MC3356
Wideband FSK Receiver
The MC3356 includes Oscillator, Mixer, Limiting IF Amplifier, Quadrature
Detector, Audio Buffer, Squelch, Meter Drive, Squelch Status output, and
Data Shaper comparator. The MC3356 is designed for use in digital data
communciations equipment.
• Data Rates up to 500 kilobaud
•
DEVICE ON LIFETIME BUY
•
•
WIDEBAND
FSK
RECEIVER
Excellent Sensitivity: – 3 dB Limiting Sensitivity
Excellent Sensitivity: 30 µVrms @ 100 MHz
Highly Versatile, Full Function Device, yet Few External Parts are
Required
Down Converter Can be Used Independently — Similar to NE602
SEMICONDUCTOR
TECHNICAL DATA
P SUFFIX
PLASTIC PACKAGE
CASE 738
DW SUFFIX
PLASTIC PACKAGE
CASE 751D
(SO–20L)
Figure 1. Representative Block Diagram
RF
VCC
PIN CONNECTIONS
RF
Ground
1
20
2
19
3
18
OSC
4
Mixer
Data Shaping
Comparator
+
5
Ceramic
Filter
6
7
–
17
RF Ground 1
Data
Output
VCC
14
8
13
9
12
10
19 Ground
OSC Collector 3
18 Data Output
Squelch
Status
Hysteresis
RF VCC 4
17 + Comparator
Mixer Output 5
16 – Comparator
IF VCC 6
15 Squelch Status
Squelch
Adjust
(Meter)
Limiter Input 7
14 Squelch Control
Limiter Bias 8
Buffer
Limiter
20 RF Input
OSC Emitter 2
Ground
16
15
Comparator –
+
Meter Current
RF
Input
13 Buffered Output
Limiter Bias 9
12 Demodulator
Filter
11
Quad Bias 10
ORDERING INFORMATION
Quadrature Detector
Tank
Device
MC3356DW
VCC
MC3356P
Operating
Temperature Range
TA = – 40 to +85°C
© Motorola, Inc. 1996
MOTOROLA WIRELESS SEMICONDUCTOR
SOLUTIONS – RF AND IF DEVICE DATA
11 Quad Input
Package
SO–20L
Plastic DIP
Rev 0
1
LAST ORDER 15JAN02 LAST SHIP 27DEC02
Order this document by MC3356/D
MC3356
Figure 3. Output Components of Signal,
Noise, and Distortion
10
700
S+N+D
fO = 100 MHz
fm = 1.0 kHz
∆f = ± 75 kHz
–10
–20
–30
N+D
–40
N
–50
DEVICE ON LIFETIME BUY
METER CURRENT, PIN 14 (µA)
RELATIVE OUTPUT (dB)
0
–60
0.01
0.1
1.0
10
600
500
400
300
200
100
0
0.010
0.1
INPUT (mVrms)
1.0
10
PIN 20 INPUT (mVrms)
100
1000
GENERAL DESCRIPTION
This device is intended for single and double conversion
VHF receiver systems, primarily for FSK data transmission
up to 500 K baud (250 kHz). It contains an oscillator, mixer,
limiting IF, quadrature detector, signal strength meter drive,
and data shaping amplifier.
The oscillator is a common base Colpitts type which can
be crystal controlled, as shown in Figure 1, or L–C controlled
as shown in the other figures. At higher VCC, it has been
operated as high as 200 MHz. A mixer/oscillator voltage gain
of 2 up to approximately 150 MHz, is readily achievable.
The mixer functions well from an input signal of
10 µVrms, below which the squelch is unpredictable, up to
about 10 mVrms, before any evidence of overload.
Operation up to 1.0 Vrms input is permitted, but non–linearity
of the meter output is incurred, and some oscillator pulling is
suspected. The AM rejection above 10 mVrms is degraded.
The limiting IF is a high frequency type, capable of being
operated up to 50 MHz. It is expected to be used at 10.7 MHz
in most cases, due to the availability of standard ceramic
resonators. The quadrature detector is internally coupled to
the IF, and a 5.0 pF quadrature capacitor is internally
provided. The –3dB limiting sensitivity of the IF itself is
approximately 50 µV (at Pin 7), and the IF can accept signals
up to 1.0 Vrms without distortion or change of detector
quiescent dc level.
The IF is unusual in that each of the last 5 stages of the
6 state limiter contains a signal strength sensitive, current
sinking device. These are parallel connected and buffered to
produce a signal strength meter drive which is fairly linear for
IF input signals of 10 µV to 100 mVrms (see Figure 4).
A simple squelch arrangement is provided whereby the
meter current flowing through the meter load resistance flips
a comparator at about 0.8 Vdc above ground. The signal
strength at which this occurs can be adjusted by changing
the meter load resistor. The comparator (+) input and output
are available to permit control of hysteresis. Good positive
MOTOROLA WIRELESS SEMICONDUCTOR
SOLUTIONS – RF AND IF DEVICE DATA
action can be obtained for IF input signals of above 30
µVrms. The 130 kΩ resistor shown in the test circuit provides
a small amount of hysteresis. Its connection between the
3.3 k resistor to ground and the 3.0 k pot, permits adjustment
of squelch level without changing the amount of hysteresis.
The squelch is internally connected to both the
quadrature detector and the data shaper. The quadrature
detector output, when squelched, goes to a dc level
approximately equal to the zero signal level unsquelched.
The squelch causes the data shaper to produce a high (VCC)
output.
The data shaper is a complete ‘‘floating’’ comparator,
with back to back diodes across its inputs. The output of the
quadrature detector can be fed directly to either input of this
amplifier to produce an output that is either at VCC or VEE,
depending upon the received frequency. The impedance of
the biasing can be varied to produce an amplifier which
“follows” frequency detuning to some degree, to prevent data
pulse width changes.
When the data shaper is driven directly from the
demodulator output, Pin 13, there may be distortion at Pin 13
due to the diodes, but this is not important in the data
application. A useful note in relating high/low input frequency
to logic state: low IF frequency corresponds to low
demodulator output. If the oscillator is above the incoming
RF frequency, then high RF frequency will produce a logic
low (input to (+) input of Data Shaper as shown in Figures 1
and 2).
APPLICATION NOTES
The MC3356 is a high frequency/high gain receiver that
requires following certain layout techniques in designing a
stable circuit configuration. The objective is to minimize or
eliminate, if possible, any unwanted feedback.
3
LAST ORDER 15JAN02 LAST SHIP 27DEC02
Figure 4. Meter Current versus Signal Input
