HMC784 - 10W RF SPDT Switch
LF to 4000 MHZ (4 GHZ), 30 dB Isolation,
15-40 nSec switching times
Very Low DC current - Good IMD3 (+60 dBm)
Based on the Hittite (now Analog Devices) HMC784 GaAs MMIC, this small PCB module is a complete RF SPDT (Single Pole Single Toggle) Switch for 50 ohm systems working from below 1 MHZ to more than 4000 MHZ with very low distortion at high power signal levels, up to + 40dBm (10 Watts), high transition speed and good isolation.
It has an RF input port and two output ports. Which output port is ON, is selected by a simple 2-bit interface and the port which is selected as OFF, becomes reflective short.
It draws under 20 uA at 8 VDC recommended for best transition speed, isolation and power handling, while still works from 3V DC with 0.5 uA current draw but with less isolation and power handling .
The PCB dimensions are only 33 x 38.5 mm and SMA edge connectors are used for all RF ports.
J4 is a 5-pin header and it is used to control the switch with its pin 1. It has a pull-up resistor (R3) and as is, the input port connects to the output J3. Applying a LOW at pin 1 the input port connects to J2 output port. Pin 5 is the Vdd input, 3 to 8 Volts will work, but for optimum results one should use 8V. Pins 2,3 and 4 are connected to the ground.
The 3 DC blocking capacitors are missing from the PCB module so they can be selected upon the application frequency range.
Also, in order not to distort the transmission line which connects J1 to the MMIC, a small wire link should be added to power the chip with DC power. It is shown at the middle photo below.
The KIT includes a high-quality ENIG FR4 PCB (33 x 38.5 mm) that comes with all SMD components factory pre-soldered except the DC blocking capacitors C1, C2 and C3 (0402 or 0603 size).
You need to solder one small wire on the bottom side of the PCB.
Three SMA female connectors with nuts and washers for pcb edge mounting are also supplied, unsoldered.