CLASS E & F AMPLIEFER
Leader: Ralph Harvey Villacarlos
Members: Mark Alfred Taban
Edsel Jay Taghap
Jayno Ben Tapungot
Ruel Urdaneta
Noven Villaber
Class E
Amplifier
• Class E amplifier, composed only a single
transistor. Both bipolar and MOSFET can be
used.
• In this class, MOSFET is preferred to use
because of its low drive requirements.
Figure 1: Typical Class E RF amplifier
The carrier, which may initially be a sine wave, is
applied to a shaping circuit that effectively
converts it to a square wave.
The carrier is usually frequency-modulated. The
square wave carrier signal is then applied to the
base of the class E bipolar power amplifier
Figure 1: Typical Class E RF amplifier
Class E can in practicality, achieve very
high efficiencies. Also contrary to Class D.
there are no short-circuited currents that
result in efficiency losses. This design also
requires careful selection of the typical
shunt-resonant circuit to reduce the high
harmonic levels.
Figure 2: Generic Configuration for Class B, C, and E Amplifiers
Figure 3: is an example of the typical drain
voltage and current waveforms for this
class. In this instance the unique
characteristic is that the drain voltage is
driven well into the mode region
Figure 3: Class-E Amplifier Waveforms
Class E Theory of Operation
Figure 4: Simplified Drain Resonant Circuit
In addition to understanding the timing for the
drain resonant circuit is also very important.
Figure 5 illustrates the problems that can occur
when this circuit is improperly designed.
Figure 5: Drain Voltage Waveforms
In figure 5.
1st waveform - both power and efficiency performance degrade rapidly
- there will be a reduction in output power from the ideal value,
where the drain resonant frequency is too high.
2nd waveform - both voltage and current waveforms perform non-overlapping.
3rd waveform - Overlapping voltage and current waveforms mean that a
significant amount of power will be wasted in the output device.
Examples of
Class E
Amplifiers
Some examples of
Class E Amplifiers
• Wide-Band 40-m HF-Band
Class-E PA
This amplifier features a 60%
fractional bandwidth at 7MHz, 90%
peak drain efficiency, and 50 W of
output power. It was designed by
means of the admittance-synthesis
technique, providing proper load for
class-E nominal operation at the
fundamental and harmonics
Some examples of
Class E Amplifiers
• Wide-Band
Class-E PA
VHF-Band
a wide-band class-E amplifier
designed for the mid-VHF (FM
broadcast) band. The amplifier
features a 40% fractional bandwidth
at 100 MHz, a 90% peak drain
efficiency, and 150 W of output
power. It is also designed by means
of
the
admittance-synthesis
technique
Some examples of
Class E Amplifiers
• 1-kW Continuous Wave Class-E
PA
a class-E amplifier designed by IXYS
Colorado for the 27.12-MHz ISM
frequency . The circuit is a class-E
amplifier demo board (also designed by
IXYS Colorado) with 1,000-W continuous
wave (CW) output power and efficiency
better than 86% into a 50-Ω load. This is
an excellent board to use for
understanding the capabilities of IXYS
MOSFETs for this application and learn
about the possibilities of high-power
class-E amplifiers in the HF range.
Other examples of Class E Amplifiers
Applications of
E Amplifiers
• In class E amplifier the parasitic drain depletion-region capacitance can be
resonated with the inductive load when configured. Because of this. Class E
can. in practicality. achieve very high efficiencies.
• Used to ideally achieve nearly 100% efficiency
• The class-E amplifier is a highly efficient tuned switching power amplifier used
at radio frequencies.
• Class-E Power Amplifiers for Wireless Transceivers
• The class E power amplifier is attractive in MHz range wireless power transfer
(WPT) application
• Used in designing switching-mode tuned power amplifiers
Class F
Amplifiers
• Class F amplifiers contains an additional resonant
network in the collector or drain circuit.
• It boost both efficiency and output by using
harmonic resonators in the output network to
shape the output waveform into a square waves.
• It is capable of high efficiencies of more than 90%
if infinite harmonic tuning is used
Power Amplifier Class Comparison
Ideal class F RF power amplifier circuit with turned circuit
Ideal Wave form of Class F Amplifier
Types of Class F
Amplifiers
1. Class F Power Amplifier
2. Inverse Class F Power Amplifier
Class F Power Amplifier
The Class F RF Power Amplifiers utilize
multiple harmonic resonators in the output
network to shape the drain to source voltage
(VDS) such that the transistor switching loss is
reduced and the efficiency is increased. The
drain current flows when the drain to source
voltage is low, and the drain to source voltage
is high when the drain current is zero.
Class F Power Amplifier
In this type of amplifier with odd harmonics,
the drain to source voltage contains only odd
harmonics and the drain current contains only
even harmonics. The drain to source voltage
VDS of class F amplifiers with odd harmonics
is symmetrical for the lower and upper half of
the cycle.
Class F Power Amplifier
On the other hand amplifier with even
harmonics, the drain to source voltage
contains only even harmonics and the drain
current contains only odd harmonics.
Therefore the load network represents an
open circuit at even harmonics and a short
circuit at odd harmonics.
Class F Power Amplifier
Ideal class F RF power amplifier circuit with tuned
circuit.
Inverse Class F Power Amplifier
In inverse class F amplifier, the even
harmonics is tuning instead of the odd in order
to shape the drain current to be a square and
the drain to source voltage will be a sine
wave form.
The efficiency of this amplifier is better due to
the higher V peak and has the less dc power
dissipation with the same RF power output.
Inverse Class F Power Amplifier
Ideal Inverse class F RF power amplifier circuit with
tuned circuit.
Applications of
F Amplifiers
• The F amplifiers are used to increase the
efficiency and output by the harmonic
resonators.
• Class F RF power amplifiers are applied in
modern portable and base station transmitters
due to their high-efficiency operation.
• Class F amplifiers are used to boosts up PAE.
• Class F amplifier are good for devices with
limited breakdown voltage.
• Class F RF Power Amplifiers are used to
shape the drain to source voltage.
THANK YOU 