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Maxim > Design Support > Technical Documents > Application Notes > Wireless and RF > APP 530
Keywords: rf, rfdesign, rfic, vco, rfics, rf design, rf ics
APPLICATION NOTE 530
VCO Tank Design for the MAX2310
Sep 30, 2002
Abstract: This application note presents various voltage-controlled oscillator (VCO) designs for popular IF
frequencies of 85MHz, 190MHz, and 210MHz. These designs reduce the number of iterations required
for optimized results. Analysis can be accomplished with a simple spreadsheet program.
Additional Information:
Wireless Product Line Page
Quick View Data Sheet for the MAX2306/MAX2308/MAX2309
Quick View Data Sheet for the
MAX2310/MAX2312/MAX2314/MAX2316
Applications Technical Support
Introduction
This application note presents various voltage-controlled oscillator
(VCO) designs for popular IF frequencies of 85MHz, 190MHz, and
210MHz. These designs reduce the number of iterations required for optimized results. Analysis can be
accomplished with a simple spreadsheet program.
VCO Design
Figure 2 shows the differential tank circuit used for the MAX2310 IF VCO. For analysis purposes, the
tank circuit must be reduced to an equivalent simplified model. Figure 1 depicts the basic VCO model.
The frequency of oscillation can be characterized by EQN1:
EQN1
f
osc
= frequency of oscillation
L = inductance of the coil in the tank circuit
C
int
= internal capacitance of the MAX2310 tank port
C
t
= total equivalent capacitance of the tank circuit
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