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

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 CTH capacitor

4. Select the CAGC 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