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參數(shù)資料
| 型號： | MAX2754 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 1.2GHz VCO with Linear Modulation Input |
| 中文描述： | 1.2GHz VCO，帶有線性調(diào)制輸入 |
| 文件頁數(shù)： | 5/8頁 |
| 文件大?。?/td> | 175K |
| 代理商： | MAX2754 |
Detailed Description
Oscillator
The MAX2754 VCO is implemented as an LC oscillator
topology, integrating all of the tank components on-
chip. This fully monolithic approach provides an
extremely easy-to-use VCO, equivalent to a VCO mod-
ule. The frequency is controlled by a voltage applied to
the TUNE pin. The VCO core uses a differential topolo-
gy to provide a stable frequency versus supply voltage
and improve the immunity to load variations. In addi-
tion, there is a buffer amplifier following the oscillator
core to provide added isolation from load and supply
variations and to boost the output power.
Linear Modulation
The linear modulation input offers a means to directly
FM modulate the VCO with a controlled amount of fre-
quency deviation for a given input voltage deviation.
The unique technique maintains a consistent modula-
tion gain (df/dV
MOD
) across the entire frequency tuning
range of the part, enabling accurate FM modulation
derived solely from the filtered NRZ
“
data
”
stream (the
modulation voltage input).
The modulation input is single-ended and centered
about +1.4V. The linear modulation full-scale range is
±1V around this point, for a +0.4V to +2.4V input volt-
age range. A very important point to note is that the
sign of the modulation gain is negative. A positive
change in V
MOD
results in a negative change in oscilla-
tion frequency. This convention for the modulation gain
is due to the practical implementation of the internal lin-
earizing circuitry. This gain inversion must be consid-
ered when designing the analog voltage interface that
drives the linear modulation input. The easiest way to
handle this is to invert the logic polarity of the modula-
tion data three-state output buffer (TX data output).
Where it is impossible to invert the data-stream logic
polarity, an external inverter and three-state buffer
would be required. These devices are offered in small
single-logic gates in SC-79 style packages from various
manufacturers (e.g., Fairchild
—
Tiny Logic, On
Semiconductor, or Rohm).
Figure 1 illustrates the frequency versus V
MOD
charac-
teristic of the modulation input. Note the negative slope
of the curve, df
MOD
/dV
MOD
< 0, where f
MOD
= f
OUT
-
f
NOM
.
Output Buffer
The oscillator signal from the core drives an output
buffer amplifier. The amplifier is internally matched to
50
including an on-chip DC-blocking capacitor. The
return loss can be improved to a minimum of 12dB over
1145MHz to 1250MHz by adding a 2.5nH series induc-
tor and a 3.0pF shunt capacitor. The output buffer has
a ground connection separate from the oscillator core
to minimize load-pulling effects. The amplifier boosts
the oscillator signal to a level suitable for driving most
RF mixers.
M
1.2GHz VCO with Linear
Modulation Input
_______________________________________________________________________________________
5
Pin Description
PIN
NAME
FUNCTION
1
VREG
Capacitor Connection to the On-Chip Linear Regulator Output. Connect a 330nF capacitor to ground.
2
TUNE
Oscillator Frequency Tuning-Voltage Input. High-impedance input with a voltage range of +0.4V (low
frequency) to +2.4V (high frequency).
3
GND1
Ground Connection for the Oscillator Core. Requires a low-inductance connection to the circuit-
board ground plane.
4
MOD
Linear Modulation Input. High-impedance CMOS input with a voltage range of +0.4V to +2.4V.
5
SHDN
Shutdown Input. Drive logic low to place the device in shutdown mode. Drive logic high for normal
operation.
6
GND2
Ground Connection for Output-Buffered Amplifier, Linear Modulation Interface, and Biasing.
Requires a low-inductance connection to the circuit-board ground plane.
7
OUT
Buffered Oscillator Output. Incorporates an internal DC-blocking capacitor. OUT is internally
matched to 50
.
8
V
CC
Supply Voltage Connection. Requires external RF bypass capacitor to ground for low noise and low
spurious content performance from the oscillator. Bypass with a 330pF capacitor to ground.
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| MAX2754EUA | 功能描述:VCO振蕩器 1.2Ghz VCO w/Linear Modulation Input RoHS:否 制造商:Exar 封裝 / 箱體:SOIC-14 頻率:300 kHz 負載電容: 封裝:Reel 電源電壓:4.5 V to 20 V 尺寸:4 mm W x 8.75 mm L x 1.75 mm H 最小工作溫度:0 C 最大工作溫度:+ 70 C |
| MAX2754EUA+ | 功能描述:VCO振蕩器 1.2Ghz VCO w/Linear Modulation Input RoHS:否 制造商:Exar 封裝 / 箱體:SOIC-14 頻率:300 kHz 負載電容: 封裝:Reel 電源電壓:4.5 V to 20 V 尺寸:4 mm W x 8.75 mm L x 1.75 mm H 最小工作溫度:0 C 最大工作溫度:+ 70 C |
| MAX2754EUA+T | 功能描述:VCO振蕩器 1.2Ghz VCO w/Linear Modulation Input RoHS:否 制造商:Exar 封裝 / 箱體:SOIC-14 頻率:300 kHz 負載電容: 封裝:Reel 電源電壓:4.5 V to 20 V 尺寸:4 mm W x 8.75 mm L x 1.75 mm H 最小工作溫度:0 C 最大工作溫度:+ 70 C |
| MAX2754EUA-T | 功能描述:VCO振蕩器 MAX2754 Eval Kit RoHS:否 制造商:Exar 封裝 / 箱體:SOIC-14 頻率:300 kHz 負載電容: 封裝:Reel 電源電壓:4.5 V to 20 V 尺寸:4 mm W x 8.75 mm L x 1.75 mm H 最小工作溫度:0 C 最大工作溫度:+ 70 C |
| MAX2754EVKIT | 功能描述:時鐘和定時器開發(fā)工具 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Evaluation Modules 類型:Clock Conditioners 工具用于評估:LMK04100B 頻率:122.8 MHz 工作電源電壓:3.3 V |
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