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).

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.

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.

Fig. 2 Matching Network with Balun

Fig. 3 Matching Network with two elements

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