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參數資料
| 型號： | TK14584M |
| 廠商： | TOKO INC |
| 元件分類： | 通信及網絡 |
| 英文描述： | FM IF IC |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDSO12 |
| 封裝： | PLASTIC, SSOP-12 |
| 文件頁數： | 16/20頁 |
| 文件大?。?/td> | 196K |
| 代理商： | TK14584M |
Page 16
January 2000 TOKO, Inc.
TK14584
The signal from the phase shifter is applied to the multiplier (in the dotted line) through emitter-follower stage QA. When
the phase shifter is connected between Pin 10 and Pin 9, note that the bias voltage to Pin 9 should be provided from an
external source because Pin 9 is only connected to the base of QA.
Because the base of QB (at the opposite side) is connected with the supply voltage, Pin 9 has to be biased with the
equivalent voltage.
Using an LC resonance circuit is not a problem (see Figure 5). However, when using a ceramic discriminator, it is necessary
to pay attention to bias. If there is a difference of the base voltages, the DC voltages of the multiplier do not balance. It
alters the DC zero point or worsens the distortion of demodulation output.
The Pin 9 input level should be saturated at the multiplier; if this level is lower, it is easy to disperse the modulation output.
Therefore, to have stable operation, Pin 9 should be higher than 100 mV
P-P
.
The following figures show examples of the phase shifter.
CIRCUIT DESCRIPTION (CONT.)
VCC
VCC
Delay
Line
VCC
Rz
Rz
Rz is the characteristic impedance
LC resonance circuit
ceramic discriminator
delay line
FIGURE 5 - EXAMPLES OF PHASE SHIFTERS
Establishing Demodulation Characteristics:
Generally, demodulation characteristics of FM detectors are determined by the external phase shifter. However, this
product has a unique function which can optionally establish the demodulation characteristics by the time constant of the
circuit parts after demodulation. The following explains this concept.
Figure 6 shows the internal equivalent circuit of the detector output stage.
The multiplier output current of the detector is converted to a voltage by the internal OP AMP. The characteristic of this
stage is determined by converting the current to voltage with resistor R
O
and the capacitor C
O
connected between Pin 7
and Pin 8 (see Figure 6).
In other words, the slope of the S-curve characteristic can be established optionally with resistor R
without changing the
constant of the phase shifter. The demodulated bandwidth can be established optionally by the time constant of this
external resistor R
and capacitor C
O
inside of a bandwidth of the IF-filter and phase shifter. Figure 7 shows an example
of this characteristic.
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相關代理商/技術參數 |
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|---|---|
| TK14584M/584 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:FM IF IC |
| TK14584MTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:FM IF IC |
| TK14588 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:FM IF IC |
| TK14588V | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:FM IF IC |
| TK14588V/14588 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:FM IF IC |
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