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FREQUENCY PLAN

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26 / 325

275

285

295

305

315

325

335

345

355

365

375

385

0

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60

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80

IF1 (MHz)

TRF1121

TRF1221

SLWS170A – APRIL 2005 – REVISED DECEMBER 2005

The TRF1121/TRF1221 allow a variety of frequency plans. Figure 1 illustrates the allowable combinations of first

and second IFs. However, due to the fact that the chip features image reject mixers, significant changes in the

frequency plan can result in degradation of the image rejection as shown in Figure 2. LO leakage vs LO1

frequency is shown in Figure 3.

In order to maintain maximum image rejection and LO suppression, a recommended frequency plan is TxIF1 =

26 MHz, TxIF2 = 325 MHz.

Figure 1. Potential IF Combinations (TRF1121/1221)

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