Topic
Operational transconductance amplifier
About: Operational transconductance amplifier is a research topic. Over the lifetime, 14358 publications have been published within this topic receiving 158733 citations.
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Patent•
24 Aug 1999
TL;DR: In this article, a linear function processor generates linear function correction signals which are linear functions of previous samples of the input signal in order to compensate for distortion effects of the amplifier related to the history of input signal.
Abstract: An amplifier arrangement comprising an amplifier for amplifying an input radio frequency (RF) signal to generate an output RF signal. A linear function processor generates a linear function correction signal which is a linear function of previous samples of the input signal in order to compensate for distortion effects of the amplifier related to the history of the input signal. A non-linear function processor generates a non-linear function of the input signal in order to compensate for instantaneous distortion effects of the amplifier. Then a pre-distortion processor distorts the current input signal in accordance with the linear and non-linear function correction signals in order to compensate for both types of distortion in the output signal.
219 citations
TL;DR: In this paper, a monolithic GaAs traveling-wave amplifier with 9dB gain and + 1-dB gain flatness in the 1-13 GHz frequency range is described, which is realized in monolithic form on a 0.1mm GaAs substrate with 50-Omega input and output lines.
Abstract: This paper describes a monolithic GaAs traveling-wave amplifier with 9-dB gain and +-1-dB gain flatness in the 1-13-GHz frequency range. The circuit is realized in monolithic form on a 0.1-mm GaAs substrate with 50-Omega input and output lines. In this approach GaAs FET's periodically load input and output microstrip lines and provide the coupling between them with proper phase through their transconductance. Experimental results and the circuit details of such a structure are discussed. Initial results of a noise analysis and predictions on the noise performance are also given.
212 citations
TL;DR: In this article, the authors derived the high-frequency nonlinear behavior of the common-emitter and differential-pair transconductance stages with inductive degeneration and showed that transconductances stages using inductive degradations are more linear than those using capacitive or resistive degenerations.
Abstract: Equations describing the high-frequency nonlinear behavior of common-emitter and differential-pair transconductance stages are derived. The equations show that transconductance stages using inductive degeneration are more linear than those using capacitive or resistive degeneration, and that the common-emitter transconductance stages are more linear than the differential-pair transconductance stages with the same bias current and transconductance. The nonlinearity equations can also be used to explain the class AB behavior of the common-emitter transconductance stage with inductive degeneration.
211 citations
TL;DR: This paper describes the design and performance of a 90 nm CMOS SAW-less receiver with DigRF interface that supports 10 WCDMA bands and 4 GSM bands and results in current drain and die area savings as well as improved noise.
Abstract: This paper describes the design and performance of a 90 nm CMOS SAW-less receiver with DigRF interface that supports 10 WCDMA bands (I, II, III, IV, V, VI, VIII, IX, X, XI) and 4 GSM bands (GSM850, EGSM900, DCS1800, PCS1900). The receiver is part of a single-chip SAW-less transceiver reference platform IC for mass-market smartphones, which has been designed to meet Category 10 HSDPA (High Speed Downlink Packet Access) requirements. The novel receiver core consists of a single-stage transconductance amplifier (TCA) with large gain control range, a current commutating passive mixer enhanced for automatic on chip IIP2 calibration with 25% duty-cycle LO injection and threshold adjust, and current-input complex Direct Coupled Filter (DCF). The low noise TCAs are designed without inductive loads to save area. A self-contained on chip automatic IIP2 calibration system with algorithm routine, implemented in firmware, is used to optimize IIP2 performance. This topology eliminates the external LNA, inter-stage SAW filter and transimpedance amplifier (TZA) in conventional WCDMA designs and results in current drain and die area savings as well as improved noise. The 25% duty-cycle LO injection, with threshold adjustment, into a current driven passive double-balanced mixer results in 3 dB additional gain, lower noise figure and lower intermodulation distortion. Large signal blocking and 1/f noise performance are improved significantly by eliminating the 0 and 180deg LO signal crossover at the mixer. The full receiver achieves 2.2 dB/2.39 dB simplex/duplex NF (with - 24.5 dBm TX leakage), > 90 dBm complex two-tone IIP2, 60 dB gain and - 1/+ 5 dBm half/full-duplex image IIP3. The receiver core consumes only 15.1 mA from a 1.5 V supply.
210 citations
Patent•
29 Jun 1979
TL;DR: In this article, a method and apparatus for monitoring and obtaining actual bio-electrical characteristics of a subject, such as EEG, or determinants of the psycho-electro-physiological state of the subject, under predetermined conditions of evoked response stimuli, and by interaction with a computer, apply cutaneous electrical stimulation to the subject using a signal generator to modify current amplitude and frequency in a direction to achieve bioelectrical characteristic in the subject related to the actual bio electrical characteristics monitored.
Abstract: A method and apparatus for monitoring and obtaining actual bio-electrical characteristics of a subject, such as EEG, or determinants of the psycho-electro-physiological state of the subject, under predetermined conditions of evoked response stimuli, and by interaction with a computer, apply cutaneous electrical stimulation to the subject, using a signal generator to modify current amplitude and frequency in a direction to achieve bio-electrical characteristics in the subject related to the actual bio-electrical characteristics monitored. The signal generator may have an output of several frequencies simultaneously, and uses a sinusoidal waveform output, with battery power passed through a transformer to power a transconductance amplifier to obtain constant current output despite resistance changes in the line with the subject, and with the transformer not placed in the signal path of the sinusoidal waveform.
203 citations