FAST SWITCHING, REMOTE CONTROLLED SATCOM LOW NOISE AMPLIFIER
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-30
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.