| 摘要 |
In the context of matching a laser diode (154) with a laser driver IC (20), a microwave stub (166, 200, 202, 220, 222) is used in place of a conventional shunt resistor/capacitor network and takes advantage of radio frequency/microwave effects of electrical conductors on high frequency signals. The microwave stub (166, 200, 202, 220, 222) is a piece of microwave transmission line with a characteristic impedance defined by its physical dimensions and the PCB material of which it is made. With a transmission line having a characteristic of a distributed set of capacitors and inductors, the transmission line can be tuned to work over a range of frequencies by changing its operating length/width. A capacitor (168) is used to short circuit between the microwave stub (166, 200, 202, 220, 222) and ground (170b), with the position of the capacitor along the microwave stub (166, 200, 202, 220, 222) determining the operating length (and hence the frequency) of the microwave transmission line. According to the present invention, therefore, a matching network can be tuned simply by changing the position of the capacitor along the microwave stub (166, 200, 202, 220, 222) instead of having to have a number of different valued capacitors to hand.
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