Owner's manual

AT86RF211

1942C–WIRE–06/02

Figure 16. LC Band-pass Filter

• 10 nF capacitors cut DC response forward and backward.

• The first network has the low cut-off frequency.

• The second network has the high cut-off frequency.

IF2 Amplifier Chain The input impedance of the IF2 amplifier is 1700Ω. This value enables the use of popu-

lar filters with impedance between 1500Ω and 2000Ω. It is directly connected to the FSK

demodulator. The bandwidth is internally limited to 1 MHz to minimize the noise before

the discriminator. It acts like a band pass filter centered at 455 kHz with capacitive cou-

pling between stages of amplifier and mixer. Total voltage gain is typically 86 dB.

Thanks to the capacitive coupling, no slow DC feedback loop is needed enabling a fast

turn on time. IF2DEC has to be decoupled with at least 2.2 nF.

Figure 17. Input of the IF2 Amplifier Schematic

10 nF

~ F1

~ F2

40 kHz or higher

global response

Filter

gain

Frequency

1900 Ω

IF2IN

IF2DEC