also a communication system using the same. A conventional radio frequency power amplifier provides base bias paths of transistors Q1 through QN (SiGe HBT) with bias resistors R11 through R1N having resistance values three to five times higher than those of a ballast resistor attached to each transistor's base. A coil LB is provided in parallel with the bias resistor as a means for compensating a voltage drop due to direct current component IDC flowing through the bias resistor. Addition of the bias resistor suppresses non-linearity of low-frequency variations in an output current. Addition of the coil compensates for voltage drop. Accordingly, the maximum linear output power can be improved. As a result, it is possible to provide the power amplifier subject to a little amplification distortion within a wide output range.
摘要:
The present invention provides a semiconductor integrated circuit including an active mixer circuit that is operated at low voltage, low noise, and low power consumption. It includes a transconductance amplifier, a transformer, and a multiplier, connects a transformer between the transconductance amplifier and the multiplier, and separates between the transconductance amplifier and the multiplier with respect to direct current inside the transformer. Further, each of the tranconductance amplifier and the multiplier is configured of transistors that are single-stacked between the supply voltage terminal and ground terminal.
摘要:
There is disclosed a variable-gain amplifier circuit that operates on a low voltage, exhibits low distortion, provides a wide range of variation, and is suitable for use in a low-power-consumption wireless communication system. The variable-gain amplifier circuit is configured so that a variable-load circuit, which includes three reactance function elements and provides a wide range of impedance variation, is connected to a conductor circuit whose output terminal generates a positive-phase output current proportional to conductance with respect to an input voltage.
摘要:
The present invention provides a semiconductor integrated circuit including an active mixer circuit that is operated at low voltage, low noise, and low power consumption. It includes a transconductance amplifier, a transformer, and a multiplier, connects a transformer between the transconductance amplifier and the multiplier, and separates between the transconductance amplifier and the multiplier with respect to direct current inside the transformer. Further, each of the tranconductance amplifier and the multiplier is configured of transistors that are single-stacked between the supply voltage terminal and ground terminal.
摘要:
A bipolar transistor is provided in which both the base resistance and the base-collector capacitance are reduced and which is capable of operating at a high cutoff frequency. The semiconductor device is structured so that the emitter and extrinsic base are separated from each other by an insulator sidewall and the bottom faces of the insulator sidewall, and the emitter are approximately on the same plane. The extrinsic base electrode and the collector region are separated from each other by an insulator.
摘要:
A high-speed heterojunction bipolar transistor in a large injection of electrons from the emitter and a method for production thereof. In a typical example of the SiGeC heterojunction bipolar transistor, the collector has a layer of n-type single-crystal Si and a layer of n-type single-crystal SiGe, the base is a layer of heavily doped p-type single-crystal SiGeC, and the emitter is a layer of n-type single-crystal Si. At the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC, the bandgap of the p-type single-crystal SiGeC is larger than that of the layer of n-type single-crystal SiGe. Even though the effective neutral base expands due to an increase in electrons injected from the emitter, no energy barrier occurs in the conduction band at the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC. Thus, the diffusion of electrons is not inhibited and it is possible to realize high-speed heterojunction bipolar transistors even in the high injection state.