FET amplifier

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

Variable impedance load for a variable gain radio frequency amplifier

Abstract: A variable impedance load (104) is provided at the output of a radio frequency (RF) driver amplifier (102) having a variable gain. In an exemplary embodiment, the variable load (104) comprises a resistor (R) in series with a semiconductor device (M1). The semiconductor device (M1) has an impedance level determined by a drive current. The value of the drive current is related to the gain of the RF driver amplifier (102).

Solid-state image-pickup device with column-line amplifiers and limiter

Abstract: The levels of the power supply and the ground are kept constant against a parasitic resistance by keeping the constant current of an amplifier irrespective of the size of a pixel signal and the gain of the amplifier in this case in an image signal reading circuit system having the amplifier arranged to each column. The amplifier has a limiter at an output terminal thereof which limits an output voltage of the amplifier to a range for keeping the constant consumption-current.

Hybrid class amplifier

Abstract: A power amplifier (10) configured to generate impedances at harmonic frequencies such that the power amplifier (10) operates in a class C mode in a low output amplitude range and in a class F or inverse F mode in a high output amplitude range.

Rf power amplifier protection

Abstract: A circuit and method for protecting a radio frequency power amplifier against peak drain voltage. A detector circuit has an input connected to a drain of a power transistor of an amplification stage of the power amplifier to detect a peak drain voltage therefrom. The detector circuit outputs a protection signal when the detected peak drain voltage exceeds a predetermined reference level. A shutdown circuit is coupled to the detector circuit and inputs the protection signal therefrom. The protection signal is used to remove a gate bias of at least one amplification stage of the power amplifier. High frequency components are used in the detector and protection circuits to immediately reduce the drain voltage from one or more of the amplification stages.

Rail to rail operational transconductance amplifier

Abstract: A transconductance amplifier comprises two complementary differential amplifiers at the input (T1a,T2a; T1b,T2b), the quiescent currents of which are fixed by two current sources (Ia, Ib), respectively. The transconductance amplifier has a first operating range where the two differential amplifiers are active and second and third operating ranges where only one differential amplifier is active. Means (T3a,T4a,Iaa; T3b,T4b,Ibb) are provided for deriving a predetermined fraction of the currents provided by the current sources to the differential amplifiers, the means being respectively in one of the second or third ranges and the predetermined fraction being such that the transconductance of the active transistors in one of the second or third ranges is equal to twice the transconductance of the transistors in the first range.