Abstract
A Square Law Device may be considered as being
any circuit or arrangement of components, capable of producing
an output proportional to the mathematical square of the input.
These devices may be electrical, mechanical, hydraulic or any
combination of these. The thesis is confined to electrical
square law devices, which are by far the most numerous. The
input and output quantities are usually represented as voltages or
currents.
A literature survey was conducted and a large number
of different types of square law devices were revealed. These
have been classified into sections, depending on the mode of
squaring, and each has been examined for various properties.
Some devices have been examined theoretically, and others by
actually developing and constructing a circuit and taking a series
of measurements, in each case a conclusion is drawn concerning
the accuracy, frequency response and dynamic range.
This classification and examination of square law devices
showed that, although there were many devices excelling in one
property, there were very few having excellent all round
performance. Either a method for improving the performance
of existing devices or a completely new device with excellent all
round properties would be needed to improve the position, it was
decided to attempt to develop a method to improve the properties
of existing devices, and the last and major section of the thesis
is devoted to the treatment of a method for reducing distortion
due to odd powers in the nominal square law transfer function.
A large fundamental co-efficient is one of the most common forms
of distortion in these devices.
The thoughts leading to the method of improvement
are given, with an analysis proving the mathematical possibility.
A square law device was constructed using the method and
rigorous tests carried out to compare the performance of the
device on its own, with that when it is incorporated in the circuit
for improving the distortion. The thesis shows that a large
improvement in both the accuracy and dynamic range is possible.