tailieunhanh - Nguyên tắc cơ bản của thiết kế mạch RF với tiếng ồn thấp dao động P7

Modern large signal modelling packages offer extremely accurate results if good models are provided. However, they are often slow when optimisation is required. It would therefore be very useful to be able to optimise the performance of a circuit, such as the load network for a power amplifier, by being able to vary the important parameter values as well as the frequency and then to observe the waveforms on an ‘oscilloscope-like’ display in real time. | Fundamentals of RF Circuit Design with Low Noise Oscillators. Jeremy Everard Copyright 2001 John Wiley Sons Ltd ISBNs 0-471-49793-2 Hardback 0-470-84175-3 Electronic 7 Real Time Large Signal Modelling Introduction Modern large signal modelling packages offer extremely accurate results if good models are provided. However they are often slow when optimisation is required. It would therefore be very useful to be able to optimise the performance of a circuit such as the load network for a power amplifier by being able to vary the important parameter values as well as the frequency and then to observe the waveforms on an oscilloscope-like display in real time. This chapter describes a circuit simulator which uses the mouse with crosshatch and slider controls to vary the component values and frequency at the same time as solving the relevant differential equations. The techniques for entering the differential equations for the circuit are described. These differential equations are computed in difference form and are calculated sequentially and repetitively while the component values and frequency are varied. This is similar to most commercial time domain simulators but it is shown here that it is relatively easy to write down the equations for fairly simple circuits. This also provides insight into the operation of large signal simulators. The simulator was originally written in QuickBasic for an Apple Macintosh computer as this included full mouse functionality. The version presented here uses Visual Basic Version 6 for a PC and enables the data to be presented in an easily readable format. A version of this program is used here to examine the response of a broadband highly efficient amplifier load network operating around 1-2GHz. Real Time Large signal modelling 275 Simulator A typical simulator layout is shown in Figure . It consists of a main form entitled Form 1 which displays four waveforms and in this case always shows five cycles independent of .