
4-4
Pin Descriptions
PIN
SYMBOL
DESCRIPTION
1
AGC1_BYP+
DC feedback pin for AGC amplifier 1. Requires good decoupling and minimum wire length to a solid signal ground.
2
AGC1_In+
Non-inverting analog input of AGC amplifier 1.
3
GND
Ground. Connect to a solid ground plane.
4
AGC_Sel
This pin selects either differential or single ended input configuration for the first stage AGC. Ground this pin for
differential input configuration. Leave it floating for single ended input configuration.
5,
AGC1_In-
Inverting analog input of AGC amplifier 1.
6,
AGC1_BYP-
DC feedback pin for AGC amplifier 1. Requires good decoupling and minimum wire length to a solid signal ground.
7, 8
GND
Ground. Connect to a solid ground plane.
9
LPF_V
CC
Supply pin for the Low pass filter. Use high quality decoupling capacitors right at the pin.
10
2V REF
Stable 2V reference voltage output for external applications. Loading must be higher than 10k
. A bypass
capacitor of at least 0.1
μ
F is required.
11
LPF_BYP
Internal reference bypass pin. This is the common voltage (V
CM
) used for the LPF digital thresholds. Requires
0.1
μ
F decoupling capacitor.
12
NC
Connected internally for test purposes. Pin must be left floating.
13
NC
Connected internally for test purposes. Pin must be left floating.
14
LPF_RXI_Out
Low pass filter in phase (I) channel receive output. Requires AC coupling.
15
LPF_RXQ_Out
Low pass filter quadrature (Q) channel receive output. Requires AC coupling.
16
LPF_Sel1
Digital control input pins. Selects four programed cut off frequencies for the receive channel. Tuning speed from
one cutoff to another is less than 1
μ
s.
SEL1
SEL0
CUTOFF FREQUENCY
SEL1
LO
LO
2.2MHz
HI
LO
HI
4.4MHz
HI
SEL0
LO
HI
CUTOFF FREQUENCY
8.8MHz
17.6MHz
17
LPF_Sel0
18
LPF_Tune1
These two pins are used to fine tune the Low pass filter cutoff frequency. A resistor connected between the two
pins (R
TUNE
) will fine tune both transmit and receive filters. Refer to the tuning equation in the LPF AC
specifications.
19
LPF_Tune0
20
GND
Ground. Connect to a solid ground plane.
21
LPF_RX_PE
Digital input control pin to enable the LPF receive mode of operation. Enable logic level is High.
22
GND
Ground. Connect to a solid ground plane.
23
NC
Connected internally for test purposes. Pin must be left floating.
24
NC
Connected internally for test purposes. Pin must be left floating.
25
NC
Connected internally for test purposes. Pin must be left floating.
26
NC
Connected internally for test purposes. Pin must be left floating.
27
LPF_RXQ-
Low pass filter inverting input of the receive quadrature channel. AC coupling is required. This input is normally
coupled to the negative output of the quadrature demodulator (Mod_RXQ-), pin 36.
28
LPF_RXQ+
Low pass filter non inverting input of the receive quadrature channel. AC coupling is required. This input is
normally coupled to the positive output of the quadrature demodulator (Mod_RXQ+), pin 35.
29
LPF_RXI-
Low pass filter inverting input of the receive in phase channel. AC coupling is required. This input is normally
coupled to the negative output of the in phase demodulator (Mod_RXI-), pin 34.
30
LPF_RXI+
Low pass filter non inverting input of the receive in phase channel. AC coupling is required. This input is normally
coupled to the positive output of the in phase demodulator (DEMOD_RXI-), pin 33.
31, 32
GND
Ground. Connect to a solid ground plane.
33
DEMOD_RXI+
In phase demodulator positive output. AC coupling is required. Normally connects to the non inverting input of the
Low pass filter (LPF_RXI+), pin 30.
34
DEMOD_RXI-
In phase demodulator negative output. AC coupling is required. Normally connects to the inverting input of the
Low pass filter (LPF_RXI-), pin 29.
HFA3761