Analog evaluation circuit

Example of Analog Evaluation Circuit 6.2.3.1 General Description... 

This example shows an analog solution with a V/I converter. Another possibility is an instrumental amplifier instead of the V/I converter. The analog evaluation circuit is economical relating to wafer-area, but there are a lot of design features necessary for a high accurate signal evaluation. All circuit blocks must be designed to be insensitive to temperature and mechanical stress. 

Fig. 6.2.12 shows an example of a monolithic analog evaluation circuit with integrated diaphragm. The circuit blocks are made as described above. Typical parameters of the sensor are as follows. 

Such evaluation circuits can be analog or digital. One example of each type is described here. 

The Bosch microsilicon air-flow meter is available with analog (HFM5) or digital (HFM6) signal evaluation circuits. 

The method is quite effective, but is not widely used now because of the ubiquity of digital computers. Zuman and Patel - 36. show circuit designs for some kinetic schemes. Williams and Bruice made good use of the analog computer in their study of the reduction of pyruvate by 1,5-dihydroflavin. In this simulation eight rate constants were evaluated variations in these parameters of 5% yielded discemibly poorer curve fits. 

As stated in Sect. 6.4.1, it has been assumed that the measured experimental currents and converted charges when a potential Ep is applied can be considered as the sum of a pure faradaic contribution, given by Eqs. (6.130) and (6.131), and a non-faradaic one, /pnf and Qpnl. In order to evaluate the impact of these non-faradaic contributions on the total response, analytical expressions have been obtained. If it is assumed that initially the monolayer is at an open circuit potential, rest, and then a sequence of potential pulses , E2, -,Ep is applied, the expression for the non-faradaic charge Qp.nf can be deduced from the analogy between the solution-monolayer interface and an RC circuit [53] (shown in Fig. 6.24), so the following differential equation must be solved ... 

As we have seen in the preceding sections, the solution of unsteady conduction problems is, in general, not mathematically simple, and one must usually resort to a number of solution methods to evaluate the unsteady temperature distribution. We have also learned how to obtain solutions by using the available charts for a class of analytical results. In Chapter 4 we will explore the use of numerical computations to evaluate multidimensional and unsteady conduction problems. These computations require approximate difference formulations to represent time and spatial derivatives. Actually there exists a third and hybrid (analog) method that allows us to evaluate the temperature distribution in a conduction problem by using a timewise differential and spacewise difference formulation. This method utilizes electrical circuits to represent unsteady conduction problems. The circuits are selected in such a way that the voltages (representing temperatures) obey the same differential equations as the temperature. 

Although analog circuits that approximate 7(0 have been proposed (23), the function is usually evaluated by a numerical integration technique on a computer. Several different algorithms have been proposed for the evaluation (24, 25). The i-t data are usually divided into N equally spaced time intervals between / = 0 and t = tf, indexed by j then 7(0 becomes I k t), where At = tfIN and k varies between 0 and A, representing / = 0 and... 

The detector is protected from external noise by enclosing it within a grounded metallic box, and power is supplied via a local filter. Those circuits that are sensitive to electronic noise (mixers and preamplifiers) were isolated with the help of aluminum cases connected to the analog ground of the electronic assembly. The assembled selective microvoltmeter assembled detector was evaluated for its sensitivity, linearity, and pass bandwidth. This study was carried out with the help of a calibrated HF generator that was attached to a calibrated attenuator and so provided a sinusoidal voltage of amplitude 0.1-500 p,V and a frequency tunable between 0.5 and 8 MHz. 

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