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

MICRF003 / 033

QwikRadio

900 MHz UHF Receiver

Preliminary Information

General Description

The MICRF003 is a single chip OOK (ON-OFF Keyed) Receiver IC for
remote wireless applications, employing Micrel's latest QwikRadio

technology. This device is a true "antenna-in, data-out" monolithic device. All
RF and IF tuning is accomplished automatically within the IC, which
eliminates manual tuning, and reduces production costs. Receiver functions
are completely integrated. The result is a highly reliable yet extremely low
cost solution for high volume wireless applications. Because the MICRF003
is a true single-chip radio receiver, it is extremely easy to apply, minimizing
design and production costs, and improving time to market.

The MICRF003 provides two fundamental modes of operation, FIXED and
SWP. In FIXED mode, the device functions like a conventional
Superheterodyne receiver, with an (internal) local oscillator fixed at a single
frequency based on an external reference crystal or clock. As with any
conventional superheterodyne receiver, the transmit frequency must be
accurately controlled, generally with a crystal or SAW (Surface Acoustic
Wave) resonator.

In SWP mode, the MICRF003 sweeps the (internal) local oscillator at rates
greater than the baseband data rate. This effectively "broadens" the RF
bandwidth of the receiver to a value equivalent to conventional super-
regenerative receivers. Thus the MICRF003 can operate with less
expensive LC transmitters without additional components or tuning, even
though the receiver topology is still superheterodyne. In this mode the
reference crystal can be replaced with a less expensive

0.5% ceramic

resonator.

The MICRF003 provides two additional key features: (1) a Shutdown Mode,
which may be used for duty-cycle operation, and (2) a "Wakeup" function,
which provides a logical indication of an incoming RF signal. These features
make the MICRF003 ideal for low and ultra-low power applications, such as
RKE and RFID.

All post-detection (demodulator) data filtering is provided on the MICRF003,
so no external filters need to be designed. Any one of four filter bandwidths
may be selected externally by the user. Nominal filter bandwidths range in
binary steps, from 0.75kHz to 6kHz (SWP mode) or 2.8kHz to 22.4kHz
(FIXED mode). The user only needs to program the appropriate filter
selection based on data rate and code modulation format.

Features

Complete 900 MHz Band receiver on a monolithic IC

UHF Frequency range 800 to 1000 MHz

Typical range over 170 meters with monopole antenna

Data rates to 5kbps (SWP), 20kbps (FIXED)

Automatic tuning, no manual adjustment

No Filters or Inductors required

Low Operating Supply Current--4mA @ 868MHz

Shutdown Mode for Duty-Cycle Operation in excess of

100:1

Wakeup Function to Enable External Decoders and

Microprocessors

Very low RF re-radiation at the antenna

CMOS logic interface to standard decoder and

microprocessor ICs

Extremely low external part count

Applications

Automotive Remote Keyless Entry

Security Systems

Low Rate Data Modems

Remote Meter Data Collection

Typical Operating Circuit

915 MHz, 2400 bps OOK

ISM Band RECEIVER

QwikRadio

October 1999

MICRF003

MICRF003

Micrel

Pin Description (Pin numbers for the 8-pin version are identified in parentheses)

Pin Number

Pin Name

Pin Function

SEL0

This pin, in conjunction with SEL1, programs the desired Demodulator Filter Bandwidth. This pin is internally
pulled-up to VDDRF. See Table 1.

2/3

VSSRF

This pin is the ground return for the RF section of the IC. The bypass capacitor connected from VDDRF to
VSSRF should have the shortest possible lead length. For best performance, connect VSSRF to VSSBB at the
power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

(1)

VSSRF

This pin is the ground return for the IC. The bypass capacitor connected from VDDRF to VSSRF should have
the shortest possible lead length.

(2)

ANT

This is the receive RF input, internally ac-coupled. Connect this pin to the receive antenna. Input impedance is
high (FET gate) with approximately 2pF of shunt (parasitic) capacitance. For applications located in high
ambient noise environments, a fixed value band-pass network may be connected between the ANT pin and
VSSRF to provide additional receive selectivity and input overload protection. (See "Application Note TBD".)

VDDRF

This pin is the positive supply input for the RF section of the IC. VDDBB and VDDRF should be connected
directly at the IC pins. Connect a low ESL, low ESR decoupling capacitor from this pin to VSSRF, as short as
possible.

VDDBB

This pin is the positive supply input for the baseband section of the IC. VDDBB and VDDRF should be
connected directly at the IC pins.

(3)

VDDRF

This pin is the positive supply input for the IC. Connect a low ESL, low ESR decoupling capacitor from this pin
to VSSRF, as short as possible.

(4)

CTH

This capacitor extracts the (DC) average value from the demodulated waveform, which becomes the reference
for the internal data slicing comparator. Treat this as a low-pass RC filter with source impedance of nominally
90kohms ( for REFOSC frequency Ft = 6.75MHz, see "Application Note TBD"). A standard

20% X7R

ceramic capacitor is generally sufficient.

N/C

Unused Pin

VSSBB

This is the ground return for the baseband section of the IC. The bypass and output capacitors connected to
VSSBB should have the shortest possible lead lengths. For best performance, connect VSSRF to VSSBB at
the power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

(5)

The output data signal. CMOS level compatible.

(6)

SHUT

A logic input for Shutdown Mode control. Pull this pin low to place the IC into operation. This pin in internally
pulled-up to VDDRF.

WAKEB

An output signal, active low when the IC detects an incoming RF signal, determined by monitoring for data
preamble. CMOS level compatible.

(7)

CAGC

Integrating capacitor for on-chip AGC (Automatic Gain Control). The Decay/Attack time-constant (TC) ratio is
nominally set as 10:1. Use of 0.47uF or greater is strongly recommended for best range performance. Use
low-leakage type capacitors for duty-cycle operation (Dip Tantalum, Ceramic, Polyester). (See "Application Note
TBD.)

SEL1

This pin, in conjunction with SEL0, programs the desired Demodulator Filter Bandwidth. This pin in internally
pulled-up to VDDRF. See Table 1.

(8)

REFOSC

This is the timing reference for on-chip tuning and alignment. Connect either a ceramic resonator or crystal
(mode dependent) between this pin and VSSBB, or drive the input with an AC coupled 0.5Vpp input clock. Use
ceramic resonators without integral capacitors. Note that if operating in FIXED mode, a crystal must be used;
however in SWP mode, one may use either a crystal or ceramic resonator. See "Application Note TBD" for
details on frequency selection and accuracy.

SWEN

This logic pin controls the operating mode of the MICRF003. When SWEN = HIGH, the MICRF003 is in SWP
mode. When SWEN = LOW, the device operates as a conventional single-conversion superheterodyne
receiver. (See "Application Note TBD" for details.) This pin is internally pulled-up to VDDRF.

SEL0

SEL1

Demodulator Bandwidth (Hz)

SWP Mode FIXED Mode

6000 22400

3000 11200

1500 5600

750 2800

Table 1

Nominal Demodulator (Baseband) Filter Bandwidth

vs. SEL0, SEL1 and Mode

QwikRadio

October 1999

MICRF003

MICRF003

Micrel

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VDDRF, VDDBB)..................................+7V
Voltage on any I/O Pin.........................VSS-0.3 to VDD+0.3
Junction Temperature...............................................+150

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

C to + 150

Lead Temperature (soldering, 10 seconds)..............+ 260

Operating Ratings

Supply Voltage (VDDRF, VDDBB)....................4.75V to
5.5V
Ambient Operating Temperature (TA)..........-40

C to

+105

Package Thermal Resistance

ja (8 Pin SOIC).....120

C/W

Package Thermal Resistance

ja (16 Pin SOIC).....120

C/W

Electrical Characteristics

Unless otherwise stated, these specifications apply for Ta = -40

C to 105

C, 4.75<VDD<5.5V. All voltages are with respect

to Ground; Positive currents flow into device pins. CAGC = 4.7µF, CTH = .047µF, VDDRF = VDDBB = VDD. REFOSC
frequency = 6.75MHz.

Parameter

Test Conditions

MIN

TYP

MAX

UNITS

Power Supply

Operating Current

10:1 Duty Cycle

400

Standby Current

SHUT = VDD

RF/IF Section

Receiver Sensitivity

Note 1, 3

-95

dBm

IF Center Frequency

Note 4

2.37

MHz

IF 3dB Bandwidth

Note 3, 4

1.18

MHz

Receive Data Rate

FIXED Mode, Manchester Encoded Data

kbps

Receive Data Rate

SWP Mode, Manchester Encoded Data

kbps

RF Input Range

800

1000

MHz

Receive Modulation Duty-Cycle

Maximum Receiver Input

Rs = 50

-20

dBm

Spurious Reverse Isolation

ANT pin, Rs = 50

Note 2

Vrms

AGC Attack / Decay ratio

T(Attack) / T(Decay)

0.1

AGC Leakage Current

Ta = 85

200

Local Oscillator Stabilization Time

To 1% of Final Value

2.5

msec

Demod Section

CTH Source Impedance

Note 5

90k

CTH Source Impedance Variation

-15

+15

CTH Leakage Current

Ta = 85

200

Demod Filter Bandwidth

SEL0 = SEL1 = SWEN = VDD, Note 4, 6

5730

Demod Filter Bandwidth

SEL0 = SEL1 = VDD, SWEN = VSS,
Note 4, 6

21500

Digital/Control Section

REFOSC Input Impedance

200k

Input Pullup Current

SEL0, SEL1, SWEN, SHUT=VSS

µA

Input High Voltage

SEL0, SEL1, SWEN

0.8VDD

Input Low Voltage

SEL0, SEL1, SWEN

0.2VDD

Output Current

DO, WAKEUP pins, Push-Pull

µA

Output High Voltage

DO, WAKEUP pins, Iout = -1µA

0.9VDD

Output Low Voltage

DO. WAKEUP pins, Iout = +1µA

0.1VDD

Output Tr, Tf

DO, WAKEUP pins, Cload=15pF

µsec

QwikRadio

October 1999

MICRF003

MICRF003

Micrel

Note 1: Sensitivity is defined as the average signal level measured at the input necessary to achieve 10e-2 Bit Error Rate (BER). The input

signal is defined as a return-to-zero (RZ) waveform with 50% average duty cycle (e.g., Manchester Encoded Data) at a data rate of
600bps. The RF input is assumed to be matched into 50

Note 2: Spurious reverse isolation represents the spurious components which appear on the RF input (ANT) pin measured into 50

with an

input RF matching network.

Note 3: Sensitivity, a commonly specified Receiver parameter, provides an indication of the Receiver's input referred noise, generally input

thermal noise. However, it is possible for a more sensitive receiver to exhibit range performance no better than that of a less
sensitive receiver, if the "ether" noise is appreciably higher than the thermal noise. "Ether" noise refers to other interfering "noise"
sources, such as FM radio stations, pagers, etc.

A better indicator of achievable receiver range performance is usually given by its Selectivity, often stated as Intermediate Frequency
(IF) or Radio Frequency (RF) bandwidth, depending on receiver topology. Selectivity is a measure of the rejection by the receiver of
"ether" noise. More selective receivers will almost invariably provide better range. Only when the receiver selectivity is so high that
most of the noise on the receiver input is actually thermal will the receiver demonstrate sensitivity-limited performance.

Note 4: Parameter scales linearly with REFOSC frequency Ft. For any REFOSC frequency other than 6.75MHz, compute new parameter

value as the ratio [(REFOSC FREQ (in MHz)) / 6.75] * [Parameter Value @ 6.75MHz]. Example: For REFOSC Freq. Ft =
7.12MHz, [Parameter Value @ 7.12MHz] = (7.12 / 6.75) * [Parameter Value @ 6.75MHz].

Note 5: Parameter scales inversely with REFOSC frequency Ft. For any REFOSC frequency other than 6.75MHz, compute new parameter

value as the ratio [6.75 / (REFOSC FREQ (in MHz))] * [Parameter Value @ 6.75MHz]. Example: For REFOSC Freq. Ft =
7.12MHz, [Parameter Value @ 7.12MHz] = (6.75 / 7.12) * [Parameter Value @ 6.75MHz].

Note 6: Demod filter bandwidths are related in a binary manner, so any of the other (lower) nominal filter values may be derived simply by

dividing this parameter value by 2, 4, or 8 as desired.

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