Multiplier Circuits

As more and more electrical designs utilize the benefits in performance, cost, and size of ICs, demand for DC power in systems has been increasing. 

Unfortunately, sometimes the only power input available for these circuits is an AC waveform, with a spare winding from a transformer that must power the housekeeping supplies of the system. 

Adding a DC housekeeping supply adds cost and complexity, often a simpler and less expensive solution is to use a voltage multiplier circuit. 

Using these circuits requires fewer parts and provides a reasonable design alternative when circumstances permit their use. The information in this chapter will aid the designer in predicting the performance of these circuits and maximizing their capability and usefulness in the system. 

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The detector of mosf insfruments consisfs of a counter that produces a current proportional to the number of ions that strike it. Electron multiplier circuits allow accurate measurement of fhe current from even a single ion sfriking the detector. The signal from the detector is fed to a recorder, which produces fhe actual mass spectrum. 

A photomultiplier circuit using a 1P28 tube designed for variable rise times between 1 ys and 40 ns is shown in Fig. 9 (15). The amplification of this photomultiplier is adapted for a xenon arc lamp, which is not pulsed (CW). Other multiplier circuits with different rise times and different light sensitivity are found in the literature (13). 

Through the use of electron multiplier circuits, this current can be measured so accurately that the current caused by just one ion striking the detector can be measured. These detectors are based on the simple concept of the Earaday cup, a metal cup that is in the path of ions emanating from the mass analyzer. When an ion strikes the surface of the electron multiplier two electrons are ejected. The approximately 2-kV potential difference between the opening and end of the detector... 

To understand how this over-response can occur at high output currents, consider the currents flowing through each of the elements of the multiplier circuit shown in Figure 3.8(a). 

Figure 10.41. Voltage multiplier circuit with 4X multiplication factor.

Programs to solve AC voltage multiplier circuit require"odeiv"... 

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