Telecommunication Electronics – Phase Locked Loop in Lock Down with Geoff Varrall

We at Artech House encourage a spirit of collaboration, and we couldn’t be more thrilled to have author Geoff Varrall review Telecommunication Electronics, by Dante Del Corso, Roberto Quaglia, Vittorio Camarchia, Paolo Bardella. Read on for his insights:

Those of us still self-isolating have a once in a lifetime (hopefully longer) opportunity to catch up on some of those engineering topics that either we always wanted to know about or knew a lot about once but have now forgotten.

For twenty years I sat through technical workshops in which my co-director Roger Belcher took young and not so young engineers on a magical mystery tour of the phase locked loop, that Swiss army knife of electronic circuit design.

My lesser role was to put an economic price/economic benefit value to good practice in mobile phone and then Smart Phone design.

Essentially one dB of performance gain in the front end design of a cell phone translated directly to a 10% gain in network density for an equivalent network loading.

In this new title from Artech House, written by four engineers with huge analogue and digital design experience, we are taken on a journey around the intimate system design considerations of a mobile phone.

The book is not just about the phase locked loop but covers each of the RF sub systems in a typical RF Front End (RFFE) and the processes used to move analogue signals to and from digital baseband. It is a story of the art of elegant compromise.

Chapter 1 reviews radio system architectures and their role in detecting and demodulating radio signals of the order of a few microvolts in the presence of transmitted signals of the order of hundreds of millivolts, reminding us of the benefits and drawbacks of the Superhet and relative advantages and disadvantages of Zero IF and direct conversion options.

Band pass and low pass filtering is addressed together with ADC and DAC system design considerations and performance trade-offs across a range of signal bandwidths, carrier frequencies and modulation options.

Chapter 2 addresses transmitter RF power amplifiers and related noise, linearity, efficiency and dynamic range considerations and related issues of non-linearity and unwanted harmonics and distortion. There is a reminder about transistor behavioural modelling, testing and behavioural observation methodologies and the use of dynamic nonlinear models to design power amplifiers, oscillators and mixers and to determine the DC bias point of the transistor.

Conditions of conditional and unconditional stability are discussed together with the need to comprehend parasitic effects when the dimensions of the transistor are non-negligible compared with the wavelength.

Chapter 3 covers frequency conversion circuits, passive and active mixers and mixer architectures including single and double balanced mixers and harmonic or sub harmonic mixers for millimetre wave radios and diode mixers and doublers.

Chapter 4 reviews how phase locked loops are used to generate, synchronise and demodulate signals in the analogue and digital domain including the implementation of phase detection, voltage controlled oscillators and low pass filters, signal processing, demodulation, timing recovery, frequency synthesisers and DDS.  The use of the PLL to compensate tolerance and drift in oscillators is discussed and the ways in which a PLL can be used to remove wideband noise, distortion and unwanted signal modulation

Chapter 5 dives into analogue to digital and digital to analogue conversion and sampling theory, reminding us why the bandwidth of the signal rather than the carrier frequency is the dominant determinant of efficiency. Techniques of over and under sampling are addressed together with the performance trade-offs implicit in jitter error, quantization error, quantisation noise power and aliasing and how performance of the complete A to D system can be described in terms of ENOB (effective number of bits), spurious free dynamic range and total harmonic distortion

The book is targeted at designers of telecommunication equipment at system and circuit level but will be useful to any and or all of us presently addressing the front end performance design challenges implicit in moving into the millimetre band.

For more information on Telecommunication Electronics or to order, click here.

To order Geoff Varrall’s books, click here.

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