Control óptico de un oscilador MMIC en banda Ku

This paper shows the latest results research on the optical control of a GaAs chip monolithic Voltage Controlled Oscillator, and is an extension of previous work realized by our group in the field of opticalmicrowave interaction. The oscillator was originally designed for the transmitter stage of a VSAT communications front-end system in the 14.5 GHz band. The possibilities of optical control of the VCO by illumination of the PHEMT transistor are demonstrated through measurements of the oscillation output power and frequency. An optical control range of 8dB of oscillation output power and up to 400MHz of oscillation frequency has been obtained

Control óptico de un amplificador MMIC de AsGa en banda S

This paper shows the results of research on the optical control of a GaAs chip monolithic amplifier, and is an extension of previous work by our group in the field of optical-microwave interaction . The amplifier was originally for the transmitter stage of an indoor mobile communications system in the 2.4 GHz band. The possibilities of optical control of this amplifier are evidenced as follows: if the amplifier operates with the same biasing, the gain can be optically controlled from a condition of almost isolation, (gain less than - 5 dB), up to an active condition, (gain greater than 10 dB), which gives a range of optical control of about 15 dB. At the same time, the optical control provides an improvement of the input and output matching in a range of 12dB and 6dB, respectively. This optical control promises an interesting control of gain and matching for other microwave FET based active devices

Modelo de gran-señal para transistores P-HEMT y MESFET de microondas incluyendo efectos ópticos

As an extension of our previous works in the opticalmicrowave interaction field, this paper shows the result of the research on large signal dynamic behavior (pulsed I/V curves) of AlGaAs P-HEMT (pseudomorphic high electron mobility transistor) devices, in the overall I/V plane, when the incident optical input power is changed. A complete bias and optical power dependent of the large signal model for a P-HEMT is determined from experimental scattering parameters, DC and pulsed measurements. All derivatives of the model shown here are continuous for a realistic description of circuit distortion and intermodulation. Experimental results show very good agreement with the theoretical analysis

Propiedades dinámicas gran-señal de un transistor MESFET de GaAs bajo iluminación óptica

This paper is the result of an extensive investigation on the large signal dynamic behaviour (Pulsed I/V) of unipolar GaAs device, in the overall i/V plane, when varying the incident optical power. We have observed a hyperbolic dependence with the gate voltage along with a quasi-logarithmic dependence in front of the optical power

Control óptico de dispositivos microondas

The distinct advantages of optical transmission systems and the increasing use of microwave frequencies within general communication systems, coupled with the ability to integrate microwave and optical components onto a single slice of GaAs have stimulated considerable interest in the development of microwave optoelectronic systems. The optical circuits are advantageous because they can be integrated into the microwave circuits without interfering with them, they have low losses and small dimensions, short reaction time and wide band. This papers present the DC characteristics of a MESFET under different conditions of illumination and different resistances in the gate terminal

MESFET GaAs controlado fotónicamente

The illumination characteristic of GaAs MESFET has been measured with single optical fiber is reported. This technique permits an optical control and observer the edge-effect in the MESFET planar. Application in high speed device is proposed

Nuevo modelo de capacidad de puerta para transistores MESFET de microondas incluyendo efectos ópticos

A new set of pseudo-empirical equations are presented in order to simulate the optical and bias dependencies of GaAs MESFET junction capacitances, which is valid for the whole I-V plane. The variations induced in the small signal equivalent circuit by the optical illumination are extracted from on-wafer scattering parameter measurements. New linear and quasi-logarithmic variations versus the incident optical power are shown for gate-to-drain and gate-to-source (Cgd and Cgs) capacitances. Furthermore, experimental results are in very good agreement with the simulated values for a wide range of optical power and bias conditions

Interacción óptica-microondas: variación de la característica y extracción de los parámetros del círculo equivalente del MESFET bajo los efectos de la iluminación

In this paper we discuss the different effect contributions on MESFET characteristics under ilumination. The experimental results confirm the validity of the theoretical predictions. The illumination influence over the small signal equivalent circuit parameters is also analized for different optical powers. This interaction give us the possibility of using the optical signals to control the MESFET behavior

Nuevo modelo de gran-señal para transistores MESFET de microondas incluyendo efectos ópticos

This paper is the result of our research on large signal dynamic behavior (Pulsed I/V curves) of GaAs device, in the overall I/V plane, when the incident optical input power is changed. Acomplete bias and optical power dependent large signal model for a MESFET is determined from experimental S-parameters, DC and pulsed measurements. All derivatives of the model shown here are continuous for a realistic description of circuit distortion and intermodulation. The dependencies of circuit elements with optical illumination and the quiescent operating point are evaluated, and a comparison between theoretical and measured results over optical power and bias ranges is shown. Experimental results show a very good agreement with the theoretical analysis

Efecto de borde en el transistor MESFET GaAs bajo iluminación óptica

A photovoltaic gate edge effect in planar GaAs MESFET’s has been developmented whereby a sharp increase in optical gain at the transistor edges occurs, is reported in this document. This optical effect is obtained when the transistor edges are illuminated and enchances the fotosensivity of these devices when they are used as photodetectors