of Specifications and Terms:
(The following definitions apply specifically to VCO'S unless otherwise
An oscillator may be considered a frequency converter, transforming
electrical energy at dc to some ac frequency, having a typically
sinusoidal waveform, and a transforming efficiency of less than
unity. Voltage Controlled Oscillator: An oscillator whose output
frequency is continuously tunable via the application of a control
In the frequency domain, an ideal carrier would appear as an infinitesimally
thin line, The typical carrier however, will have skirts whose amplitudes
generally follow 1 / f distribution with increasing video frequencies.
These skirts are the envelope of side bands due to modulations of
the carrier, and are both FM and AM in nature, random in both frequency
and amplitude, and are caused by various phenomena relating to the
physics of the particular oscillator, and are commonly referred
to as "NOISE". We specify phase noise as single sideband
power in relation to the fundamental RF output frequency, and measured
at various offset frequencies from the carrier, normalized to a
one hertz measuring bandwidth ( example -120dBc / Hz / 100KHz, offset
As specified in this catalog are the worst case amplitude of all
harmonically related outputs or signals relative to the carrier
(fundamental frequency) power. The measurement is normally expressed
in terms of dBc below the carrier (dBc); also referred to as "Harmonic
Spurious signals are any outputs in the spectrum of a source (VCO)
that are neither part of the carrier, not its harmonic and they
may be discreet or bands of frequencies. Modco VCO'S do not contain
any spurious outputs.
This could be defined as the change in frequency occurring within
a definite time frame beginning a particular time after an instantaneous
specified change in address (tuning voltage). Generally helpful
information to know for open loop fast tuning (EW) applications.
or Pushing Figure:
This refers to the maximum change in frequency and or power that
can be tolerated for a given change in the input voltage (Vcc).
This would be expressed in terms of "MHz per volt" for
frequency and "dB" for power.
or Pulling Figure:
This refers to the maximum change in frequency and or power tolerable
when a mismatch of specified magnitude at the output is rotated
through all phases (360 deg).
This is a measure of how much the frequency of the VCO changes
as a result of temperature
shifts, and is expressed in terms of "MHz / deg c".
Normally refers to the maximum amount of capacitance
located at the tuning voltage input terminal of a VCO.
The ratio of frequency change for a VCO to a change in tuning voltage
and is expressed in "MHz / volt".
The Frequency at which the Modulating Frequency Deviation decreases
to 0.707 of its DC value.
Standing Wave Ratio (VSWR):
The ratio of the maximum to minimum voltage present on a transmission
line, and normally due to load reflections from an unmatched VCO
(source) and load impedance.