FET amplifier

About: FET amplifier is a research topic. Over the lifetime, 7048 publications have been published within this topic receiving 77549 citations.

Improved VCSEL analog optical link

Abstract: An improved analog VCSEL optical link includes the following elements listed in their downstream order from the input to the output: an RF preamplifier (A1) for receiving a bandpass RF signal; a first impedance matching network (LASINT) to match the input impedance of a downstream VCSEL laser to the output impedance of the RF preamplifier (A1); the VCSEL laser coupled to one end of a multimode optical fibre of given length for transducing optically the electrical bandpass RF signal; a PIN diode coupled to the other end of the multimode optical fibre for transducing into electrical the optical signal coming from the fibre; a second impedance matching network (C2, L2) to match the output impedance of the PIN diode to the input impedance of a downstream low-noise transimpedance amplifier (T1) and minimise the noise figure of said transimpedance amplifier (T1) in the meanwhile; the transimpedance amplifier (T1) including a low-noise FET in common source configuration; an RF power amplifier (A2); an RF signal envelope detector generating a control signal for a variable phase shifter placed downstream the RF power amplifier (A2) to compensate for the AM/PM distortion introduced by both the optical fibre and the power amplifier itself; and, if necessary, a gain linearisation network of the RF power amplifier (A2) and/or the RF preamplifier (A1). The analog VCSEL optical link is suitable for the following uses: connecting indoor apparatuses with tower antennas either static, i.e. point-to-point radio relay, or directive arrays, i.e. point-to-multipoint systems; building-up a fibre infrastructure for connecting centralised base stations with respective pool of remote antennas serving as many cells of a cellular telephone system such as: PCS, GSM, UMTS, and similar; intra-building connections for distributing, CATV services (fig.4).

Transmitting-receiving circuit for radiocommunication apparatus, semiconductor integrated circuit device including the circuit, and radiocommunication apparatus including the same

Abstract: A changeover switch switches connection between an antenna and a transmitter amplifier and connection between the antenna and a receiver low noise amplifier, from one to the other. A first wire having characteristic impedance of 50 Ω connects the antenna and the changeover switch. A receiver matching circuit matches input impedance of the receiver low noise amplifier with the output impedance of the transmitter amplifier. An antenna side matching circuit matches the input impedance of the receiver low noise amplifier, which is matched with the output impedance of the transmitter amplifier by the receiver matching circuit, and the output impedance of the transmitter amplifier with the characteristic impedance of the first wire. The transmitter amplifier is connected with the changeover switch via a first coupling capacitance, and the receiver matching circuit is connected with the changeover switch via a second coupling capacitance.

Boost clock circuit for driving redundant wordlines and sample wordlines

Abstract: A boost clock signal generator which provides a boost clock signal from a pair of phase clocks. A pair of differentially-connected FET transistors which generate a boost clock signal. The transistors have drain connections connected to each of two clock signals, and commonly connected sources which form an output terminal for the boost clock signal. A series pass FET transistor is connected with each gate of the differential transistors for maintaining the gate at a floating voltage potential. A pair of capacitive elements couple the drain of each pair of differentially-connected FET transistors to the gate of an opposite transistor. A first and second logic circuit are connected to the series pass FET transistors for enabling one or the other of the differnetially-connected FET transistors into conduction. The pair of capacitive coupling elements coupling the drain of each pair of differentially-connected FET transistors to the gate of an opposite transistor increase switching speed of the clock signal generator.

Stacked linear power amplifier with capacitor feedback and resistor isolation

Abstract: A power amplifier with stacked, serially connected, field effect transistors is described. DC control voltage inputs are fed to the gates of each transistor. Capacitors are coupled to the transistors. The inputs and the capacitors are controlled to minimize generation of non-linearities of each field effect transistor and/or to maximize cancellation of distortions between the field effect transistors of the power amplifier in order to improve linearity of the power amplifier output.

Linear modulation using a linear and a non-linear amplifier

Abstract: A power amplifier uses a modulation technique that varies amplitude of a drive signal and, optionally, phase angle of the drive signal. The power amplifier comprises two coupled amplifiers, a first one of which is operated saturated to produce a constant voltage output. The first amplifier is coupled to a second one of the amplifiers via a quarteer wave transmission line. The second amplifier is operated in a linear mode to deliver an output signal controlled by an amplitude-modulating signal. The amplitude modulating signal may be a bipolar modulation signal that produces both positive and negative outputs from the second amplifier that add to or subtract from the output from the first amplifier to develop at a load inpedance net output signal amplitudes varying between a minimum or 'trough' amplitude and a maximum or 'crest' amplitude. The coupling of the first and second amplifiers through a quarter-wave line allows the signal current of the second amplifier to modulate the effective load impedance seen by the first amplifier to provide efficient amplifier coupling.