FET amplifier

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

3-way doherty amplifier with minimum output network

Abstract: A 3-way Doherty amplifier has an amplifier input and an amplifier output. The amplifier has a main stage, a first peak stage and a second peak stage. The amplifier has an input network connecting the amplifier input to the inputs of the stages, and an output network connecting the stages to the amplifier output. The output network implements a phase shift of 90° between the output of the main stage and the amplifier output; a phase shift of 180° between the output of the first peak stage and the amplifier output; and a phase shift of 90° between the third output and the amplifier output.

Negative voltage generator

Abstract: An output voltage of a negative voltage generator contains a ripple because of a ripple occurring in a voltage produced by a charge pump circuit in the negative voltage generator. When the negative voltage is supplied to an FET amplifier, there arises a possibility that an unwanted spurious component occurs in an output of the FET amplifier. Since each of pair of circuits, that generate a negative voltage, are made mutually complementary, two charge pump circuits are used to cancel ripples. A ripple appearing in an output voltage can therefore be suppressed, and a negative voltage can eventually be supplied more stably. When the negative voltage generator is connected to, for example, an FET amplifier in order to supply a gate bias voltage to each FET in the FET amplifier, an unwanted spurious component that may be contained in an output of the FET amplifier can be removed.

Transimpedance amplifier for optical receivers

Abstract: An improved transimpedance amplifier allows an optical transmitter and receiver to be in close proximity to each other without fear of overloading the receiver. The improvement increases the dynamic range of the transimpedance amplifier and thereby the operating range of the receiver. A peak detector (22) at the output of an inverting amplifier (11) within the transimpedance amplifier turns on a field effect transistor (FET) circuit (23) when an AC component of an electrical signal becomes so large that the inverting amplifier would otherwise go into saturation. The FET circuit (23) acts as an AC shunt impedance at the input of the inverting amplifier and diverts the excess AC current to ground (30). Also, the FET circuit (23) acts as a DC resistance in concert with sense and sink current mirrors (21) and (24) to effectively divert an excessive DC component of the electrical signal away from the input of the inverting amplifier (11). Although the dynamic range of the transimpedance amplifier is increased, the optical sensitivity and the performance of the receiver remain unchanged.

Quaternary FET read only memory

Abstract: A quaternary FET read only memory is disclosed wherein each FET storage element in the array has its threshold adjusted by ion-implantation to one of four values. Each FET element in the array has its drain connected to a drain potential VDD. A binary input signal from a conventional binary, true/complement generator will then enable the gate of a selected FET storage cell and the output potential at the source of that selected storage cell will be VDD minus the customized threshold voltage of that storage cell, which is output at an output node. The signal on the output node is a quaternary signal which may be amplified by a quaternary sense amplifier circuit and then converted from quaternary to binary signal by means of a converter. The quaternary read only memory is capable of storing twice as much information per unit area as is a conventional FET binary read only memory. The concept may be expanded to N levels of information storage, using FET array devices with N different threshold voltages.

Amplifier for integrated laser/FLIR rangefinder

Abstract: An integrated laser/FLIR rangefinder has a laser energy detector generating an electrical signal in response to impinging laser energy, a preamplifier for amplifying the signal and a post amplifier for selectively shaping the signal output of the preamplifier. The preamplifier has a plurality of transistors connected in parallel provided for substantially reducing noise, a summing circuit sums the outputs of the plurality of transistors, and a trans-resistance amplifier produces a low impedance voltage difference output. The post amplifier includes a delay line and an operational amplifier having a positive terminal and a negative terminal. The positive terminal of the operational amplifier and a first end of the delay line are connected to the trans-resistance amplifier for delaying the output of the trans-resistance amplifier. A second end of the delay line is connected to the negative terminal of the operational amplifier. The operational amplifier combines the delayed and undelayed output of the trans-resistance amplifier and produces a spiked-type difference voltage signal. A low noise frequency compensation circuit allows detectors with what is normally considered inadequate bandwidth to be used to detect the laser return pulses and still produce a reasonably fast pulse with a low noise-level suitable for rangefinding.