Motorola MC3362 Application Note

MOTOROLA
SEMICONDUCTOR
APPLICATION NOTE
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by AN98Q/D
AN980
VHF Narrowband FM Receiver Design
Using the MC3362 and the MC3363
Dual Conversion Receivers
Prepared by: Jon Stiiwell
Ricky
Ng
Motorola has developed a series of low power narrow-
band FM dual conversion receivers in monolithic silicon
integrated circuits. The MC3362 and the MC3363 are man¬
ufactured in Motorola's MOSAIC process technology.
This process develops NPN transistors with fy = 4 +
GHz, which allows the MC3362 and the MC3363 to have
excellent very high frequency (VHF) operation with low
power drain. They are ideal for application in cordless
phones, narrowband voice and data receivers, CB and
amateur band radios, radio frequency (RF) security
devices and other applications through 200 MHz.
Features of the MC3362/3 Receiver ICs:
• Broadband RF input frequency capability (to 200 MHz
using internal oscillator, over 450 MHz using external
oscillator)
• Single supply operation from V(X = 2 to 7 Vdc
• Low power consumption dec = 3 mA typical at
Vqc
= 2 Vdc)
• Internally biased NPN RF transistor amplifier (MC3363)
• Complete dual conversion circuitry — first mixer and
oscillator included
• First local oscillator (LO) includes buffered output and
varactor diode to allow phase locked-loop (PLL) fre¬
quency synthesis for multichannel operation.
• Buffered second local oscillator output available for
PLL reference input (MC3362)
• Multistage limiter and quadrature detection circuitry
included
• RSSI (Received Signal Strength Indicator) with Carrier
Detect logic included
• Built-in data slicing comparator detects zero crossings
of FSK data transmission
• Inverting operational amplifier included for audio mut¬
ing or active filtering (MC3363)
SCOPE
This application note contains functional descriptions
and applications information pertaining to the various
functional blocks of the MC3362/3 receiver circuits. Four
receiver application circuits are shown. A single channel
receiver and a 10 channel frequency synthesized receiver
designed for the 49 MHz cordless telephone band are
shown. A 256 channel "2 Meter" (144-148 MHz) amateur
band receiver is also shown, including an appropriate PLL
frequency synthesizer design to control the receiver's
local oscillator. Finally, a low cost application featuring
the MC3362 as a single chip manually tunable 162 MHz
weatherband receiver is shown. A directory of external
component manufacturers is included as an appendix.
COMPARISON OF THE MC3362 AND THE MC3363
Figures 1A and IB show the system block diagrams of
MC3362 and MC3363, respectively. The MC3362 and the
MC3363 are made from the same die, but a final metal
mask difference allows different features to be made
available on each. Data pertaining to the common func¬
tional blocks are identical on both circuits.
The MC3363 is a complete VHF dual conversion FM
receiver including RF amplifier, two mixers and oscilla¬
tors, limiting IF amplifier and quadrature detection cir¬
cuitry, received signal strength indicator (RSSI) circuitry,
squelch circuitry and a data shaping comparator for
detecting FM frequency shift keyed (FSK) data transmis¬
sions. Receivers using the MC3363 alone can achieve
better than 0.3 /uV input sensitivity for 12 dB SINAD, from
a 50 O source. The MC3363 comes in a 28-lead plastic
wide SOIC package only.
The MC3362 is optimized for cordless telephone appli¬
cations and as such does not contain the RF preamplifier
or squelch circuitry. In addition, the second local oscil¬
lator contains a buffered output so that it can serve as
the system frequency reference in applications where a
10.240 MHz or 10.245 MHz reference is needed. In gen¬
eral, the MC3362 can be substituted for the MC3363
where:
• A receiver with sensitivity of 0.7 /i.V at the input for
12 dB SINAD is adequate.
• An external RF preamplifier with AGC is desired (such
as MOSFET's 3N211 and MPF211).
• Receiver squelch is not needed.
• Surface mount technology cannot be used. The
MC3362 is available in two 24-lead plastic packages
(DIP and wide SOIC surface mount).
MOSAIC is a trademark of Motorola. Inc.
(M) MOTOROLA
©MOTOROLA INC.. 1988