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High Reliability, High Isolation Single-Pole-Double-Throw RF switch

In telecommunications, ideal RF switches require low insertion loss, high isolation and linearity. The IDT F2912 is a single-pole-double throw RF switch capable of having low insertion of loss of 0.4dB at 1GHz and a RF1 to RF2 Isolation of 74dB at 1GHz with extended temperature of -55C to +125C making it highly reliable. In addition, this covers a broad frequency range from 300kHz to 8000MHz.

As a switch, it’s capable of 3 types of controls namely switch control, mode control, and logic control. The switch control includes (3 states and 2-pin control input) or (2 states and 1-pin control input). The 3 states and 2-pin control input operates like a XOR logic gate, if there is a high value input from the control pin either CTL1/CTL2 will trigger RF1 to RF Com if CTL1 is High or RF2 to RF Com if CTL2 is High. While the 2 states and 1-pin control input, a high value CTL2 will trigger RF2 to RF com and a low value CTL2 triggers RF1 to RF Com leaving the CTL1 a “don’t care”. The mode control use either (2-pin control: CTL1 and CTL2) or (1-pin control: CTL2). When RF1 and RF2 ports are both open (State 1), all 3 RF ports are terminated to an internal 50Ω termination resistor. When RF1 or RF2 port is open (State 2 or State 3 OFF condition), the open port is connected to an internal 50Ω termination resistor. When RF1 or RF2 port is closed (State 2 or State 3 ON condition), the closed port is connected to the RF Com port. The logic control operates using logic voltage 1.8V and 3.3V to operate logic CTL (pin18) VCC and GND respectively.

This circuit design can be applied more on base station 2G, 3G, 4G, portable wireless, repeaters and E911 systems, digital pre-distortion point to point infrastructure, public safety infrastructure WIMAX receivers and transmitters, military systems, JTRS radios, RFID handheld and portable readers, cable Infrastructure, wireless LAN, test/ ATE Equipment.

source: schematics.com/project/high-reliability-rf-switch/

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