FET amplifier

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

Circuit for measuring low capacitances

Abstract: A capacitance to be measured is connected between the input and output of an inverting amplifier. A bistable circuit has an input connected to the output of the inverting amplifier and an output impedance inversely proportional to the capacitance to be measured. A resistive feedback is connected from the output of the bistable circuit to the input of the inverting amplifier.

A Broadband Reconfigurable Load Modulated Balanced Amplifier (LMBA)

Abstract: The Load Modulated Balanced Amplifier (LMBA) uses a control signal (CSP), injected to the normally terminated port at the output coupler of a balanced amplifier (BA), to modulate the BA transistor's impedance. The hybrid circuit demonstrator described here uses metal-backed multilayer organic substrate and GaN discrete devices. Maximum output power levels above 39.5 dBm are achieved at around P3dB. DE above 60% is seen between 4.5 and 7.5 GHz for power back-off to 7 dB with a fixed CSP of 1 W, and the bias between 18 to 28 V.

Low-noise amplifier

Abstract: Methods and corresponding systems in a low noise amplifier include selecting a selected sub-band for amplifying, wherein the selected sub-band is one of a plurality of sub-bands, wherein each sub-band is a portion of a frequency band, and wherein each sub-band has a corresponding sub-band center frequency. Next, a gate-source capacitor is adjusted so that a real part of an LNA input impedance corresponds to a real part of a source impedance at the selected sub-band center frequency. A match capacitor is also adjusted so that the LNA input impedance corresponds to the complex conjugate of the source impedance at the selected sub-band center frequency. The gate-source capacitor and the match capacitor can each be adjusted by recalling capacitor values from memory that correspond to the selected sub-band, and connecting selected capacitor components in response to the recalled capacitor values.

A method and a device for adjusting power amplifier properties

Abstract: A method and a device for tuning power amplifier (PA, 203) properties such as back-off. A peak-to-average value (PAR) of the amplifier input signal is first obtained by control means (206) and then used for adjusting the power amplifier (203) with tuning means (204, 208, 210) functionally connected to the amplifier (203). The suggested solution is advantageously exploited in a wireless communications device like a mobile terminal to optimize the performance thereof by, for example, reducing the power dissipation in the transmitter.

A novel Doherty amplifier for enhanced load modulation and higher bandwidth

Abstract: We are reporting a new topology for the Doherty amplifier to increase its bandwidth and enhance the load modulation. A varactor-based impedance transformer has been employed to replace the bulky and narrowband quarter-wave impedance inverter. Load modulation is carried out adaptively using the proposed varactor-based structure based on the input power level. An envelope detector is employed for adaptive impedance transformation of the carrier amplifier as well as bias adaptation of the peak amplifier. Based on the proposed topology, a 2W Doherty amplifier has been fabricated using discrete pHEMT transistors and low loss varactors. In order to evaluate the broad-band/multi-band performance of the proposed topology, measurements have been carried out at three sample frequencies (1.8GHZ, 2GHz and 2.2GHz) over a 400 MHz bandwidth. Power added efficiency of better than 45.3% has been achieved at maximum power level and 6-dB power back-off and maintained over the entire bandwidth. Measured IM3 is better than −42.2dBc at P1dB of 33dBm for all design frequencies.