June 2002

MICRF103

Micrel

MICRF103

QwikRadioTM UHF ASK Transmitter

Final

General Description

The MICRF103 is a single chip Transmitter IC for remote
wireless applications. The device employs Micrel's latest
QwikRadioTM technology. This device is a true "data-in,
antenna-out" monolithic device. All antenna tuning is accom-
plished automatically within the IC which eliminates manual
tuning, and reduces production costs. The result is a highly
reliable yet extremely low cost solution for high volume
wireless applications. Because the MICRF103 is a true
single-chip radio transmitter, it is easy to apply, minimizing
design and production costs, and improving time to market.

The MICRF103 uses a novel architecture where the external
antenna is tuned by the internal UHF synthesizer. This
transmitter is designed to comply worldwide UHF unlicensed
band international radio regulations. The IC is compatible
with virtually all ASK/OOK (Amplitude Shift Keying/On-Off
Keyed) UHF receiver types from wide-band super-regenera-
tive radios to narrow-band, high performance super-hetero-
dyne receivers. The transmitter is designed to work with
transmitter data rates up to 115k bits per second.

The automatic tuning in conjunction with an external resistor,
insures that the transmitter output power stays constant at
maximum regulatory transmit power limits for the life of the
battery.

When coupled with Micrel's family of QwikRadioTM receivers,
the MICRF103 provides the lowest cost and most reliable
remote actuator and RF link system available.

Typical Application

VDD

VSS

REFOSC

ASK

MICRF103

Note: Example for 868MHz

ASK DATA INPUT

RP2
6.8k

0.1

4.7

RP1
100k

+5V

8.2pF

100pF

1.0pF

10nH

1.0pF

27nH

ANTP

ANTM

STBY

100k

SAW Filter

Monopole

PCB Antenna

Figure 1

Features

ˇ Complete UHF transmitter on a monolithic chip
ˇ Frequency range 800MHz to 1GHz
ˇ Data rates to 115kbps
ˇ Automatic antenna alignment, no manual adjustment
ˇ Low external part count
ˇ Low standby current <1

Applications

ˇ Remote keyless entry systems (RKE)
ˇ Remote fan/light control
ˇ Garage door opener transmitters
ˇ Remote sensor data links

Ordering Information

Part Number

Temperature Range

Package

MICRF103BM

C to +85

8-Pin SOIC

Micrel, Inc. ˇ 1849 Fortune Drive ˇ San Jose, CA 95131 ˇ USA ˇ tel + 1 (408) 944-0800 ˇ fax + 1 (408) 944-0970 ˇ http://www.micrel.com

QwikRadio is a trademark of Micrel, Inc. The QwikRadio ICs were developed under a partnership agreement with AIT of Orlando, Florida.

MICRF103

Micrel

MICRF103

June 2002

Pin Description

Pin Number

Pin Name

Pin Function

Power Control Input. The voltage at this pin should be set between 0.1V to
0.4V for normal operation.

VDD

Positive power supply input for the IC.

VSS

This pin is the ground return for the IC. A power supply bypass capacitor
connected from VDD to VSS should have the shortest possible path.

REFOSC

This is the timing reference frequency which is the transmit frequency
divided by 64. Connect a crystal (mode dependent) between this pin and
VSS, or drive the input with an AC coupled 0.5Vpp input clock. See

Refer-

ence Oscillator section in this data sheet under Electrical Characteristics.

STBY

Input for transmitter stand-by control pin is pulled to VDD for transmit
operation and VSS for stand-by mode.

ANTM

Negative RF power output to drive one side of the transmit antenna.

ANTP

Positive RF power output to drive the other side of the transmit antenna.

ASK

Amplitude Shift Key modulation data input pin. For CW operation, connect
this pin to VDD.

Pin Configuration

VDD

VSS

REFOSC

ASK

ANTP

ANTM

STBY

MICRF103BM

June 2002

MICRF103

Micrel

Electrical Characteristics

Specifications apply for 4.75V < V

< 5.5V, V

= 0.35V, T

= 25

C, freq

REFOSC

= 13.5625MHz, STBY = V

. Bold values indicate

C unless otherwise noted.

Parameter

Condition

Min

Typ

Max

Units

Power Supply

Standby Supply Current, I

STBY

< 0.5V

0.10

MARK Supply Current, I

@868MHz

26.5

@915MHz

27.5

SPACE Supply Current, I

OFF

@868MHz

@915MHz

MARK/SPACE Ratio

33%@868MHz

33%@915MHz

RF Output Section and Modulation Limits:

Maximum Power Level, P

OUT

@868MHz (EIRP)

-3

dBm

@915MHz (EIRP)

-3

dBm

Output Power Variation

over supply and temperature

dBm

Extinction ratio for ASK

dBc

Varactor tuning range

Note 5

2.6

3.0

3.3

Reference Oscillator Section

Reference Oscillator Input

300

Impedance

Reference Oscillator Source

5.0

Current

Reference Oscillator Input

0.2

1.0

Voltage (peak-to-peak)

Digital / Control Section

Calibration Time

note 7, ASK=HIGH

Power Amplifier Output Hold-off

note 4, STDBY transition from LOW to HIGH

Time from STBY

crystal, ESR < 20

Transmitter Stabilization Time

from external reference (500mVpp)

From STBY

crystal, ESR < 20

Maximum Data rate

- ASK modulation

duty cycle of the modulating signal = 50%

115

kbits/s

STBY HIGH

enable voltage

0.8V

STBY LOW

0.1V

ASK Pin

, input high voltage

0.8V

, input low voltage

0.1V

ASK Input Current

ASK = 0V, 5.0V input current

0.1

Absolute Maximum Ratings

(Note 1)

Supply Voltage(V

) ..................................................... +6V

Voltage on I/O Pins ............................. V

0.3 to V

+0.3

Storage Temperature Range ................... -65

C to + 150

Lead Temperature (soldering, 10 seconds) ........... + 300

ESD Rating, Note 3

Operating Ratings

(Note 2)

Supply Voltage (V

) .................................... 4.75V to 5.5V

Maximum Supply Ripple Voltage ............................... 10mV

PC Input Range ...................................... 0.1V < V

< 0.4V

Ambient Operating Temperature (T

) ........ 40

C to +85

Programmable Transmitter Frequency Range:

........................................................ 800MHz to 1GHz

MICRF103

Micrel

MICRF103

June 2002

Note 1.

Exceeding the absolute maximum rating may damage the device.

Note 2.

The device is not guaranteed to function outside its operating rating.

Note 3.

Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

Note 4.

After the release of the STDBY, the device requires an initialization time to settle the REFOSC and the internal PLL. The first MARK state
(ASK HIGH) after exit from STDBY needs to be longer than the initialization time. The subsequent low to high transitions will be treated as
data modulation whereby the envelope transition time will apply.

Note 5.

The varactor capacitance tuning range indicates the allowable external antenna component variation to maintain tune over normal production
tolerances of external components. Guaranteed by design not tested in production.

Note 6.

For the ASK modulation scheme, the part will accept ASK (digital ON/OFF) input and will transmit the data with a finite extinction ratio and the
pin will set the MARK power level.

Note 7.

When the device is first powered up or it loses power momentarily, it goes into the calibration mode to tune up the transmit antenna.

Test Circuit

VDD

VSS

REFOSC

ASK

MICRF103

ANTM

ANTP

STBY

100

4:1

680pF

7.1nH

680pF

200

100

Part Number MICRF103