On the other hand, in order to improve the linearity of Doherty power amplifier, one of the possible and simplified techniques is Composite Right/Left-Handed Transmission Lines (CRLH-TL) for its character of suppressing the second harmonic of the carrier amplifier
of the Doherty power amplifier.
At this time, the carrier amplifier
will be gradually saturated to keep a high efficiency while the peak amplifier provides the additional power required.
The advantage is that the carrier amplifier
amplifies only the average signal.
A conventional Doherty amplifier is composed of a carrier amplifier
and a peak amplifier.
2Doherty amplifier: An RF amplifier that consists of two types of amplifiers: a carrier amplifier
that is in continuous operation and a peak amplifier that supports the carrier amplifier
when the output power is high.
The fundamental Doherty architecture uses two parallel, equal power split transistors, a carrier amplifier
transistor for low level signals and a peaking amplifier transistor for high level signals.
A Doherty amplifier consists of a carrier amplifier
, a peak amplifier and a power combining network.
The new products satisfy the unique requirements of the Doherty amplifier architecture, in which a carrier amplifier
operating in Class AB mode is combined with a peaking amplifier operating in the higher-efficiency Class C mode.
The RF power transistors in Doherty amplifiers must provide excellent output impedance matching under both linear operating conditions in which the RF drive level of the carrier amplifier
is "backed-off" to ensure high linearity and efficiency, as well as during peak (maximum) signal conditions handled by the peaking amplifier.
The RF performances of the Doherty amplifier-I (a combination of a class B carrier amplifier
and a bias-tuned class C peaking amplifier) have been compared with those of a class B amplifier alone.
Our goal at Powerwave is to continue to leverage our core multi carrier amplifier
technology with innovative solutions that offer increasing levels of functionality for our customers.
The displayed amplifier shown is an 80 W IS-136 compliant PCS single carrier amplifier
operating from a wide range 20 to 30 V DC supply.