Constant impedance marks out SPDT RF switch's performance

November 26, 2015 // By Graham Prophet
IDT's F2923 provides constant impedance on all ports during switching transitions without compromising isolation, linearity or insertion loss.

Positioned as the first single-pole, double-throw (SPDT) RF switch featuring IDT'S KZ constant impedance technology, The IDT F2923 is a low insertion loss SPDT absorptive RF switch designed for a RF applications including base stations (2G, 3G, 4G, 5G), wireless backhaul, CATV, and portable handhelds.

The KZ feature controls all port impedances when switching between RF ports, preserving the return loss. Standard switches without KZ create a large voltage standing wave ratio (VSWR) transient when switching RF paths because the impedance of the switch is not well controlled during the switching event. A VSWR transient can degrade system performance and reduce reliability. Benefits of KZ in different dynamic or 'hot switching' scenarios include:

- minimising switched Tx/Rx synthesiser pulling and recovery time in TDD systems

- avoiding damage and error-inducing transients when switching between two RF elements such as PAs, drivers and LNAs.

- minimising transient amplitude and phase error on the unswitched path(s) when switching a path of a distribution network such as a 3 dB coupler or 4-way splitter

In addition to KZ technology, the device delivers:

- Insertion loss of 0.48 dB at 2 GHz

- IIP3 greater than 66 dBm @ 2 GHz

- Isolation of 74 dB at 2 GHz

Covering a frequency range from 300 kHz to 8000 MHz, IDT's KZ technology ensures the device delivers near-constant impedance (VSWR < 1.4:1 compared to 9:1 for standard switches) when switching from one RF port to another while not compromising isolation, linearity, or insertion loss. The F2923 uses a single positive supply voltage of 3.3V and supports standard 1.8V and 3.3V control logic levels. It occupies a 4 x 4 mm 20-TQFN package.

IDT; www.idt.com