BOOK_CONTENT
From Design and Development of Medical Electronic Instrumentation

As they operate, digital circuits constantly switch the state of lines between a high-voltage
level and a low-voltage level to represent binary states. As shown in Figure 4.1a, the resulting
time-domain waveform on any single line of a digital circuit can thus be idealized as
a train of trapezoidal pulses of amplitude (either current I or voltage V) A, rise time tr, fall
time tf(between 10 and 90% of the amplitude), pulse width τ (at 50% of the amplitude),
and period T.

The Fourier envelope of all frequency-domain components generated by such a periodic
pulse train can be approximated by the nomogram of Figure 4.1b. The frequency spectrum
is composed mainly of a series of discrete sine-wave harmonics starting at the fundamental
frequency f0 = 1/T and continuing for all integer multiples of f0. The nomogram
identifies two frequencies of interest. The first is f1, above which the locus of the maximum
amplitudes rolls off with a 1/f slope. The second, f2, is the limit above which the locus rolls
off at a more abrupt rate of 1/f2...


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Products & Services
Signal Generators
Signal generators and waveform generators are used to test and align all types of transmitters and receivers, to measure frequency and to generate a signal, waveform or noise source. Signal generators can use AC energy, audio frequency (AF) and radio frequency (RF) to function.
Spectrum Analyzers and Signal Analyzers
Spectrum analyzers and signal analyzers display raw, unprocessed signal information such as voltage, power, period, wave shape, sidebands, and frequency. They can provide the user with a clear and precise window into the frequency spectrum.
Isolation Amplifiers
Isolation amplifiers electrically isolate input and output signals, often by inductive couplings. Isolation amplifiers, or iso-amps as they are sometimes called, may be used to protect components from potentially dangerous voltages or to amplify low-level analog signals in applications with multiple channels.
Medical Equipment and Supplies
Medical equipment and supplies are used in medical, dental, hospital, pharmacy, and clinical laboratories.

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