KESRX04
260 to 470MHz. ASK Receiver with Power Down
Preliminary Information
DS4997 - 1.5 August 1998
The KESRX04 is a single chip ASK (Amplitude Shift Key)
Receiver IC. It is designed to operate in a variety of low power
radio applications including keyless entry, general domestic
and industrial remote control, RF tagging and local paging
systems.
The receiver offers an exceptionally high level of integration
and performance to meet the local oscillator radiation require-
ments of regulatory authorities world-wide. Functionally the
device works in the same way as the KESRX01 with the added
features of low supply voltage, in-band interference rejection
(anti-jamming detector), a 2 stage power down to enable
receiver systems to be implemented with less than 1mA supply,
and a wide IF bandwidth and drive stage to interface to an
external ceramic IF band pass filter at intermediate frequencies
from 0.2MHz to 15MHz.
The KESRX04 is an ideal receiver for difficult reception
areas where high level interferers would jam the wanted signal.
The anti-jamming circuit allows operation to be possible with
interfering signals which are more than 14dB stronger than the
wanted signal, without the cost penalties of increased IF
selectivity and frequency accuracy.
P
IFFLT1
IFDC1
IFFLT2
RSSI
PIN 1
REF. SPOT
IFIN
IFDC2
VCC
IFOUT
VCCRF
MIXIP
RFOP
VEERF
RFIN
AGC
PEAK
DATOP
DETB
PD
XTAL1
XTAL2
DF0
DF1
DF2
VCO1
VCO2
VEE
LF
DSN
(9.80/10.01)
QP28
Figure 1 Pin Connections (top view)
FEATURES
s
In-band interference rejection (typ. 14dB)
s
-103dBm Sensitivity (IF BW = 470kHz)
s
AGC around LNA and Mixer
s
Low supply voltage (3 to 6V)
s
2 stage power-down for low current applications
s
Interface for ceramic IF filters up to 15MHz
APPLICATIONS
s
Remote Keyless Entry
s
Security, tagging
s
Remote Controlled equipment
ORDERING INFORMATION
KESRX04/IG/QP1S (anti-static tubes)
KESRX04/IG/QP1T (tape and reel)
ABSOLUTE MAXIMUM RATINGS
Supply Voltage Vcc
Storage temperature,Tstg
Junction Temperature, Tj
RF Input power
-0.5V to +7V
-55 to 150°C
-55 to 150°C
+20dBm from 50Ω
agc
RF Input
mixer
Ceramic
IF Filter
RSSI detector
Anti-jam data filter
Slicer
SAW
Filter
LNA
Noise
reduction
Filter
Local
Oscillator
Sliced
data
Ref
Figure 2 Typical system application
KESRX04
PIN DESCRIPTION
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Symbol
IFFLT1
IFDC1
IFIN
IFDC2
VCC
IFOUT
VCCRF
MIXIP
RFOP
VEERF
RFIN
AGC
PEAK
DATOP
DSN
LF
VEE
VCO2
VCO1
DF2
DF1
DF0
XTAL2
XTAL1
PD
DETB
RSSI
IFFLT2
Function
Noise reducing IF filter
Log amp dc stability capacitor
Log amp input
Log amp dc stability capacitor
Positive supply
IF output to external IF filter
Positive supply for RF circuits
Mixer input
Output from LNA
Negative supply for RF circuits
Input to LNA
RF AGC time constant
Data signal peak detect
Sliced data output
Data slice level
PLL loop filter
Negative supply
Voltage controlled oscillator
Voltage controlled oscillator
Data filter
Data filter
Data filter
Crystal oscillator
Crystal oscillator
Power down
Anti-jam detector input
RSSI output
Noise reducing IF filter
DESCRIPTION
The single-conversion super-heterodyne receiver approach
is now generally considered the way forward for ISM band type
applications because of lower cost, superior selectivity, lower
radiation, and flexibility over other techniques. For power-
conscious, hand-held applications KESRX04 provides im-
proved performance and flexibility on a lower 3.0V supply and
a power-down feature allows faster switch-on times for use in
a pulsed power saving mode.
Although this is a relatively simple receiver, the flexibility of
using an external IF filter allows the designer to choose both
the selectivity and the IF in order to optimise the performance
for a wide range of applications and locations world wide.
The KESRX04, with its Anti-jamming detector circuit, is an
ideal ASK / OOK receiver for difficult reception areas caused
by interference such as “Amateur Radio Repeater Stations”
and Wireless Stereo Head-Phones”. Operation is possible
with interfering signals which are more than 14dB stronger that
the wanted signal (IF bandwidth = 470kHz.), without the cost
penalities of increased IF selectivity and frequency accuracy.
Figure 2 is the system block diagram for the device with an
external ceramic IF filter, SAW fillter and noise reduction filter.
2
KESRX04
ELECTRICAL CHARACTERISTICS Test conditions
T amb = –40°C to + 85°C, V
CC
= 3.0V to 6.0V. These characteristics are guaranteed by either device characterisation, production
test and or design. They apply within the specified ambient temperature and supply voltage ranges unless otherwise stated using
test circuit Figure 12.
Characteristic
Supply voltage
Ambient temperature
Test Frequency
local Oscillator
Symbol
V
CC
Ta
Min
3.0
–40
470
480.7
Value
Typ
Max
6.0
+85
Units
V
°C
MHz
MHz
local oscillator frequency
configured for high side injection,
except where otherwise specified
Conditions
ESD Protection:
All pins meet 2kV Human Body Model requirement. Except pins 9 and 11, which are limited to 700V
and pins 18 and 19 which are limited to 1.00kV.
ELECTRICAL CHARACTERISTICS D.C.
T amb = –40°C to + 85°C, V
CC
= 3.0V to 6.0V. These characteristics are guaranteed by either device characterisation production
test and or design. They apply within the specified ambient temperature and supply voltage ranges unless otherwise stated.
Parameter
Supply Current
Receive mode (PD2)
Power down (PD1)
Icc
Icc1
3.7
0.33
4.5
0.5
mA
mA
All. PD=High. RF input <-50dBm.
All. PD=Vcc/2 or
high impedance source.
Vcc = 3 to 6.0V (4)
Power down (PD0)
Icc2
33
50
µA
All. PD=low
Symbol
Min
Value
Typ
Units
Max
Condition
ELECTRICAL CHARACTERISTICS A.C
Parameter
Input frequency range
Intermediate Frequency
Sensitivity (test fixture)
Sensitivity (application)
Symbol
Min
fs
IF
Vin(min)
Vin(min)
260
0.2
8.0
1.5
Value
Typ
Max
470
15.0
23.0
MHz
MHz.
µVrms
µVrms
All
All. (8)
20kB/s data rate at 470MHz. (1)
Circuit as Figure 11 with SAW filter
removed1kB/s data rate at
433.92MHz. (3)
Overload Performance
PLL control line (pin 16)
To achieve 90% of final
value PD0 to PD2
PLL control line (pin 16)
To achieve 90% of final
value PD1 to PD2
Data output Voltage High
Data output Voltage Low
Conducted emissions
ts3
1.0
3.0
mS
Vin(max)
ts2
0.5
2.23
2.0
4.0
Vrms
mS
20kB/s data rate at 470MHz. (2)
All. Circuit as Figure 11 (5)
Local Oscillator low side
Injection 423.33 MHz.
All. Circuit as Figure 11 (5)
Local Oscillator low side
Injection 423.33 MHz.
Ioh=+10µA
Iol=-10µA
All Figure 11 (6), local Osc. low
side injection = 423.3MHz
.
Units
Condition
Voh
Vol
Antenna
(LO)
Vcc-0.7V
0.7
5.6
100
Volt
Volt
µVrms
3
KESRX04
ELECTRICAL CHARACTERISTICS A.C.
(continued)
These characteristics are typical values measured for a limited sample size. They are not guaranteed by production test.
They are only given as a design guide to assist during the design-in phase of KESRX04.
Parameter
Symbol
Value
Units
Condition
Min
Anti-jam rejection
Typ
+14
Max
dB
Unmodulated interfering signal
= -76dBm 433.82MHz. OOK
modulated wanted signal =
-90dBm 433.92MHz Figure 5 (7)
Internal RF Amplifier
Parallel input impedance
Parallel input impedance
Parallel output impedance
Parallel output impedance
Noise Figure
Rfin
Rfin
Rfout
Rfout
NF
1.0 // 1.8
1.6 // 1.9
8.8 // 1.7
18 // 1.8
4.5
Noise matching Impedance
1dB compression point
(input referred)
Rfin
1.0 // 4.6
KΩ // pF Fs=434MHz, Vcc= 5V,
Tamb =25°C
KΩ // pF Fs=315MHz, Vcc= 5V,
Tamb =25°C
KΩ // pF Fs=434MHz, Vcc= 5V,
Tamb =25°C
KΩ // pF Fs=315MHz, Vcc= 5V,
Tamb =25°C
dB
Fs=434MHz; Vcc= 5V,
Tamb =25°C matched 50ohm
environment input and output
KΩ // nH Fs=434MHz, Vcc= 5V,
Tamb =25°C
dBm
Fs=434MHz, Vcc= 5V,
Tamb =25°C matched 50ohm
environment input and output
Fs=434MHz., Vcc= 5V,
Tamb =25°C O/P matched to
Mixer input impedance
RF Amplifier is
conditionally
stable
Rfin
-20
Amplifier gain
RFamp
13
dB
MIXER
Parallel input impedance
Parallel input impedance
Output impedance
Noise Figure
(Double side band
measurement)
MIXIP
MIXIP
IF1
1.6 // 1.8
1.6 // 1.8
300
KΩ // pF Fs=434MHz, Vcc= 5V,
Tamb =25°C
KΩ // pF Fs=315MHz, Vcc= 5V,
Tamb =25°C
Ω
Fs=10.7MHz, Vcc= 5V,
Tamb =25°C
dB
Fs=434MHz; Vcc= 5V,
Tamb =25°C
matched 50ohm environment
input and output
Fs=434MHz., Vcc= 5V,
Tamb =25°C Measured at
input to ceramic filter. Includes
6dB matching loss
NF
10
Mixer conversion gain
Amix
9
dB
IF Strip (RSSI)
IF2 input impedance
4.0
KΩ
IF=10.7MHz, Vcc= 5V,
Tamb =25°C
IF gain of log amp
Alog
80
dB
All, Vcc= 5V, Tamb =25°C
4
KESRX04
Notes:
1.
The Sensitivity of the test fixture Figure 12 is degraded by loading the input to RF amplifier with 50 ohms, lack of image
rejection and increasing the data filter bandwidth to 50kHz. Sensitivity is defined as the average signal level measured
at the input necessary to achieve a bit error ratio of 0.01 where the input signal is a return to zero pulse at 470MHz.,with
an average duty cycle of 50%, 20kB/s data rate with the receiver bandwidth set to 470kHz.
Peak RF input level, pin RFIN, to overload the demodulator with the AGC operating. Equivalent to +7dBm for 50 ohm
input impedance. Where the input signal is a return to zero pulse at 470MHz. with an average duty cycle of 50%.
20kB/s data rate with the receiver bandwidth set to 470kHz.
Sensitivity is defined as the average signal level measured at the input necessary to achieve a bit error ratio of 0.01 where
the input signal is a return to zero pulse with an average duty cycle of 50%, 1kB/s data rate. Equivalent to -103dBm for
50ohm input impedance. Does not include insertion loss of SAW filter at RF input but does include IF filter of 470kHz
3dB bandwidth and a data filter bandwidth of 5kHz. This equates closely to a measurement of tangential sensitivity.
The performance of the power down option PD1 to PD2 cannot be guaranteed below 3V for temperatures less than 0°C
Time taken for PLL lock voltage to achieve 90% transition point of the control signal and the VCO frequency to achieve
within 470kHz of the final frequency. The time taken to acquire PLL acquisition is governed by the PLL loop filter (C12,
C1 and R2) and the crystal oscillator components (XTAL1, C13 and C14). The dominant term for PLL aquistion is the start-
up time of the crystal oscillator circuit, provided the PLL loop filter settling time is much less than the crystal oscillator start-
up time. Figure 6 illustrates a suitable test setup for measuring the acquisition time of the PLL. The electrical
characterisation parameters are based on the following set of conditions:
Crystal Oscillator circuit
C13 = C14
=
15pF
XTAL 1
Freq.
6.6128 MHz.
ESR
15.3
Ω
L
85.36 mH
C0
1.83 pF
C1
6.8 fF
PLL loop filter
C12 = 1.5 nF,
C1 = 180pF
R1 = 10KΩ
6.
Local oscillator power fed back into 50ohm source at antenna input (RF input). Measured with RF input matching network
shown in Figure 11.
In-band interference rejection for an unmodulated interfering signal at 100kHz. low side from the wanted modulated signal
at 433.92MHz. to achieve a Bit Error Rate =0.01. Figure 5 illustrates a suitable test set-up for measuring the interference
rejection and selectivity of the receiver.
Wanted signal =
(1kB/s. 50% duty cycle)
Interfering signal =
(unmodulated)
-90dBm at 433.92MHz.
2.
3.
4.
5.
7.
-76dBm at 433.82MHz.
Interference rejection typically equals +14dBm.
i.e. in-band interfering signal is 14dBm above the wanted signal level at –90dBm.
8.
Actual intermediate frequency determined by choice of crystal and external ceramic filter.
5
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