RF Class E Power Amplifiers Test
Automation Design Project
Sponsored by: SPAWAR
Mentor: Jeremy D. Popp
Currently, the setup, testing, optimization, and
data collection on class E power amplifier (PA)
circuits is a manual, time consuming and costly
Testing RFIC Power Amplifiers is approaching
10 percent of per-unit cost.
Minimizing test time by combining today’s
intelligent instruments, and software we can
increase testing throughput, thus generating a
substantially cost effective high-production
What Is An Amplifier?
An amplifier is a device used for increasing the
power of a signal.
Power is drawn from a power supply and used
to output an enlarged version of the input signal.
Properties to look for from an
we have to look at the ratio of the output
signal to the input.
we have to know how much wide our signal
output has to be.
3. Power delivered
we have to make sure that most of the input power
delivered to the load.
Properties to look for ………
4. Drain/collector efficiency
Minimize any loss across BJT.
Properties to look for……
Find the minimum size as much as possible.
Minimize any lose in the form of heat &
Class A Amplifier
Amplifies over entire input cycle
Biased in Active Linear Region
Very inefficient: always conducting, even if there is no
input signal (theoretical maximum of 50% obtainable
Cheap: require only a single active device
Class B Amplifier
Amplifies only half of the input signal cycle
Less power dissipated and wasted since amplifier
is switched off for half of the signal
Improved efficiency over Class A
Class B Push-Pull Configuration
In order to amplify entire signal “push-pull”
configuration must be used with two Class B amplifiers
Overall good efficiency but produces crossover
distortion at the middle join of the individual amplified
Class AB Amplifier
Similar to Class B, however a portion of the
signal beyond half of the signal is also amplified
in a non-linear region
When these non-linear amplified regions are
combined, crossover distortion is reduced
Class C Amplifier
Amplifies less than half of the input signal
Very high distortion of the output signal
Can be used for RF transmitters if tuned loads are
implemented which reduce the distortion
Class E Power Amplifier
Characteristics of operation
Employs a single transistor operated as a switch
rather than a current source
High power efficiency, >70 percent ( Ideally 100%),
through the use of a resonant output network
In optimum class E, the drain voltage drops to zero
and has zero slope just as the transistor turns ON.
Amplifier Topology &
Transistor Voltage and Current
Class E Amplifier Stage
One Transistor Topology
Transistor Current and
No simultaneous high
signals across transistor
Standard Equations for
the tank circuit
Q 1 Q 2.08
C 2 C1
Job Descriptions &
Class E test System Design
Software Application Design
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