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參數(shù)資料
| 型號(hào)： | HT9015 |
| 廠商： | Holtek Semiconductor Inc. |
| 英文描述： | RF Single Chip for Cordless Phone |
| 中文描述： | 射頻單芯片無(wú)繩電話 |
| 文件頁(yè)數(shù)： | 15/23頁(yè) |
| 文件大?。?/td> | 206K |
| 代理商： | HT9015 |
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HT9015
15
April 10, 2000
Preliminary
Intermediate frequency (IF) decoder part
The figure below shows a simplified block dia-
gram for a double-conversion super heterodyne
FM receiver. Heterodyne means to mix two fre-
quencies together in a non linear device or to
translate one frequency to another using non
linear mixing. The super heterodyne receiver is
an improvement over other receiver in gain, se-
lectivity, and sensitivity characteristics.
The super heterodyne receiver is divided into
five parts:
RF section. Generally consists of a preselector
and an amplifier stage.
Mixer conversion section. Includes a ra-
dio-frequency oscillator stage (commonly
known as a local oscillator) and a mixer con-
version stage (commonly known as a fre-
quency detector) to produce the IF signal.
The IF section. Generally consists of a series of
IF amplifiers and bandpass filters and known
astheIFstrip.Mostofthereceivergainandse-
lectivity is achieved in the IF section.
The FM demodulator section: The quadrature
FM demodulator uses a 90 phase shift, a sin-
gle tuned circuit, and a product detector to de-
modulate the FM signals.
Theaudioamplifiersection.Theaudiosection
comprises several cascaded audio amplifiers
and one or more speakers. The number of am-
plifiers used depends on the audio signal
power desired.
Mixers
A Mixer is a non linear device whose purpose
is to convert radio frequencies (RF) to inter-
mediate frequency (IF) (RF-to-IF frequency
translation). In the frequency conversion pro-
cess, RF signals are combined with the local
oscillator frequency in a non linear device.
The output of the mixer contains an infinite
number of harmonic and cross-product fre-
quencies which include the sum and the dif-
ference between the desired RF carrier and
the local oscillator frequencies. The IF
band-pass filter are tuned to the different fre-
quencies. Therefore, the IF signal is filtered
out by the BPF. In the HT9015 the double con-
version method (Figure 4) is applied to pro-
duce the lower IF.
The first IF is a relatively high frequency
(10.7MHz), for good image-frequency rejec-
tion, while the second IF is a relatively low
frequency (455kHz) that allows the IF ampli-
fiers to have a relatively high gain and still
not be susceptible to oscillations.
* / &
1 + , 0 *
/
+ " " " +
"" + *
& & /
A B
" # & & /
A : + * B
" #
)
" #
- . + # + .
!&
&
*
! ++
!
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&
!
"
"
&
Figure 5 Intermediate frequency decoder block
" # & & /
A : + * B
+ , /
*
A $ 6 C D B
A > C D B
+ , /
" #
& & /
A
B
Figure 4 The illustration of mixers
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| HT9020B | Call Progress Tone Detector |
| HT9020 | Call Progress Tone Decoder & ABR Controller |
| HT9020A | Call Progress Tone Decoder & ABR Controller |
| HT9032 | Calling Line Identification Receiver |
| HT9033 | CAS Tone Detector |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HT9020 | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:Call Progress Tone Decoder & ABR Controller |
| HT9020A | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:Call Progress Tone Decoder & ABR Controller |
| HT9020A(18DIP) | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Subscriber Line Metering/Monitoring Circuit |
| HT9020A(18SOIC) | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Subscriber Line Metering/Monitoring Circuit |
| HT9020B | 制造商:HOLTEK 制造商全稱:Holtek Semiconductor Inc 功能描述:Call Progress Tone Decoder & ABR Controller |
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