STB5600 Просмотр технического описания (PDF) - STMicroelectronics

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STB5600

GPS RF FRONT-END IC

STMicroelectronics 

STB5600

A.1 Matching Network

The matching circuit may be a 50 Ohm / 300 Ohm balun transformer (figure 2), but a more economical

solution is a tuned match as shown below. A single 10nH inductor is optimal in cost, but may not meet

the users tolerance requirements over spreads of silicon and pcb material, as it has only around 1pF

tuning capacitance ( 2pF in series with 2pF inside the package).

Fig. 2 Matching Network with Balun

The first example (figure 3) increases the capacitance with a discrete capacitor, and uses a lower

inductance value. Both examples assume that the ceramic filter is dc blocking, both input to output, and

output to ground.

Fig. 3 Matching Network with two elements

The second (figure 4) example allows optimum matching by rationing the capacitors appropriately to

achieve voltage gain commensurate with the impedance translation. While it has a higher component

count, it is the version most tolerant of component variations and board capacitance.

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