Browse Prior Art Database

RF HIGH POWER SWITCH WITH REVERSE BIASED PIN-DIODES

IP.com Disclosure Number: IPCOM000007278D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2002-Mar-11
Document File: 2 page(s) / 84K

Publishing Venue

Motorola

Related People

Bernhard Hammes: AUTHOR

Abstract

Rfswitches often consist of PIN-diodes which are in a high impedance state while high rfpower is applied. Above a certain rf power level, the PIN- diode's change to a lower rf impedance range increases the dissipation loss and might further destroy the component. To prevent an impedance decrease caused by rf power the device has to be reverse biased. A conservative solution of selecting the bias is to avoid the rf magnitude to exceed the dc bias voltage. This requires high negative dc volt- ages which are costly and not always available, espe- cially in mobile or portable equipment. A so called conditional save operation can be achieved with a lower bias voltage only as high as the self-generated dc voltage ofthe PIN-diode. This voltage level which is dependent on the device type and the rf power level often still exceeds the available dc voltages.

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MOTOROLA Technical Developments Volumk 23 October 1994

RF HIGH POWER SWITCH ~ WITH REVERSE BIASED PIN-DIODES

by Bernhard Hammes

  Rfswitches often consist of PIN-diodes which are in a high impedance state while high rfpower is applied. Above a certain rf power level, the PIN- diode's change to a lower rf impedance range increases the dissipation loss and might further destroy the component. To prevent an impedance decrease caused by rf power the device has to be reverse biased. A conservative solution of selecting the bias is to avoid the rf magnitude to exceed the dc bias voltage. This requires high negative dc volt- ages which are costly and not always available, espe- cially in mobile or portable equipment. A so called conditional save operation can be achieved with a lower bias voltage only as high as the self-generated dc voltage ofthe PIN-diode. This voltage level which is dependent on the device type and the rf power level often still exceeds the available dc voltages.

  The rfpower can be &pled fiorn the high power path via resistive or capacitive divider or by use of a directional coupler. Ho&ever the capacitive divider shows some advantages: It is practically lossless, space and costsaving. The capacitor connected to the high power path can be realiied as two printed areas on a double layer pc board,~ to avoid expensive capaci- tors with high voltage capability. The other capaci- tor should be discrete to easily adjust the bias volt- age. To increase the generated dc voltage, the coupled rfvoltage can be transformed to a higher level before rectifying.

  The dc voltage...