The design of electronic amplifiers in microwave photonic links requires analog circuit design techniques for the lower part of the microwave spectrum but also microwave techniques above a few gigahertz. These steps give rise to numerous processes that are not discussed here. The appendix, section 7.4, outlines the different parameters used in circuit design and this Chapter discusses the paths and trends in the design of these circuits. It should be noted that numerous technologies are used for high-frequency circuits, e.g. Si CMOS technologies, bipolar Si/SiGe technologies or HFET, or HBT technologies on GaAs or on InP substrates. These technologies have been synthesized in [SCA 09], but the technologies are integrated in the form of monolithic microwave integrated circuit (MMIC) chips.
7.2.1. Different roles of electronic amplifiers on optical emitter
At a microwave photonic link input, there is an electronic amplifier performing several functions.
If the modulation signal is directly introduced on the laser biasing, the amplifier has a double function: it serves as an impedance matching between the 50 Ω of the microwave source and the few ohms of the laser input impedance and must also supply a non-negligible current to the laser input. For low frequencies, this matching is realized by a classical analog circuit and for frequencies ...