Browse Prior Art Database

FAST SWITCHING, REMOTE CONTROLLED SATCOM LOW NOISE AMPLIFIER

IP.com Disclosure Number: IPCOM000009540D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-30
Document File: 5 page(s) / 143K

Publishing Venue

Motorola

Related People

Steve Plager: AUTHOR

Abstract

This paper addresses the problem of switching watts of RF power with less than 0.5 dB insertion (bypassing) a remotely located LNA (low noise loss with a transition time of less than 100 usec. A amplifier) used for Satellite Communications typical satellite terminal installation is as shown in (Satcom) in the band of 225 to 400 MHz. The Figure 1. bypass switch must be capable of handling 250 ANTENNA Fig. 1 Typical DAMA Satellite Terminal Installation 0 Momlvla. 1°C. 1999 224 September 1999 0 M MOTOROLA Technical Developments A simplified block diagram is shown in Figure CNTL port, If the control voltage is higher than 19 2. The LNA unit receives a control voltage via the VDC, the LNA is switched to receive mode, the center conductor of the RF coax cable at the control ANTENNA port is routed to the band pass filter (CNTL) port. If the control voltage is between 14 (BPF) input and the CNTL port is routed to the VDC and 19 VDC the LNA is switched to bypass LNA output. mode and the ANTENNA port is routed to the 0 0 CNTL ANTENNA BPF Fig. 2 Simplified LNA Block Diagram 0 hkmnda. Inc. ,999 225 September 1999 0 M MO3VROLA Technical Developments The switching of the LNA described above is performed with pin diodes in a tuned microstrip cir- cuit. A detailed block diagram is shown in Figure 3.

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Page 1 of 5

Developments Technical 0 M M-ROLA = -

FAST SWITCHING, REMOTE CONTROLLED SATCOM LOW NOISE AMPLIFIER

by Steve Plager

  This paper addresses the problem of switching watts of RF power with less than 0.5 dB insertion (bypassing) a remotely located LNA (low noise loss with a transition time of less than 100 usec. A amplifier) used for Satellite Communications typical satellite terminal installation is as shown in (Satcom) in the band of 225 to 400 MHz. The Figure 1.
bypass switch must be capable of handling 250

ANTENNA

Fig. 1 Typical DAMA Satellite Terminal Installation

0 Momlvla. 1°C. 1999 224 September 1999

[This page contains 14 pictures or other non-text objects]

Page 2 of 5

Developments Technical 0 M MOTOROLA

A simplified block diagram is shown in Figure CNTL port, If the control voltage is higher than 19
2. The LNA unit receives a control voltage via the VDC, the LNA is switched to receive mode, the center conductor of the RF coax cable at the control ANTENNA port is routed to the band pass filter (CNTL) port. If the control voltage is between 14 (BPF) input and the CNTL port is routed to the VDC and 19 VDC the LNA is switched to bypass LNA output.
mode and the ANTENNA port is routed to the

0 0

CNTL ANTENNA

BPF

Fig. 2 Simplified LNA Block Diagram

0 hkmnda. Inc. ,999 225 September 1999

[This page contains 14 pictures or other non-text objects]

Page 3 of 5

Developments Technical 0 M MO3VROLA -

  The switching of the LNA described above is performed with pin diodes in a tuned microstrip cir- cuit. A detailed block diagram is shown in Figure 3.

  In bypass mode, all diodes are forward biased and the LNA is isolated (from transmitter high power RF) by quarter wave microstrip lines TL2 and TL5 and shunt diodes D3 and D6. TLl is a quarter wave line which in combination with TL2 and TL5 provide low insertion loss between the

CNTL and ANTENNA ports in the 225 MHz to 400 MHz band.

  In receive mode, all diodes are zero biased. Lines TL2-TL3 and TL4-TL.5 form a half wave transformer at 280 MHz that match the ANTENNA and CNTL ports to the BPF input and LNA output respectively. Diodes Dl and D2 and line TLI iso- late the ANTENNA and CNTL ports to prevent LNA oscillation.

ANTENNA

TL3 LNA INPUT
.__

;tohq _ ;rohmri !NA OUTPUT?

114

A

A

114

MHz 260MHr $

"D6

280

/ DS

-I- I

Fig. 3 LNA Block Diagram

0 Mommla.l"c. 1999 226 September 1999

[This page contains 15 pictures or other non-text objects]

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MOTOROLA Technical De...