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參數(shù)資料
| 型號： | MC3335 |
| 廠商： | Motorola, Inc. |
| 英文描述： | Low Power Narrowband FM Receiver |
| 中文描述： | 低功耗窄帶調(diào)頻接收機 |
| 文件頁數(shù)： | 4/6頁 |
| 文件大?。?/td> | 129K |
| 代理商： | MC3335 |
MC3335
4
MOTOROLA ANALOG IC DEVICE DATA
CIRCUIT DESCRIPTION
The MC3335 is a complete FM narrowband receiver from
antenna input to audio preamp output. The low voltage dual
conversion design yields low power drain, excellent
sensitivity and good image rejection in narrowband voice and
data link applications.
In the typical application diagram, the first mixer amplifies
the signal and converts the RF input to 10.7 MHz. This IF
signal is filtered externally and fed into the second mixer,
which further amplifies the signal and converts it to a 455 kHz
IF signal. After external bandpass filtering, the low IF is fed
into the limiting amplifier and detection circuitry. The audio is
recovered using a conventional quadrature detector.
Twice–IF filtering is provided internally.
The input signal level is monitored by meter drive circuitry
which detects the amount of limiting in the limiting amplifier.
The voltage at the meter drive pin determines the state of the
carrier detect output which is active low.
APPLICATIONS INFORMATION
The first local oscillator can be run using a free running LC
tank, as a VCO using PLL synthesis, or driven from an
external crystal oscillator. At higher VCC values (6.0 to
7.0 V), it has been run to 170 MHz. The second local
oscillator is a common base Colpitts type which is typically
run at 10.245 MHz under crystal control.
The mixers are doubly balanced to reduce spurious
responses. The first and second mixers have conversion
gains of 18 dB and 22 dB (typical), respectively. Mixer gain is
stable with respect to supply voltage. For both conversions,
the mixer impedances and pin layout are designed to allow
the user to employ low cost, readily available ceramic filters.
Overall sensitivity is shown in Figure 5. The input level for
20 dB (S + N)/N is 1.3
μ
V using the two–pole post–detection
filter as demonstrated.
Following the first mixer, a 10.7 MHz ceramic bandpass
filter is recommended. The 10.7 MHz filtered signal is then
fed into one second mixer input pin, the other input pin being
connected to VCC. Pin 5 (VCC) is treated as a common point
for emitter–driven signals.
The 455 kHz IF is typically filtered using a ceramic
bandpass filter, then fed into the limiter input pin. The limiter
has 10
μ
V sensitivity for –3.0 dB limiting, flat to 1.0 MHz.
The output of the limiter is internally connected to the
quadrature detector, including a quadrature capacitor. A
parallel LC tank is needed externally from Pin 11 to VCC.
A 39 k
shunt resistance is included which determines the
peak separation of the quadrature detector; a smaller value
will increase the spacing and linearity but decrease
recovered audio and sensitivity.
A data shaping circuit is available and can be coupled to
the recovered audio output of Pin 12. The circuit is a
comparator which is designed to detect zero crossings of
FSK modulation. Data rates of up to 35000 baud are
detectable using the typical application. Hysteresis is
available by connecting a high–valued resistor from Pin 13 to
Pin 14. Values below 120 k
are not recommended as the
input signal cannot overcome the hysteresis.
The meter drive circuitry detects input signal level by
monitoring the limiting of the limiting amplifier stages.
Figure 2 shows the unloaded current at Pin 9 versus input
power. The meter drive current can be used directly (RSSI)
or can be used to trip the carrier detect circuit at a specified
input power. To do this, pick an RF trip level in dBm. Read the
corresponding current from Figure 2 and pick a resistor such
that:
R9 = 0.64 Vdc / I9
Hysteresis is available by connecting a high–valued
resistor RH between Pin 9 and 10. The formula is:
Hysteresis = VCC/(RH x 10–7) dB
相關(guān)PDF資料 |
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| MC3335DW | Low Power Narrowband FM Receiver |
| MC3335P | Low Power Narrowband FM Receiver |
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| MC33362 | Isolated Flyback Switching Regulator with 9V Output |
| MC33362DW | Isolated Flyback Switching Regulator with 9V Output |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| MC33350SN-7T1 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MC33351ADTB-001 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MC33351DTB-001 | 制造商:ON Semiconductor 功能描述: |
| MC33362DW | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 ANA HI VOLT OFFLN SW REG RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MC33362DWG | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 ANA HI VOLT OFFLN SW REG RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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