Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
2
November 3, 1992 853-1679 08108
DESCRIPTION
The SA608 is a low voltage high performance
monolithic FM IF system incorporating a
mixer/oscillator, two limiting intermediate
frequency amplifiers, quadrature detector,
logarithmic received signal strength indicator
(RSSI), voltage regulator and audio and RSSI
op amps. The SA608 is available in 20-lead
dual-in-line plastic, 20-lead SOL
(surface-mounted miniature package) and
20-lead SSOP package.
The SA608 was designed for portable
communication applications and will function
down to 2.7V. The RF section is similar to
the famous NE605. The audio output is
buffered. The RSSI output has an internal
amplifier with the feedback pin accessible.
The SA608 also has an extra limiter output.
This signal is buffered from the output of the
limiter and can be used to perform frequency
check. This is accomplished by comparing a
reference frequency with the frequency check
signal using a comparator to a varactor or
PLL at the oscillator inputs.
FEATURES
•Low power consumption: 3.5mA typical at
3V
•Mixer input to >150MHz
•Mixer conversion power gain of 17dB at
45MHz
•XTAL oscillator effective to 150MHz (L.C.
oscillator or external oscillator can be used
at higher frequencies)
•102dB of IF Amp/Limiter gain
•2MHz limiter small signal bandwidth
•Temperature compensated logarithmic
Received Signal Strength Indicator (RSSI)
with a 90dB dynamic range
•Low external component count; suitable for
crystal/ceramic/LC filters
•Excellent sensitivity: 0.31µV into 50Ω
matching network for 12dB SINAD (Signal
to Noise and Distortion ratio) for 1kHz tone,
8kHz deviation with RF at 45MHz and IF at
455kHz
•SA608 meets cellular radio specifications
•Audio output internal op amp
•RSSI output internal op amp
•Buffered frequency check output
•Internal op amps with rail-to-rail outputs
•ESD protection: Human Body Model 2kV
Robot Model 200V
APPLICATIONS
•Portable cellular radio FM IF
•Cordless phones
•Narrow band cellular applications
(NAMPS/NTACS)
•RF level meter
•Spectrum analyzer
•Instrumentation
•FSK and ASK data receivers
•Log amps
•Portable high performance communication
receivers
•Single conversion VHF receivers
•Wireless systems
PIN CONFIGURATION
RF IN+
RF IN–
OSC-
OUT
OSCIN
RSSI
7
20 MIXER OUT
19
18 IF AMP IN
17
16 IF AMP OUT
15 GND
14 LIMITER IN
13
12
LIMITER
VCC
D, DK and N Packages
AUDIO
8
FREQ CHECK/ 9
QUADRATURE 10
IF AMP
LIM OUT (–)
IN
DECOUPLING
IF AMP
DECOUPLING
LIMITER
DECOUPLING
LIMITER
DECOUPLING
1
DECOUPLING 2
3
4
5
6
11 OUT (+)
RSSI
FEEDBACK
ORDERING INFORMATION
DESCRIPTION TEMPERATURE RANGE ORDER CODE DWG #
20-Pin Plastic Dual In-Line Package (DIP) -40 to +85°C SA608N 0408B
20-Pin Plastic Small Outline Large (SOL) package (Surface-mount) -40 to +85°C SA608D 0172D
20-Pin Plastic Shrink Small Outline Package (SSOP) (Surface-mount) -40 to +85°C SA608DK 1563
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 3
BLOCK DIAGRAM
20 19 18 17 16 15 14 13 12 11
10987654321
RSSI
IF
AMP
E B
VREG
OSCILLATOR
LIMITER
MIXER
QUAD
+– + –
AUDIO
ABSOLUTE MAXIMUM RATINGS
SYMBOL PARAMETER RATING UNITS
VCC Single supply voltage 7 V
TSTG Storage temperature range –65 to +150 °C
TAOperating ambient temperature range SA608 –40 to +85 °C
θJA Thermal impedance D package
DK package
N package
90
117
75 °C/W
DC ELECTRICAL CHARACTERISTICS
VCC = +3V, TA = 25°C; unless otherwise stated. LIMITS
SYMBOL PARAMETER TEST CONDITIONS SA608 UNITS
MIN TYP MAX
VCC Power supply voltage range 2.7 7.0 V
ICC DC current drain 3.5 4.2 mA
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 4
AC ELECTRICAL CHARACTERISTICS
TA = 25°C; VCC = +3V, unless otherwise stated. RF frequency = 45MHz + 14.5dBV RF input step-up; IF frequency = 455kHz; R17 = 2.4k; R18
= 3.3k; RF level = –45dBm; FM modulation = 1kHz with ±8kHz peak deviation. Audio output with de-emphasis filter and C-message weighted
filter. Test circuit 1. The parameters listed below are tested using automatic test equipment to assure consistent electrical characterristics. The
limits do not represent the ultimate performance limits of the device. Use of an optimized RF layout will improve many of the listed parameters.
LIMITS
SYMBOL PARAMETER TEST CONDITIONS SA608 UNITS
MIN TYP MAX
Mixer/Osc section (ext LO = 220mVRMS)
fIN Input signal frequency 150 MHz
fOSC Crystal oscillator frequency 150 MHz
Noise figure at 45MHz 6.2 dB
Third–order input intercept point (50Ω
source) f1 = 45.0; f2 = 45.06MHz
Input RF Level = –52dBm –9 dBm
Conversion power gain Matched 14.5dBV step–up 13.5 17 19.5 dB
50Ω source +2.5 dB
RF input resistance Single–ended input 8 kΩ
RF input capacitance 3.0 4.0 pF
Mixer output resistance (Pin 20) 1.25 1.5 kΩ
IF section IF amp gain 50Ω source 44 dB
Limiter gain 50Ω source 58 dB
Input limiting –3dB, R17 = 2.4k Test at Pin 18 –109 dBm
AM rejection 80% AM 1kHz 45 dB
Audio level235 60 80 mV
SINAD sensitivity RF level –110dB 17 dB
THD Total harmonic distortion –35 –50 dB
S/N Signal–to–noise ratio No modulation for noise 62 dB
IF RSSI output, R9 = 2kΩ1IF level = –118dBm 0.3 0.8 V
IF level = –68dBm .70 1.1 1.80 V
IF level = –23dBm 1.2 1.8 2.5 V
RSSI range 90 dB
RSSI accuracy +1.5 dB
IF input impedance 1.3 1.5 kΩ
IF output impedance 0.3 kΩ
Limiter input impedance 1.30 1.5 kΩ
Limiter output impedance (Pin 11) 200 Ω
Limiter output level (Pin 11) no load
5kΩ load 130
115 mVRMS
Frequency check/lim (–) output impedance (Pin 9) 200 Ω
Frequency check/lim (–) output level (Pin 9) no load
5kΩ load 130
115 mVRMS
RF/IF section (int LO)
Audio level 3V = VCC, RF level = –27dBm 120 mVRMS
System RSSI output 3V = VCC, RF level = –27dBm 2.2 V
System SINAD sensitivity RF level = –117dBm 12 dB
NOTE:
1. The generator source impedance is 50Ω, but the SA608 input impedance at Pin 18 is 1500Ω. As a result, IF level refers to the actual signal
that enters the SA608 input (Pin 18) which is about 21dB less than the “available power” at the generator.
2. By using 45kΩ load across the Quad detector coil, you will have Audio output at 115mV with –42dB distortion.
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 5
CIRCUIT DESCRIPTION
The SA608 is an IF signal processing system
suitable for second IF systems with input fre-
quency as high as 150MHz. The bandwidth
of the IF amplifier and limiter is at least 2MHz
with 90dB of gain. The gain/bandwidth dis-
tribution is optimized for 455kHz, 1.5kΩ
source applications. The overall system is
well-suited to battery operation as well as
high performance and high quality products
of all types.
The input stage is a Gilbert cell mixer with
oscillator. Typical mixer characteristics
include a noise figure of 6.2dB, conversion
gain of 17dB, and input third-order intercept
of –9dBm. The oscillator will operate in
excess of 200MHz in L/C tank configurations.
Hartley or Colpitts circuits can be used up to
100MHz for xtal configurations. Butler
oscillators are recommended for xtal
configurations up to 150MHz.
The output impedance of the mixer is a 1.5kΩ
resistor permitting direct connection to a
455kHz ceramic filter. The input resistance
of the limiting IF amplifiers is also 1.5kΩ.
With most 455kHz ceramic filters and many
crystal filters, no impedance matching
network is necessary. The IF amplifier has
43dB of gain and 5.5MHz bandwidth. The IF
limiter has 60dB of gain and 4.5MHz
bandwidth. To achieve optimum linearity of
the log signal strength indicator, there must
be a 12dB(v) insertion loss between the first
and second IF stages. If the IF filter or
interstage network does not cause 12dB(v)
insertion loss, a fixed or variable resistor or
an L pad for simultaneous loss and
impedance matching can be added between
the first IF output (Pin 16) and the interstage
network. The overall gain will then be 90dB
with 2MHz bandwidth.
The signal from the second limiting amplifier
goes to a Gilbert cell quadrature detector.
One port of the Gilbert cell is internally driven
by the IF. The other output of the IF is
AC-coupled to a tuned quadrature network.
This signal, which now has a 90° phase
relationship to the internal signal, drives the
other port of the multiplier cell.
The demodulated output of the quadrature
drives an internal op amp. This op amp is
configured as a unity gain buffer.
A log signal strength completes the circuitry.
The output range is greater than 90dB and is
temperature compensated. This log signal
strength indicator exceeds the criteria for
AMPs or TACs cellular telephone. This
signal is buffered through an internal unity
gain op amp. The frequency check pin
provides a buffered limiter output. This is
useful for implementing an AFC (Automatic
Frequency Check) function. This same
output can also be used in conjunction with
limiter output (Pin 11) for demodulating FSK
(Frequency Shift Keying) data. Both pins are
of the same amplitude, but 180° out of phase.
NOTE: Limiter or Frequency Check output
has drive capability of a 5kΩ minimum or
higher in order to obtain 120mVRMS output
level.
NOTE: dB(v) = 20log VOUT/VIN
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 6
MINI–CIRCUIT ZSC2–1B
AUDIO
C14
IFT1
C10
C9
C8
C7
C6 X1
R7
30.5
L2
SW3 SW4SW1
VCC
EXT.
LOC
OSC
44.545
45MHZ
R3
R1
R2
SW2
C3 C4
R4
51.1 C5
C2
C1
L1
R6
178 R8
39.2
”C” WEIGHTED
AUDIO
MEASUREMENT
CIRCUIT
45.06
MHZ
50.5
2430
3880
96.5
32.6 71.5
C24 C22 C20 C19
C18
C15
C16
C17
FLT2
SW7 SW6 SW5
SW8
SW9
C23 C21
R17
2.4k
FLT1
–25dB,
1500/50Ω PAD –10dB,
50/50Ω PAD –29dB,
929/50Ω PAD –10.6dB,
50/50Ω PAD –36dB,
156k/50Ω PAD
100pF NPO Ceramic
390pF NPO Ceramic
22pF NPO Ceramic
1nF Ceramic
10.0pF NPO Ceramic
10pF NPO Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
2.2µF
100nF +10% Monolithic Ceramic
10µF Tantalum (minimum) *
C21
C23
C26
Flt 1
Flt 2
IFT 1
L1
L2
X1
R9
R19
R10
R11
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
10kΩ +1%
10kΩ +1%
16kΩ +5% 1/4W Carbon Composition
2kΩ +1% 1/4W Metal Film
44.545MHz Crystal ICM4712701
0.8µH nominal
Toko 292CNS–T1038Z
455kHz (Ce = 180pF) Toko RMC–2A6597H
Ceramic Filter Murata SFG455A3 or equiv
Ceramic Filter Murata SFG455A3 or equiv
0.1µF +10% Monolithic Ceramic
147–160nH Coilcraft UNI–10/142–04J08S
C1
C2
C5
C6
C7
C8
C9
C10
C12
C14
C15
C17
C18
Automatic Test Circuit Component List
1.3k
51.7
71.5
96.5
32.8
51.5
R14 5kΩ +1%
R9
DEEMPHASIS
FILTER
SW11
R10
R11
C12
C25 100nF +10% Monolithic Ceramic
R17 2.4kΩ +5% 1/4W Carbon Composition
Figure 1. SA607 45MHz Test Circuit (Relays as shown)
R19
16k
R18
3.3k
C26
R18 3.3kΩ +5% 1/4W Carbon Composition
C27 2.2µF
FREQ
CHECK
*NOTE: This value can be reduced when a battery is the power source.
RSSI
IF
AMP
MIXER QUAD
20 19 18 17 16 15 14 13 12 11
10987654321
OSCILLATOR
VREG
+
–+
–
LIMITER
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 7
RSSI
IF
AMP
MIXER QUAD
20 19 18 17 16 15 14 13 12 11
10987654321
AUDIO
C14
IFT1
C10
C9
C8
C7
C6 X1
L2
VCC
C5
C2
C1
L1
C18
C15
C17
FLT2
SW8
C23 C21
R17
2.4k
FLT1
51pF NPO Ceramic
220pF NPO Ceramic
5-30pF NPO Ceramic
1nF Ceramic
10.0pF NPO Ceramic
10pF NPO Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
2.2µF
100nF +10% Monolithic Ceramic
10µF Tantalum (minimum) *
C21
C23
C26
Flt 1
Flt 2
IFT 1
L1
L2
X1
R9
R19
R10
R11
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
10kΩ +1%
8.2kΩ +1%
16kΩ +5% 1/4W Carbon Composition
2kΩ +1% 1/4W Metal Film
44.545MHz Crystal Hy-Q
1.2µH Coilcraft 1008CS–122
Ceramic Filter Murata SFG455A3 or equiv
Ceramic Filter Murata SFG455A3 or equiv
0.1µF +10% Monolithic Ceramic
C1
C2
C5
C6
C7
C8
C9
C10
C12
C14
C15
C17
C18
Product Board SA608D/DK Component List
OSCILLATOR
R14 10kΩ +1%
VREG
+
–+
–
LIMITER
C25 100nF +10% Monolithic Ceramic
R17 2.4kΩ +5% 1/4W Carbon Composition
Figure 2. SA608 45MHz Test Circuit (Relays as shown)
R19
11k
R18
3.3k
C26
R18 3.3kΩ +5% 1/4W Carbon Composition
C27 2.2µF
OUT
RSSI
OUTPUT FREQ
CHECK
C12
*NOTE: This value can be reduced when a battery is the power source.
C19
390pF
C19 390pF +10% Monolithic Ceramic
0.33µH TOKO SCB–1320Z
330µH TOKO 303LN–1130
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 8
RF GENERATOR SA608 DEMO-BOARD
C–MESSAGE
HP339A DISTORTION
ANALYZER
SCOPE
DC VOLTMETER
VCC (+3)
45MHz
DE-EMPHASIS
FILTER
RSSI AUDIO
Figure 3. SA608 Application Circuit Test Set Up
NOTES:
1. C-message: The C-message and de-emphasis filter combination has a peak gain of 10 for accurate measurements. Without the gain, the
measurements may be affected by the noise of the scope and HP339 analyzer. The de-emphasis filter has a fixed -6dB/Octave slope be-
tween 300Hz and 3kHz.
2. Ceramic filters: The ceramic filters can be 30kHz SFG455A3s made by Murata which have 30kHz IF bandwidth (they come in blue), or
16kHz CFU455Ds, also made by Murata (they come in black). All of our specifications and testing are done with the more wideband filter.
3. RF generator: Set your RF generator at 45.000MHz, use a 1kHz modulation frequency and a 6kHz deviation if you use 16kHz filters, or
8kHz if you use 30kHz filters.
4. Sensitivity: The measured typical sensitivity for 12dB SINAD should be 0.35µV or –116dBm at the RF input.
5. Layout: The layout is very critical in the performance of the receiver. We highly recommend our demo board layout.
6. RSSI: The smallest RSSI voltage (i.e., when no RF input is present and the input is terminated) is a measure of the quality of the layout and
design. If the lowest RSSI voltage is 500mV or higher, it means the receiver is in regenerative mode. In that case, the receiver sensitivity
will be worse than expected.
7. Supply bypass and shielding: All of the inductors, the quad tank, and their shield must be grounded. A 10-15µF or higher value tantalum
capacitor on the supply line is essential. A low frequency ESR screening test on this capacitor will ensure consistent good sensitivity in pro-
duction. A 0.1µF bypass capacitor on the supply pin, and grounded near the 44.545MHz oscillator improves sensitivity by 2-3dB.
8. R5 can be used to bias the oscillator transistor at a higher current for operation above 45MHz. Recommended value is 22kΩ, but should not
be below 10kΩ.
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 9
6
5
4
3
2
–55 –35 –15 5 25 45 65 85 105 125
VCC = 2.7V
VCC = 3V
VCC = 5V
VCC = 7V
Figure 4. ICC vs Temperature
mA
°C
Figure 5. Third Order Intercept Point vs Supply Voltage
Temperature (°C)
50 INPUT INTERCEPT POINT (dBm)Ω
–8.0
–8.5
–9.0
–9.5
–10.0
–10.5
–11.0
–11.5
–12.0
–12.5
–13.0
–13.5
–14.0
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80
7V
3V
2.7V
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 10
Figure 6. Mixer Noise Figure vs Supply Voltage
TEMPERATURE (°C)
NOISE FIGURE
8.00
7.75
7.50
7.25
7.00
6.75
6.50
6.25
6.00
5.75
5.50
5.25
5.00
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80
2.7V
3V
7.0V
Figure 7. Conversion Gain vs Supply Voltage
TEMPERATURE (°C)
18.00
17.75
17.50
17.25
17.00
16.75
16.50
16.25
16.00
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80
2.7V
3V
7.0V
CONVERSION GAIN (dB)
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 11
Figure 8. Mixer Third Order Intercept and Compression
20
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–66 –56 –46 –36 –26 –16 –6 4 14 24 34
FUND PRODUCT 3rd ORDER PRODUCT
*50Ω INPUT
IF OUTPUT POWER (–dBm)
RF* INPUT LEVEL (dBm)
RF = 45MHz
IF = 455kHz
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 12
DECIBELS (dB)
5
–125 –115 –105 –95 –85 –75 –65 –55 –45 –35 –25
RF LEVEL (dBm)
Figure 9. Sensitivity vs RF Level (–40°C)
0
–5
–10
–15
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
VCC = 3V
RF = 45MHz
DEVIATION = ±8kHz
AUDIO LEVEL = 52.5mVRMS
AUDIO
THD + NOISE
AM REJECTION
NOISE
DECIBELS (dB)
5
–125 –115 –105 –95 –85 –75 –65 –55 –45 –35 –25
RF LEVEL (dBm)
Figure 10. Sensitivity vs RF Level (+25°C)
0
–5
–10
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
VCC = 3V
RF = 45MHz
DEVIATION = ±8kHz
AUDIO LEVEL = 58.5mVRMS
AUDIO
THD + NOISE
AM REJECTION
NOISE
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 13
DECIBELS (dB)
5
–125 –115 –105 –95 –85 –75 –65 –55 –45 –35 –25
RF LEVEL (dBm)
Figure 11. Sensitivity vs RF Level (Temperature 85°C)
0
–5
–10
–15
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
VCC = 3V
RF = 45MHz
DEVIATION = ±8kHz
AUDIO LEVEL = 63.5mVRMS
AUDIO
THD + NOISE
AM REJECTION
NOISE
DECIBELS (dB)
5
0
–5
–10
–15
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
VCC = 3V
RF = 45MHz
DEVIATION = ±8kHz
AUDIO LEVEL = +58.6mVRMS
Figure 12. Relative Audio Level, Distortion, AM Rejection and Noise vs Temperature
AUDIO
DISTORTION
AM REJECTION
NOISE
RF LEVEL = –45dBm
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 14
2.400
2.000
1.600
1.200
0.800
0.400
0.000
–95 –85 –75 –65 –55 –45 –35 –25 –15 –5 5
Figure 13. RSSI (455kHz IF @ 3V)
IF LEVEL (dBm)
+85°C
–40°C
ROOM
VOLTAGE (V)
VOLTAGE (V)
2.1
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
–125 –115 –105 –95 –85 –75 –65 –55 –45 –35 –25
RF LEVEL (dBm)
+85°C
+27°C
–40°C
Figure 14. RSSI vs RF Level and Temperature - VCC = 3V
Philips Semiconductors RF Communications Products Product specification
SA608Low voltage high performance mixer FM IF system
November 3, 1992 15
300
–55 –35 –15 5 25 45 65 85 105 125
VCC = 2.7V
VCC = 3V
VCC = 5V
VCC = 7V
Figure 15. Audio Output vs Temperature
250
200
150
100
50
0
mVRMS
V
°C
