TDK5111 Просмотр технического описания (PDF) - Infineon Technologies

Номер в каталоге

Компоненты Описание

производитель

TDK5111

ASK/FSK Transmitter 315 MHz

Infineon Technologies 

TDK 5111

Applications

As Figure 4-8 shows, detuning beyond the bandwidth of the matching circuit

results in a significant increase of collector current of the power amplifier and in

some loss of output power. This diagram shows the data for the circuit of the

test board at the frequency of 315 MHz. The effective load resistance of this

circuit is RL = 250 Ω, which is the optimum impedance for operation at 3 V. This

will lead to a dip of the collector current of approx. 10%.

18

16

14

12

10

8

6

4

2

0

285

300

315

330

345

360

375

fout [MHz]

Is [mA]

Pout [dBm]

Figure 4-8 Output power and collector current vs. frequency

pout_vs_frequ.wmf

C3, L2-C2 and C8 are the main matching components which are used to

transform the 50 Ω load at the SMA-RF-connector to a higher impedance at the

PA-output (250 Ω @ 3 V). L1 can be used for some finetuning of the resonant

frequency but should not become too small in order to keep its losses low.

The transformed impedance of 250+j0 Ω at the PA-output-pin can be verified

with a network analyzer using the following measurement procedure:

1. Calibrate your network analyzer.

2. Connect some short, low-loss 50 Ω cable to your network analyzer with an

open end on one side. Semirigid cable works best.

3. Use the „Port Extension“ feature of your network analyzer to shift the refer-

ence plane of your network analyzer to the open end of the cable.

4. Connect the center-conductor of the cable to the solder pad of the pin „PA“

of the IC. The outer conductor has to be grounded. Very short connections

have to be used. Do not remove the IC or any part of the matching-compo-

nents!

5. Screw a 50 Ω dummy-load on the RF-I/O-SMA-connector

6. Be sure that your network analyzer is AC-coupled and turn on the power

supply of the IC. The TDK5111 has to be in PLL-Enable-Mode.

7. Measure the S-parameter S11

Wireless Components

4 - 11

Specification, October 2002

Share Link: