Multifunction GaAs MMIC transmitter/receiver for onboard satellite equipment
This paper describes the development of a new GaAs MMIC to be used in transmit/receive modules for S band transponders. The IC, which includes five different functions, reduces the sue of the system whilst maintaining and even improving system performance. Amplification, phase shifting, and mixing are some of the functions integrated in the same chip. The goal of the work is to reduce the number, size, and consequently, the cost of the circuitry currently in use through an European commercial Enhancement/Depletion (E/D) pHEMT process, compatible with low noise reception. A maximum conversion gain more than 54 dB has been achieved with a gain control more than 27 dB. A 0 dBm output power at 1dB compression point (P1dB) has been measured when a CW stimulus was used as input signal, while more than 35 dB of Adjacent Channel Power Ratio (ACPR) was tested for a BPSK input signal.
Dual band monolithic AGC amplifier for space applications based on a commercial 0.2 /spl mu/m PHEMT technology
This paper reports the design and measurement of a dual band monolithic AGC amplifier to be used in transmit/receive modules for Telemetry, Tracking and Control (TTC) of satellite systems. The amplifier is also included in a multifunction Monolithic Microwave Integrated Circuit, MMIC, containing frequency converters. The block diagram of this chip is shown. The goal of the work is to reduce the number, size, and consequently, the cost of the circuitry actually in use, whilst maintaining performance, through the use of mature GaAs PHEMT technology. Issues such as circuit topologies, dc power consumption, circuit area minimization and optimization are all important factors that are addressed during the design.
A technique for large-field, superficial electron therapy.
The application of electron beams to radiation therapy has received increased attention in recent years. This interest stems largely from the special characteristics of the electron depth-dose distribution; the fall-off in depth dose near the end of the range of the electrons is particularly rapid for electron beams having energies less than about 10 Mev. Such an electron beam is suitable for the treatment of widespread, superficial lesions, where it is desirable to minimize the dose to deep tissues. All the common sources of super-voltage x-rays, apart from radioactive substances, are inherently capable of producing an external beam of electrons, though with varying degrees of complexity. Electrons of about the energy suitable for superficial therapy (several Mev) may be used to produce an x-ray beam which is sufficiently penetrating for the treatment of even the deepest lesions. The Stanford medical linear accelerator was designed to provide both x-rays and electron beams. The accelerator and its applic...