Datasheet

LPF
MCU
PGA
PA
1
2 f 22 kp W´ ´ ´
C =
See Note 2
Inside the AFE030
Tx_F_OUT
Tx_PGA_
IN
Tx_F_IN1
PA_OUT1
PA_OUT2
Tx_PGA_
OUT
Tx_F_IN2
PA_IN
C
GPIO
GPIO
See Note 1
43 kW
43 kW
C
LPF
MCU
PGA
PA
1
2 f 22 kp W´ ´ ´
C =
See Note 3
Tx_F_OUT
Tx_PGA_
IN
Tx_F_IN1
PA_OUT1
PA_OUT2
Tx_PGA_
OUT
Tx_F_IN2
PA_IN
C
C
GPIO
See Note 1
Inside the AFE030
510 W 510 W
See Note 2
AFE030
www.ti.com SBOS588A –DECEMBER 2011– REVISED DECEMBER 2011
(1) When using both Tx Filter inputs, use 43-kΩ resistors to match the input resistance for best frequency response.
(2) For capacitor value C, f is the desired lower cutoff frequency and 22 kΩ is the PA input resistance.
Figure 29. Recommended Tx Signal Chain Connections in PWM Mode Using Two PWM Signals
In PWM mode, there is inherently more distortion from the PWM signal than from the internal DAC. To achieve
the best results in PWM mode, add passive RC filters to increase the low-pass filtering. Figure 30 and Figure 31
illustrate the recommended locations of these RC filters.
(1) Leave unused Tx Filter input unconnected.
(2) Refer to Table 2.
(3) For capacitor value C, f is the desired lower cutoff frequency and 22 kΩ is the PA input resistance.
Figure 30. Recommended Tx Signal Chain Connections in PWM Mode
Using One PWM Signal and Additional RC Filters
Copyright © 2011, Texas Instruments Incorporated 25
Product Folder Link(s): AFE030