F2923 Constant Impedance K|z| SP2T RF Switch
Created: Dec 18, 2015
No description available.
This design of RF switch is used in multitude of wireless applications. It features constant impedance K|Z| during switching transition with 0.48dB at 2GHz very low insertion loss. It can cover a broad frequency range from 300kHz to 800MHz with an industry leading isolation at 2GHz and excellent linearity. The RF1/RF2 to RF_Com isolation is 74dB at 2GHz. It has 1-pin or 2-pin device control option. The supply voltage supports 1.8V and logic voltage is 3.3V at 127uA low DC current. It can operate within temperature range -55°C to +105°C.
The design is not as rigid as the standard FR4 in which the connection to the board must be taking care to avoid physical damage. The external supply is in the voltage range of 3.1V to 3.5V which power supply output must be disabled on this setup. To setup the part for two-pin logic control connects a 2-pin shunt from pin 3 (ModeCTL) to pin 4 (GND) on connector J8. For one pin logic control leave J8 pin 3 open. An on-board pull-up resistor R10 will connect the ModeCTL pin to Vcc to provide the logic high for one pin control. It also includes 2 pull-up resistors (R7, R8) to Vcc to provide logic high for CTL1 and CTL2 respectively. Installing a 2-pin shunt from pin 7 (CTL1) to pin 8 (GND) of J8 will provide a logic low for manual control of the CTL1 pin. Placing a 2-pin shunt from pin 9 (CTL2) to pin 10 (GND) of J8 will result in logic low for the CTL2 pin. Resistor R6 along with the 1.8VSEL, 1.8VSEL2, and LogicCTL pins are not used on the F2923 EVKIT. In using external control logic, connect a 2-pin shunt from pin 3 (ModeCTL) to pin 4 (GND) on connector J8 in order to setup the part for two-pin logic control. For one pin control leave pin 3 (ModeCTL) of J8 open. In this configuration the ModeCTL pin will be pulled up to Vcc on the PCB through resistor R10. In turning ON procedure, set these to logic low and enable the VCC supply if controlling CTL1 and CTL2 with external logic. Note that external control logic should not be applied without VCC being applied first. For manual logic control the J8 connector CTL1 and CTL2 pins can be grounded to a neighboring ground for a logic low or left open for logic high. In turning OFF procedure, set them to a logic low if using external control logic for CTL1, CTL2 while the VCC supply should be disabled.
The design is applicable to repeaters and E11 systems and base station 2G, 3G, 4G. The KZ minimizes LO pulling in VCOs and reduces phase and amplitude variations in distribution networks. It is also ideal for dynamic switching/selection between two or more amplifiers while avoiding damage to upstream/downstream sensitive devices such as PAs and ADCs.