Oscillator-amplifier design

We have selected a broad cross section of analog and mixed-mode designs, which we have simulated, as well as constructed. The circuits are grouped into logical chapters. Generic topics, such as oscillators, amplifiers/receivers, power converters, and filters, all head their own chapter. Each chapter starts with a brief overview of the function of the circuits in the chapter. This is followed by several circuit examples. For instance, in the chapter on reference circuits, the beginning details what reference circuits are and their uses at the system level. This is followed by a detailed discussion on a single type of reference circuit, the band gap reference. 

Fig. 2. A typical pulsed, tunable dye laser, of the Hansch design, in an oscillator— amplifier configuration. Suitable pump lasers are Nj, excimer and Nd YAG-harmonics. The broken line represents a pressure chamber which is required to scan the wavelength if an air spaced Fabry—Perot etalon is used. With solid etalons, tuning is achieved by tilting the etalon and the pressure chamber is not required.

The equipment consists of a feed system, the reactor section, a GC, and an MS for product analysis. A Rupprecht and Patashnick TEOM 1500 PMA (Pulse Mass Analyzer) was used in the experimental design shown in Fig. 2. The tapered element with the catalyst bed on its end oscillates in a clamped-free mode. This is accomplished through a sensitive feedback amplifier control circuit connected to a mechanical drive to supply the necessary energy. The reactor tube is constructed of proprietary glass ( engineered glass ) (5). The reactor material has proved to be sufficiently inert for a number of applications. The catalyst bed is held in place by quartz, a-alumina, or carbon wool, depending on the conditions, and a metal cap. 

Use of field effect transistor (FET) amplifiers for two purposes amplification of the oscillator output to one or more watts, and also for amplification of the ESR microwave signal using a very low noise FET. Care must be taken in protection of detector diodes, in design of switches to introduce the amplifiers into the circuit, and in maintaining good operator discipline in use of the bridge. 

Current feedback amplifiers always consist of a diamond transistor (DT) and a buffer stage internally connected. The OPA660 [42] or its replacement OPA860 [43] allows separated access to both circuit parts so that a voltage-controlled current source (OTA) at a bandwidth of 90 MHz and a buffer stage at a bandwidth of 700 MHz are available. In contrast to normal transistors the diamond transistor, whose temperature-stabile operating point is internally determined, allows four-quadrant operation. The OTA provides the required almost-ideal transistor to design an emitter-coupled oscillator. 

For designing an ALC, a precision rectifier, a comparafor, a proportional-integral (PI) confroller, and a gain-confrollable amplifier are required. The block diagram of fhe quartz crystal oscillator with ALC is depicted in Fig. 21... 

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