RFRXD0420T-I/LQ Microchip Technology, RFRXD0420T-I/LQ Datasheet - Page 12

• Manufacturer Part Number: RFRXD0420T-I/LQ
• Description: IC RCVR 315/433MHZ ASK/FSK32LQFP
• Manufacturer: Microchip Technology

Specifications of RFRXD0420T-I/LQ

• Frequency: 300MHz ~ 450MHz
• Sensitivity: -106dBm
• Data Rate - Maximum: 80 kbps
• Modulation Or Protocol: ASK, FM, FSK
• Applications: Home Automation, Remote Sensing, RKE
• Current - Receiving: 9.2mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• For Use With: DV164102 - KIT DEV RFPICKIT KIT 1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Memory Size: -

rfRXD0420/0920
3.1.7
The LNA
pulled up to V
to 1IF
1IF
Important: To ensure LNA stability the V
must be connected to a low impedance ground.
As shown in Figure 3-6, components C1 and L1 make
up the tuned circuit and provide collector current via
pull-up. Together with decoupling capacitor C2, they
provided impedance matching between the LNA and
MIXER1. To a lesser extent, C1, L1, and C2 provide
band-pass filtering at the receive frequency (f
Component values depend on the selected receive
frequency. The challenge is to design the circuit with
the fewest components setting Q as high as possible
as limited by component tolerances. For a majority of
applications it is best to design a wide bandwidth tuned
circuit to account for manufacturing and component
tolerances. The best approach is to design the tuned
circuit using a filter simulation program. Table 3-3 lists
example component values for popular receive
frequencies.
FIGURE 3-6:
TABLE 3-3: LNA TUNED CIRCUIT EXAMPLE
DS70090A-page 12
These values are for design guidance only.
IN
433.92 MHz
868.3 MHz
input impedance is approximately 33 Ω || 1.5 pF.
315 MHz
915 MHz
IN
(Pin 4) via a series decoupling capacitor. The
OUT
LNA TUNED CIRCUIT
f
rf
(Pin 3) has an open-collector output. It is
DD
COMPONENT VALUES
via a tuned circuit. It is also connected
LNA OUTPUT TO MIXER1
EXAMPLE CIRCUIT.
C1
V
3
7.0 pF
3.0 pF
2.0 pF
2.0 pF
DD
C1
L1
C2
C Bypass
4
7.6 nH
6.8 nH
22 nH
15 nH
L1
SS
pin (Pin 1)
rf
6.0 pF
6.0 pF
3.0 pF
3.0 pF
).
C2
Preliminary
3.1.8
The 1IF+ (Pin 6) and 1IF- (Pin 7) are bias connections
to the MIXER1 balanced collectors. Both pins are
open-collector outputs and are individually pulled up to
V
bias example circuit.
FIGURE 3-7:
3.1.9
The IF filter defines the overall adjacent signal selectiv-
ity of the receiver. For a majority of applications, low-
cost 10.7 MHz ceramic IF filters are used. These are
available in a variety of bandwidths and packages.
IF filter bandwidth selection is a function of:
• modulation (ASK, FSK or FM)
• signal bandwidth
• frequency and temperature tolerances of the
The typical input and output impedance of ceramic
filters is 330 Ω. 1IF
330 Ω single-ended output impedance and provides a
direct match to the ceramic IF filter. The internal resis-
tance of the 2IF
order to terminate ceramic IF filters a 390 Ω resistor
can be paralleled to the 2IF
Figure 3-8 shows an example circuit schematic using a
10.7 MHz ceramic IF filter.
3.1.10 IF LIMITING AMPLIFIER EXTERNAL
FBC1 (Pin 12) and FBC2 (Pin 13) are connected to
external feedback capacitors. Figure 3-8 shows
component
capacitors.
DD
transmitter and receiver components
by a load resistor. Figure 3-7 shows a MIXER1
MIXER1 BIAS
INTERMEDIATE FREQUENCY (IF)
FILTER
FEEDBACK CAPACITORS
values
IN
MIXER1 BIAS EXAMPLE
CIRCUIT
(Pin 11) is approximately 2.2 kΩ. In
470 Ω
OUT
R1
6
and
V
DD
 2003 Microchip Technology Inc.
(Pin 9) has an approximately
V
7
connections
DD
IN
R2
470 Ω
and FBC2 (Pin 13).
for
these