Varactor-Tuned Oscillators
Technical Data
VTO-8000 Series
Features
isolates the oscillator from
Pin Configuration
TO-8V
• 600 MHz to 10.85 GHz
Coverage
variations in load impedance for
low frequency pulling, allows the
oscillator to run lighty-loaded for
low phase noise content and
provides +10 dBm of minimum
output power over the full tuning
range. The VTO-8000 Series
varactor-tuned oscillators are
packaged in TO-8 transistor cans
for simple installation in a
GROUND
• Fast Tuning
3
1
+V
TUNE
RF OUT
• +7 to +13 dBm Output
Power
2
4
• ±1.5 dB Output Flatness
+DC
VOLTAGE
CASE GROUND
• Hermetic Thin-film
Construction
conventional 50-ohm micro-
stripline PC board. They are ideal
for most compact, lightweight
commercial and military equip-
ment designs. Test fixturing is
also available for lab bench test
applications. See the “Test
Fixtures for TO-8 Packages”
section for additional information
and outlines.
Description
Agilent Technologies’s VTO-8000
Series oscillators use a silicon
transistor chip as a negative
resistance oscillator. The oscilla-
tion frequency is determined by a
silicon abrupt varactor diode
acting as a voltage-variable
necessary RF filtering action yet
as low as possible to maximize
∆V/∆T characteristics for excel-
lent tuning speeds. Used in a
phase locked loop PLL circuit, a
VTO provides a receiver LO with
stability equivalent to the refer-
ence oscillator (usually crystal
controlled), yet variable in
discrete steps or continuously
depending on the PLL
capacitor in a thin-film micro-
stripline resonator. This provides
extremely fast tuning speed,
limited primarily by the internal
impedance of the user-supplied
voltage driver. Fast settling is
another feature of the Agilent
VTO-8000 Series oscillators.
Typical settling times for the
VTO-8090 are <200 kHz within one
microsecond while the VTO-8950
settles to <2 MHz within two
microseconds referenced to ten
milliseconds. The VTO-8850
combines a bipolar transistor
oscillator with a GaAs FET buffer
stage. This GaAs FET buffer
Applications
Frequency agile systems, such as
digitally controlled receivers and
active jamming transmitters often
use externally linearized
configuration.
Another important aspect of VTOs
used in an LO application is their
power vs. frequency flatness
(±1.5 dB). This assures that once a
receiver mixer is biased for best
dynamic range the local oscillator
drive will remain constant
throughout the tuning range
without complex leveling
varactor-tuned oscillators.
Agilent oscillators are monotonic
making external linearization
easy using analog (opamp) or
digital (EPROM) linearizing
techniques. The Agilent VTO
Series has been designed with a
tuning input bypass capacitance
which is sufficient to provide the
circuitry.