Browse Prior Art Database

IMPROVED POWER HANDLING ELECTRONIC PF SWITCH

IP.com Disclosure Number: IPCOM000007277D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2002-Mar-11
Document File: 2 page(s) / 94K

Publishing Venue

Motorola

Related People

Tal Mor: AUTHOR [+2]

Abstract

Electronic RF switches, such as PIN diode or GaAs FET switches are essentially non linear devices. Thus their behavior is affected by the RF signal power. As RF power is increased, insertion loss and harmonic content are increased. Most commercial switches, therefore, specify 1dB compression point and 2nd and 3rd order intercept points. For a given device, improvement in these parameters is possi- ble by changing the switch drive. Thus, high power switches ohen require high current (PIN diode switches), or high voltage (FET switches).

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MOZOROLA Technical Developments Volume 23 October 1994

IMPROVED POWER HANDLING ELECTRONIC PF SWITCH

by Tal Mor and Eli Sasson

PROBLEM SOLVED BY THE INVENTION:

  Electronic RF switches, such as PIN diode or GaAs FET switches are essentially non linear devices. Thus their behavior is affected by the RF signal power. As RF power is increased, insertion loss and harmonic content are increased. Most commercial switches, therefore, specify 1dB compression point and 2nd and 3rd order intercept points. For a given device, improvement in these parameters is possi- ble by changing the switch drive. Thus, high power switches ohen require high current (PIN diode switches), or high voltage (FET switches).

(insertion loss or isolation). In such case the other parameter will improve.: It is therefore possible to trade off isolation for insertion loss or vice-versa, depending on switch configuration, while keeping the advantage ofimproved power handling.

  For example let us look into the classic PIN diode T/R switch. Figure 1 shows the switch without any transformation. Figure 2 shows the same switch with quarter wavelength transformers on all ports transforming 50 to 100 ohm. The quarter wavelength line between the two diodes is therefore changed to 100 ohm.

  Results indicate, as may be expected, that the transmitter to antenna path (~21) exhibits lower loss in the "on" position; but lower isolation in the "off' position. This may be expected in a series configuration.

  The antenna to receiver path (~32) employs a shunt configuration and therefore the effect is reversed, that is, using the transformation improves isolation, but degrades insertion loss.

DESCRIPTION OF THE INVENTION:

  The limiting factor in power handling is ohen not power but rather RF current or Rf voltage (in the case of PIN diode or FET sw...