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參數(shù)資料
| 型號(hào)： | ZXF36L01 |
| 廠商： | Zetex Semiconductor |
| 英文描述： | VARIABLE Q FILTER |
| 中文描述： | 變量Q濾波器 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大小： | 832K |
| 代理商： | ZXF36L01 |
FILTERING HIGHER FREQUENCIES USING
THE MIXER
Frequencies above 150 kHz cannot be filtered directly;
themixerenablesthenotchpassfiltertofunctionupto
700kHz.
The signal to be filtered is mixed with another
frequency (local oscillator), chosen so that the
difference (intermediate) frequency equals the filter’s
centre frequency, fo. The local oscillator signal
waveform can be of any shape (sine, square, etc.) but
must be approximately 50% duty cycle.
Example
Input frequency = 300 kHz, Local Oscillator (LO)
frequency = 250 kHz,
Output (IF) Frequency = 50 kHz.
Ifthebandwidthofthe50kHzfilterwere1kHz,thefilter’sQ
factor would be:
50/1 = 50.
The bandwidth of the filter is still 1 kHz when 300 kHz is
applied to the mixer’s input, but now the Q factor is:
300/1 = 300.
The mixer provides a Q factor improvement equal to the
ratiooftheinputfrequencyandtheintermediatefrequency.
The effective centre frequency can also be externally
controlled by changing the LO frequency. This allows
frequency tuning, trimming or sweeping while employing
fixed resistors and capacitors for the filter.
AstheLOsignalcanbeasquarewave,thisallows‘fo’tobe
controlled using a microcontroller or microprocessor.
MIXER CONFIGURATION WITH NOTCH PASS FILTER
(with attenuating skirts)
The mixer can only be used with this filter configuration, as
the other types have 0dB stop bands. The mixer output
‘MXO’ becomes the input of the filter.
As the gain of the notch filter changes with Q, the output of
the mixer must be attenuated by some factor (VR
Atten
). This
will prevent the filter from being overdriven and allows the
user to set the required output level.
Note:
As the local oscillator input, LO has a low input
impedance (60
), it will often be necessary to increase it
for driving circuitry. As the input voltage required is low
(around 5 mV pk-pk min.), a series resistor ‘R
Mixer
’ can be
inserted. A value of 1 k
per 100mV (pk) oscillator signal
input will be suitable.
ZXF36L01
ISSUE 3 - JANUARY 2002
9
5V
Output Signal
Input Signal
Oscillator Input (LO)
V
DD
FI2
FO
MXI
LO
BI
BG
N/C
N/C
N/C
PD
V
DD
R
R
C
C
Rf
Ri
1
24
5V
R
Mixer
100nF
100nF
100nF
100nF
VR
Atten
V
SS
FI1
C1
RC1
R2
BI
MXO
RC2
GP1
GP2
GP3
V
SS
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ZXF36L01EVB | ZXF36L01 EVALUATION BOARD |
| ZXF36L01W24 | VARIABLE Q FILTER |
| ZXF36L01W24TC | VARIABLE Q FILTER |
| ZXFBF04 | 4 Channel Buffer Device |
| ZXFBF04N14 | 4 Channel Buffer Device |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ZXF36L01EVB | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:ZXF36L01 EVALUATION BOARD |
| ZXF36L01W24 | 功能描述:信號(hào)調(diào)節(jié) Variable Q Filter RoHS:否 制造商:EPCOS 產(chǎn)品:Duplexers 頻率:782 MHz, 751 MHz 頻率范圍: 電壓額定值: 帶寬: 阻抗:50 Ohms 端接類型:SMD/SMT 封裝 / 箱體:2.5 mm x 2 mm 工作溫度范圍:- 30 C to + 85 C 封裝:Reel |
| ZXF36L01W24TC | 功能描述:信號(hào)調(diào)節(jié) Variable Q Filter RoHS:否 制造商:EPCOS 產(chǎn)品:Duplexers 頻率:782 MHz, 751 MHz 頻率范圍: 電壓額定值: 帶寬: 阻抗:50 Ohms 端接類型:SMD/SMT 封裝 / 箱體:2.5 mm x 2 mm 工作溫度范圍:- 30 C to + 85 C 封裝:Reel |
| ZXF36L01W24TR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:IC-SM-VARIABLE Q FILTER |
| ZXFBF04 | 制造商:ZETEX 制造商全稱:ZETEX 功能描述:4 Channel Buffer Device |
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