AN4016 Datasheet, PDF (1/17 Pages) STMicroelectronics – 2 kW PPA for ISM applications

AN4016
Application note
2 kW PPA for ISM applications
Introduction
STMicoelectronics has recently introduced a new generation of high voltage DMOS
products housed in STAC^® air cavity packages and capable of delivering an output power of
up to 1.2 kW for industrial, scientific, and medical applications such as 1.5 T and 3 T
magnetic resonance imaging (MRI). This new air-cavity technology now enables lower
thermal resistance, lower weight, and reduced cost compared to devices in ceramic
packages.
In this application note we report on the design of a 2 kW-100 V, 123 MHz Class AB peak
power amplifier (PPA) for 3 Tesla MRI applications. It almost doubles the output power of
previous amplifiers using MOSFET transistors in standard ceramic packages. The design
techniques and construction practices are described in enough detail to permit duplication
of the amplifier. The devices used in this amplifier are two STAC4932B N-channel
MOSFETs in a push-pull configuration capable of 1.2 kW each, under pulse conditions, and
housed in the STAC244B, a bolt-down air cavity package.
The design goals for the amplifier are:
■ Frequency: 123 MHz
■ Supply voltage: 100 V
■ Pulse conditions: 1 msec – 10%
■ Output power: > 2 kW
■ Gain: > 19 dB
■ Efficiency: > 60%
Figure 1. STEVAL-IMR002V1
December 2011
Doc ID 022523 Rev 1
AM10219V1
1/17
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