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TAMPERE UNIVERSITY OF TECHNOLOGY TLT-8207 Communication Circuits and Modules - 1
Department of Electronics and Communications Jani Järvenhaara

 

Stekanus. wirdatmadja E ut. fr
Exam - 14.3.2013

You may not use any notes, but use of your own calculator is allowed.
Each guestion is worth six (6) points.

1. Explain BRIEFLY the following terms or perform the tasks:
- Cascade connection of amplifiers.
- Inverting and non-inverting amplifier.
- Ideal voltage amplifier model.
- Draw the circuit symbol of npn BJT and mark the directions of the currents and the
polarities of the voltages, when BJT is in active region.
- In which region of operation the NMOS transistor can be used as a controllable resistor?
- Power added efficiency (PAE) in power amplifiers.

2. Draw the circuit sehematic and explain the operation of Common Collector amplifier.

3. (a) In Figure 1 is shown a basic Common Gate LNA. How it should be modified to
obtain LNA with gain step? Draw the schematic and explain how the gain step is
achieved. (b) Which LNA configuration, Common Base or Common Emitter, couples
more signal (backward) to the antenna?

 

Figure 1. Basic CG LNA.

4. Draw a block diagram of a simple phase locked loop (with low pass filter) and
explain its operation. Support your explanation with waveforms.

5. (a) Which type of power amplifier is shown in the Figure 2? Explain the operation
principle of this power amplifier. What is the ideal maximum drain efficiency this PA
could achieve? (b) Compare the PA in Figure 2 with at least two other PAs in terms
of efficiency. Explain briefly why the efficiency is higher or lower in other PAs?

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Figure 2. Some power amplifier.