Pin Diode Switch Ic

Rf switch with pin diodes circuit diagram.

Pin diode switch ic. Signal losses at the closed diode is negligible. There are many unique market applications such as the wireless communications market where new. A diode alone is not a complete and useful switch as it is only the core switching element. The wide intrinsic region is in contrast to an ordinary p n diode the wide intrinsic region makes the pin diode an inferior rectifier one typical.

The signal to noise ration of the receiver deteriorates somewhat up to 1 db. It is primarily a function of the thickness of the i region and thicker diodes can operate down to 1 mhz while thinner ones can function into. The pin diode switch can be used for antennas with impedances of from 50 ω up to 75 ω. A pin diode is a diode with a wide undoped intrinsic semiconductor region between a p type semiconductor and an n type semiconductor region.

Chapter 2 the common pin diode switch configurations are presented followed by sections comparing those features of pin diode switch designs for unique to high power microwave switches and high power lower frequency rf band switches. Connecting the switch driver control circuit to a pin diode such that it can turn diodes on and off by applying a forward or reverse bias is a challenging task. The p type and n type regions are typically heavily doped because they are used for ohmic contacts. Figure 5 shows a single pole double throw spdt rf switch and its bias circuit.

The operated diodes block the disconnected antennas by about 30 db. Thus a pin diode is a dc controlled high frequency resistor and if no dc current is present the diode is just like an open circuit. At a minimum an rf switch based on pin diodes needs a dc blocking capacitor to prevent the dc bias current from reaching the rf output and an rf choke to provide a path for the dc bias current to return while blocking the rf signal.