MICRF022BM TR Micrel Inc, MICRF022BM TR Datasheet - Page 7

• Manufacturer Part Number: MICRF022BM TR
• Manufacturer: Micrel Inc

Specifications of MICRF022BM TR

• Operating Band Frequency: 300 to 440MHz
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Modulation Type: ASK/OOK
• Product Depth (mm): 3.94mm
• Product Height (mm): 1.48mm
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Not Compliant

Functional Diagram
Resonator
Application Information and Functional
Description
Refer to Figure 1 “MICRF002 Block Diagram”. Identified in
the block diagram are the four sections of the IC: UHF
Downconverter,
Control, and Wakeup. Also shown in the figure are two
capacitors (CTH, CAGC) and one timing component,
usually a crystal or ceramic resonator. With the exception
of a supply decoupling capacitor, and antenna impedance
matching network, these are the only external components
needed by the MICRF002 to assemble a complete UHF
receiver.
For optimal performance is highly recommended that the
MICRF002 is impedance matched to the antenna, the
matching network will add an additional two or three
components.
Four control inputs are shown in the block diagram: SEL0,
SEL1, SWEN, and SHUT. Using these logic inputs, the
user can control the operating mode and selectable
features of the IC. These inputs are CMOS compatible, and
are internally pulled-up. IF Bandpass Filter Roll-off
response of the IF Filter is 5th order, while the demodulator
data filter exhibits a 2
Micrel, Inc.
July 2008
Ceramic
Cystal
REFOSC
C
AGC
SWEN
CAGC
SHUT
or
SEL0
SEL1
VDD
ANT
VSS
MICRF002
RF
Amp
f
T
OOK
nd
order response.
f
RX
Synthesizer
Reference
Demodulator,
Oscillator
Control
f
LO
Logic
f
IF
IF
Amp
Reference
Reference and Control
Figure 1. MICRF002 Block Diagram
Band-Pass Filter
430kHz
5th Order
and
UHF Downconverter
IF
Amp
7
Design Steps
The following steps are the basic design steps for using the
MICRF002 receiver:
Step 1: Selecting the Operating Mode
Fixed-Mode Operation
For applications where the transmit frequency is accurately
set (that is, applications where a SAW or crystal-based
transmitter is used) the MICRF002 may be configured as a
standard superheterodyne receiver (fixed mode). In fixed-
mode operation the RF bandwidth is narrower making the
receiver less susceptible to interfering signals. Fixed mode
is selected by connecting SWEN to ground.
Sweep-Mode Operation
When used in conjunction with low-cost L-C transmitters
the MICRF002 should be configured in sweep-mode. In
sweep-mode, while the topology is still superheterodyne,
the LO (local oscillator) is swept over a range of
frequencies at rates greater than the data rate. This
technique effectively increases the RF bandwidth of the
1. Select the operating mode (sweep or fixed)
2. Select the reference oscillator
3. Select the C
4. Select the C
5. Select the demodulator filter bandwidth
Detector
Control
Peak
AGC
Low-Pass Filter
Programmable
2nd Order
TH
AGC
capacitor
Resettable
capacitor
Counter
Switched-
Capacitor
Wakeup
Resistor
R
OOK Demodulator
SC
MICRF002/RF022
Compa-
rator
M9999-070808
WAKEB
DO
CTH
C
TH