MICRF008BM TR Micrel Inc, MICRF008BM TR Datasheet - Page 6

• Manufacturer Part Number: MICRF008BM TR
• Manufacturer: Micrel Inc

Specifications of MICRF008BM TR

• Operating Band Frequency: 300 to 440MHz
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• 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
Functional Description
The entire block diagram illustrates the basic structure of
the MICRF008YM. It is made of three sub-blocks, which
are the UHF Downconverter, the OOK Demodulator, and
the Reference and Control. Also shown in the figure are
two capacitors (CTH, and CAGC) and the reference
frequency device, usually a ceramic resonator. With the
exception of a supply decoupling capacitor and the
matching network on the antenna pin, these are all the
external components needed with the MICRF008YM to
make a complete UHF receiver. There is one control
input, the SEL0 pin. The purpose is to set the
demodulator filter bandwidth of either 2.4kHz or 4.8kHz,
and is set high or low according to the minimum pulse
width in the demodulated signal. The input is CMOS
compatible, and is pulled-up internally in the IC.
Receiver Operation
The MICRF008YM is a superheterodyne receiver
working in sweep mode. It is capable of data rates up to
9.6kbaud NRZ or 4.8kbaud Manchester encoded. The
MICRF008YM RF center frequency is controlled by a
completely integrated PLL/VCO frequency synthesizer
with frequency set by a ceramic resonator. The actual
Micrel, Inc.
August 2008
Resonator
Ceramic
REFOSC
SEL0
VCC
ANT
VSS
Reference and Control
Amp
RF
t
RF
Synthesizer
Reference
Oscillator
t
LO
Control
Logic
Figure 1. MICRF008 Block Diagram
mboer
t
IF
Amp
IF
UHF Downconverter
6
swept bandwidth is approximately 3% of the RF carrier
frequency. It makes an ideal part to work with LC-based
transmitters or other types of transmitters that are not
precise in nature and vary their frequency with time. In
sweep mode the LO frequency (local oscillator) is varied
in a rate much higher than the data signal, which results
in down-conversion of approximately 3% of the carrier
frequency present at the antenna pin. The low level RF
signal is amplified by the RF amp section and
downconverted by the mixer to the IF frequency which is
amplified and filtered internally in the device and further
amplified for the peak detector. The peak detector will
detect the IF and further filtering is accomplished in the
programmable low-pass filter. The detected/filtered
signal is compared with the DC value of the
demodulated signal in the data-slicer and a digital output
is provided from the DO pin
Data Slicing Level
Extraction of the DC value of the demodulated signal for
purposes of logic-level data slicing is accomplished by
an external capacitor CTH and the on-chip switched-
capacitor resistor RSC, indicated in the block diagram.
The effective resistance of RSC scales inversely
Switched-Cap
1MHz
Resistor
R
BC
OOK Demodulator
Amp
IF
Programmable
Low-Pass
Detector
Control
Peak
AGC
Filter
CAGC
M9999-080108
CTH
DO
MICRF008