Micrel MICRF010
June 2005
6
M9999-063005
(408) 955-1690
Functional Diagram
Figure 1. MICRF010 Block Diagram
Application Information and Function
Description
“MICRF010 Block Diagram” above shows the IC
partitioned into three sections: 1) UHF Downconverter, 2)
OOK Demodulator, 3) Reference and Control. Also shown
in the figure are two external capacitors (C
TH
, C
AGC
) and
one timing element, which is usually a crystal. With the
exception of a supply decoupling capacitor and antenna
impedance matching network, these are the only external
components needed by the MICRF010 to assemble a
complete UHF receiver.
For optimal performance it is highly recommended that the
MICRF010 is impedance-matched to the antenna. The
matching network will add an additional two or three
components.
The “SHUT” input is the only control input of the IC. It is
used in polling operation for decreasing DC current
consumption. This input is CMOS compatible and it is
internally pulled-up.
The IF Bandpass Filter Roll-off response of the IF Filter is
5th order, and the demodulator data filter has a 2nd order
response.
Design Steps:
The following steps are the basic design steps for using the
MICRF010 receiver:
1. Select the reference oscillator
2. Select the demodulator filter bandwidth
3. Select the C
TH
capacitor
4. Select the C
AGC
capacitor
Step 1: Selecting The Reference Oscillator
All timing and tuning operations on the MICRF010 are
derived from the internal Colpitts reference oscillator.
Timing and tuning is controlled through the REFOSC pin in
one of three ways:
1. Connect a crystal.
2. Drive this pin with an external timing signal.
The specific reference frequency required is related to the
system transmit frequency.
Crystal Selection
The smaller the crystal, the longer it takes for the oscillator
to start from a shutdown operation. If shorter start-up time
