UM220-IV M0 Hardware Reference Design
2
2. Reference Circuit Using a Passive Antenna
To ensure the system performance, low noise amplifier and filter should be added
between the passive antenna and the module RF_IN
The VCC_RF output of the module is recommended for power supply with LNA
RF wire (Antenna
→ LNA → SAW → RF_IN), note the impedance matching at 50Ω
Figure 2 Reference Circuit Using a Passive Antenna
A1
UM220-IV-M0
nREST
9
NC2
13
TIMEPULSE
4
NC1
5
NC3
15
VCC_RF
14
GND
10
RF_IN
11
GND
12
VCC_IO
7
NC6
18
NC4
16
NC5
17
TXD
2
RXD
3
V_BCKP
6
VCC
8
GND
1
FB1
220@100MHz
VCC_RF
GND
C12
100nF
VBCKP
VCC
：
2.8V~3.6V
VBCKP
：
1.4V~3.6V
R1
1K
Active Low
R2
0
R5
0
nRESET
GND
RXD
TXD
GND
GND
C6
10 uF
GND
VCC
C5
100nF
+3V
TXD
RXD
C9
100nF
C11
100nF
C10
100nF
C7
100nF
U3
MAX
DIN1
11
DIN2
10
ROUT1
12
ROUT2
9
DOUT1
14
DOUT2
7
RIN1
13
RIN2
8
V+
2
C1+
1
C1-
3
C2+
4
C2-
5
V-
6
VCC
16
GND
15
GND
GND
GND
C8
100nF
GND
GND
GND
J2
DB9
5
9
4
8
3
7
2
6
1
10
11
R3
100
R4
100
GND
MAX
U1
GND#1
1
GND#2
2
RFIN
3
VCC
4
SHDN#
5
RFOUT
6
U2
TA0757A
GND#2
3
OUT
4
GND#3
5
GND#1
2
IN
1
L1
6.8nH
C3
1uF
C4
100nF
GND
GND
C2 100pF
C1 100pF
J1
Passiv e Ant
1
2
3
4
5
GND
VCC_RF
