SA676 [NXP]
Low-voltage mixer FM IF system; 低压混频器FM IF系统
| 型号： | SA676 |
| 厂家： | 
NXP |
| 描述： | Low-voltage mixer FM IF system |
| 文件： | 总8页 (文件大小：106K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
DESCRIPTION
PIN CONFIGURATION
The SA676 is a low-voltage 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 SA676
is available in a 20-pin SSOP (shrink small outline package).
DK Package
1
2
RF IN+
20 MIXER OUT
19
IF AMP DECOUPLING
RF IN– DECOUPLING
18 IF AMP IN
17
3
4
OSC
OUT
The SA676 was designed for cordless telephone applications in
which efficient and economic integrated solutions are required and
yet high performance is desirable. Although the product is not
targeted to meet the stringent specifications of high performance
cellular equipment, it will exceed the needs for analog cordless
phones. The minimal amount of external components and absence
of any external adjustments makes for a very economical solution.
IF AMP DECOUPLING
OSC
IN
16 IF AMP OUT
15 GND
RSSI OUT
5
6
7
V
CC
14 LIMITER IN
AUDIO FEEDBACK
AUDIO OUT
13
8
9
LIMITER DECOUPLING
12
RSSI FEEDBACK
LIMITER DECOUPLING
FEATURES
11 LIMITER OUT
QUADRATURE IN 10
• Low power consumption: 3.5mA typical at 3V
SR00514
• Mixer input to >100MHz
Figure 1. Pin Configuration
• Mixer conversion power gain of 17dB at 45MHz
• XTAL oscillator effective to 100MHz (L.C. oscillator or external
• Audio output internal op amp
oscillator can be used at higher frequencies)
• RSSI output internal op amp
• 102dB of IF Amp/Limiter gain
• Internal op amps with rail-to-rail outputs
• 2MHz IF amp/limiter small signal bandwidth
• ESD protection: Human Body Model 2kV
• Temperature compensated logarithmic Received Signal Strength
Robot Model 200V
Indicator (RSSI) with a 70dB dynamic range
• Low external component count; suitable for crystal/ceramic/LC
APPLICATION
• Cordless phones
filters
ORDERING INFORMATION
DESCRIPTION
TEMPERATURE RANGE
ORDER CODE
SA676DK
DWG #
20-Pin Plastic Shrink Small Outline Package (Surface-mount)
-40 to +85°C
SOT266-1
BLOCK DIAGRAM
20
19
18
17
16
15
14
13
12
11
IF
AMP
LIMITER
RSSI
MIXER
QUAD
OSCILLATOR
–
+
+
–
V
REG
AUDIO
E
B
1
2
3
4
5
6
7
8
9
10
SR00515
Figure 2. Block Diagram
6–129
1993 Dec 15
853-1726 11659
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
RATING
7
UNITS
V
V
CC
Single supply voltage
T
Storage temperature range
–65 to +150
–40 to +85
117
°C
STG
T
Operating ambient temperature range
Thermal impedance DK package
°C
A
θ
°C/W
JA
DC ELECTRICAL CHARACTERISTICS
V
CC
= +3V, T = 25°C; unless otherwise stated.
A
LIMITS
SYMBOL
PARAMETER
TEST CONDITIONS
SA676
TYP
UNITS
MAX
MIN
V
Power supply voltage range
DC current drain
2.7
7.0
5.0
V
CC
I
3.5
mA
CC
AC ELECTRICAL CHARACTERISTICS
T = 25°C; V = +3V, unless otherwise stated. RF frequency = 45MHz; +14.5dBV RF input step-up; IF frequency = 455kHz; R17 = 2.4kΩ
A
CC
and R18 = 3.3kΩ; RF level = –45dBm; FM modulation = 1kHz with ±5kHz peak deviation. Audio output with de-emphasis filter and C-message
weighted filter. Test circuit Figure 3. The parameters listed below are tested using automatic test equipment to assure consistent electrical
characteristics. 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
UNITS
MIN
TYP
MAX
Mixer/Osc section (ext LO = 220mV
)
RMS
f
Input signal frequency
100
100
7.0
MHz
MHz
dB
IN
f
Crystal oscillator frequency
Noise figure at 45MHz
OSC
Third–order input intercept point (50Ω
source)
f1 = 45.0; f2 = 45.06MHz
–10
dBm
Input RF level = –52dBm
Matched 14.5dBV step–up
50Ω source
Conversion power gain
10
17
+2.5
8
dB
dB
kΩ
pF
kΩ
RF input resistance
RF input capacitance
Mixer output resistance
Single–ended input
3.0
1.5
4.0
(Pin 20)
1.25
IF section
IF amp gain
50Ω source
44
58
dB
dB
dB
mV
dB
dB
dB
V
Limiter gain
50Ω source
AM rejection
30% AM 1kHz
Gain of two
50
Audio level
60
120
17
SINAD sensitivity
Total harmonic distortion
IF level –110dBm
THD
S/N
–55
60
Signal–to–noise ratio
No modulation for noise
IF level = –110dBm
IF level = –50dBm
1
IF RSSI output, R = 2kΩ
0.5
1.7
70
.90
2.2
9
V
RSSI range
dB
kΩ
kΩ
kΩ
kΩ
IF input impedance
IF output impedance
Limiter input impedance
Limiter output impedance
Limiter output voltage
Pin 18
Pin 16
Pin 14
Pin 11
Pin 11
1.3
1.3
1.5
0.3
1.5
0.3
130
mV
RMS
6–130
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
AC ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL
PARAMETER
TEST CONDITIONS
LIMITS
TYP
UNITS
MAX
MIN
RF/IF section (int LO)
System SINAD sensitivity
RF level = –114dBm
12
dB
NOTE:
1. The generator source impedance is 50Ω, but the SA676 input impedance at Pin 18 is 1500Ω. As a result, IF level refers to the actual signal
that enters the SA676 input (Pin 18) which is about 21dB less than the “available power” at the generator.
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.
CIRCUIT DESCRIPTION
The SA676 is an IF signal processing system suitable for second IF
systems with input frequency as high as 100MHz. The bandwidth of
the IF amplifier and limiter is at least 2MHz with 90dB of gain. The
gain/bandwidth distribution is optimized for 455kHz, 1.5kΩ source
applications. The overall system is well-suited to battery operation
as well as and high quality products of all types.
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 input stage is a Gilbert cell mixer with oscillator. Typical mixer
characteristics include a noise figure of 7.0dB, conversion gain of
17dB, and input third-order intercept of –10dBm. The oscillator will
operate in excess of 100MHz in L/C tank configurations. Hartley or
Colpitts circuits can be used up to 100MHz for xtal configurations.
The demodulated output of the quadrature drives an internal op
amp. This op amp can be configured as a unity gain buffer, or for
simultaneous gain, filtering, and 2nd-order temperature
compensation if needed. It can drive an AC load as low as 10kΩ
with a rail-to-rail output.
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 44dB of gain and 5.5MHz
bandwidth. The IF limiter has 58dB 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
A log signal strength indicator completes the circuitry. The output
range is greater than 70dB and is temperature compensated. This
signal drives an internal op amp. The op amp is capable of
rail-to-rail output. It can be used for gain, filtering, or 2nd-order
temperature compensation of the RSSI, if needed.
NOTE: dB(v) = 20log V
/V
OUT IN
6–131
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
C26
R18
3.3k
R17
2.4k
C15
FLT1
C23
FLT2
C18
C21
C17
20
19
18
17
16
15
14
13
12
11
IF
AMP
LIMITER
MIXER
RSSI
QUAD
OSCILLATOR
+ –
– +
V
REG
1
2
3
4
5
6
7
8
9
10
R11
10k
C1
C2
C9
C12
C8
R10
10k
L1
C27
C7
2.2µF
C10
C5
R19
11k
IFT1
L2
45MHz
INPUT
X1
C6
C19
390pF
C14
RSSI
OUTPUT
AUDIO
V
CC
SA676DK Demoboard
Application Component List
C1 51pF NPO Ceramic
C2 220pF NPO Ceramic
C23
C26
C27
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
2.2µF Tantalum
C5
100nF +10% Monolithic Ceramic
FLT 1 Ceramic Filter Murata SFG455A3 or equiv
FLT 2 Ceramic Filter Murata SFG455A3 or equiv
C6 5-30pF trim cap
C7 1nF Ceramic
IFT 1
L1
L2
330µH TOKO 303LN-1130
330nH Coilcraft UNI-10/142-04J08S
0.8µH nominal TOKO 292CNS-T1038Z
C8 10.0pF NPO Ceramic
C9
100nF +10% Monolithic Ceramic
C10
C12
C14
10µF Tantalum (minimum) *
2.2µF +10% Tantalum
100nF +10% Monolithic Ceramic
X1 44.545MHz Crystal ICM4712701
R5 Not Used in Application Board (see Note 8, pg 8)
R10
R11
R17
R18
R19
C15 10pF NPO Ceramic
8.2k +5% 1/4W Carbon Composition
10k +5% 1/4W Carbon Composition
2.4k +5% 1/4W Carbon Composition
3.3k +5% 1/4W Carbon Composition
11k +5% 1/4W Carbon Composition
C17
C18
100nF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
C19
C21
390pF +10% Monolithic Ceramic
100nF +10% Monolithic Ceramic
* NOTE: This value can be reduced when a battery is the power source.
SR00516
Figure 3. SA676 45MHz Application Circuit
6–132
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
RF GENERATOR
45MHz
SA676 DEMOBOARD
RSSI AUDIO
V
(+3)
CC
DE-EMPHASIS
FILTER
DC VOLTMETER
C–MESSAGE
HP339A DISTORTION
ANALYZER
SCOPE
SR00517
Figure 4. SA676 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 HP339A analyzer. The de-emphasis filter has a fixed -6dB/Octave slope
between 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 specifications and testing are done with the 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 0.45µV or –114dBm 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
production. 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.
6–133
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
mA
6
V
= 7V
CC
5
4
3
2
V
= 5V
CC
I
(mA)
CC
V
= 3V
CC
V
= 2.7V
CC
°C
–55
–35
–15
5
25
45
65
85
105
125
TEMPERATURE (°C)
SR00518
Figure 5. I vs Temperature and Supply Voltage
CC
18.00
17.75
17.50
17.25
17.00
16.75
16.50
16.25
16.00
2.7V
3V
7.0V
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
TEMPERATURE (°C)
SR00519
Figure 6. Conversion Gain vs Temperature and Supply Voltage
6–134
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
20
10
0
RF = 45MHz
IF = 455kHz
–10
–20
–30
3rd ORDER PRODUCT
FUND PRODUCT
–40
–50
–60
–70
–80
–66
*50Ω INPUT
–56
–46
–36
–26
–16
–6
4
14
24
34
RF* INPUT LEVEL (dBm)
SR00520
Figure 7. Mixer Third Order Intercept and Compression
5
0
AUDIO
–5
–10
V
= 3V
CC
RF = 45MHz
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
DEVIATION = ±5kHz
AUDIO LEVEL = 117.6mV
RMS
AM REJECTION
THD + NOISE
NOISE
–125
–115
–105
–95
–85
–75
RF LEVEL (dBm)
–65
–55
–45
–35
–25
SR00521
Figure 8. Sensitivity vs RF Level (+25°C)
6–135
1993 Dec 15
Philips Semiconductors
Product specification
Low-voltage mixer FM IF system
SA676
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
+85°C
+27°C
–40°C
–125
–115
–105
–95
–85
–75
–65
–55
–45
RF LEVEL (dBm)
SR00522
Figure 9. RSSI vs RF Level and Temperature - V = 3V
CC
V
300
250
200
150
100
50
V
= 7V
CC
V
V
= 5V
CC
CC
= 3V
V
= 2.7V
CC
°C
0
–55
–35
–15
5
25
45
65
85
105
125
SR00523
Figure 10. Audio Output vs Temperature and Supply Voltage
6–136
1993 Dec 15
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