IN MY OPINION

Interconnect Advances Fuel Technology Growth
By Orwill Hawkins, Vice President of Marketing, LadyBug Technologies

With increased frequencies, higher data rates, and lower noise levels, the microwave industry serves as a leader in technological capability. Demand for quality interconnects has increased right along with other higher-performance areas in the industry.
Read More...

MILITARY MICROWAVE DIGEST


MMD March 2014
New Military Microwave Digest

ON THE MARKET


E-Band Active X5 Multiplier
Model SFA-743843516-12SF-N1 is an E-band X5 active multiplier with center frequency at 79 GHz with minimum +/-5 GHz operational bandwidth. It converts 14.8 to 16.8 GHz/+5 dBm input signal to deliver 74 to 84 GHz frequency band with more than +16 dBm power.
Sage Millimeter

Hand-Flex™ Coaxial Cable
Covering DC to 12.5 GHz, this 8” coaxial cable, 141-8SMNB+, has a bulkhead Female Type-N connector at one end and SMA-Male at the other. Features include low loss, excellent return loss, hand formable, and an 8mm bend radius for tight installations.
Mini-Circuits

Phase Trimmer Series
This new phase trimmer series is designed for RF applications where phase match between two cables is needed for proper system performance. Phase trimmers, offered from DC to 50 GHz, will give an accurate phase adjustment over a specified frequency range.
RLC Electronics

Planar Monolithics Industries
Model PTRAN-100M18G-SFB-3UVPX-MAH is a transceiver covering the frequency range of 100 MHz to 18 GHz. The transceiver fits into a 3U Open VPX form factor utilizing the high speed VITA 67 RF connector.
Planar Monolithics Industries

SMT High-Power Attenuators
Now available with full design support capabilities are three new SMT high-power attenuators from Anaren. These 30 to 50W devices are high-performance, high-power chip attenuators covering DC to 3.0 GHz and feature high return loss and small footprints.
Richardson RFPD

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February 2012

50 W High Power Silicon PIN Diode SPDT Switch
By Rick Puente, Skyworks Solutions, Inc.

Radio transceiver designers have searched for a low cost solution to replace expensive mechanical switches and relays to direct high power transmit signals to the antenna and prevent that signal from entering the sensitive front end of the local receiver, while also allowing a low-loss connection between the antenna and the receiver. New low cost, solid state, PIN diode based switches, configured as transmit-receive (T-R) switches, perform this function.

QFN 16L

A High Power Handling Solid State T-R Switch
The SKY12207-306LF SPDT switch utilizes a series, shunt diode pair and one series PIN diode to achieve high-power handling, 50 watts CW and 200 watts peak, low insertion loss of 0.4 dB typical and high isolation of >40 dB at 2 GHz. The switch can be used in many applications, but its primary application is as a transmit-receive failsafe switch in the frequency range of 0.9 to 4.0 GHz for WiMAX, TD-SCDMA or LTE base stations. The device is provided in a 4 x 4 x 0.9 mm, 16-pin Quad Flat No-Lead (QFN) package.

The internal circuitry of the SKY12207-306LF is shown in Figure 1. The circuit is a reflective, single pole double throw switch with asymmetrical sections. The RX side utilizes a low resistance single series diode and a shunt diode for low loss and high isolation. A small MIS chip capacitor connected to the shunt diode provides an AC-ground return. The TX side incorporates a single series diode capable of handling high RF power. These two ports are connected to a common antenna port labeled “ANT.”

Figure 1: The SKY12207-306LF Circuit

This switch is operated in one of two discrete states as shown in Figure 2. In ANT-RX mode, the series diode on the RX side of the switch is forward-biased, resulting in low impedance and low insertion loss between the antenna port and the RX port. At the same time, the series TX diode and the RX_BIAS shunt diode on the RX side of the switch is in the reverse-bias state, which provides high impedance resulting in high isolation between the TX port and the antenna port.

In ANT-TX mode, the series diode on the TX side and the RX_BIAS shunt diode on the RX side of the switch is forward-biased, resulting in low impedance and low insertion loss between the antenna port and the TX port. At the same time, the series RX diode is in the reverse-bias state, which provides high impedance resulting in high isolation between the RX port and the antenna port.

Figure 2: The SKY12207-306LF Switch States

Most new radio designs can only support positive value bias control. The SKY12207-306LF operates with either a 5V or 28V positive supply to provide the voltage differentials needed for reverse bias. Positive-forward currents are achieved by applying a positive voltage across external resistors R2 and R3. Figure 3 shows the external-bias circuitry, which includes RF chokes, RF bypass and DC blocking capacitors for use in most applications.

In the ANT-TX mode, the low insertion loss state is produced by applying 50 mA of forward bias to the TX series diode and RX side shunt diode while the RX series diode is reversed biased with 28 V. In the ANT-RX mode, the low insertion loss state is produced by applying 50 mA of forward bias to the RX series diode while the TX and the shunt diode on the RX side are reversed biased with 28V.

Figure 3: The SKY12207-306LF Schematic Circuit

When large signals are applied to a PIN diode, the RF electric field forces charge carriers into the I-layer, thereby reducing the diode’s impedance. In other words, the resistance decreases as input power increases. A substantial reverse bias is applied to the PIN diode to hold the diode in its high-impedance state in the presence of RF voltages large enough to instantaneously apply forward voltage to the diode and possibly into conduction. The magnitude of reverse voltage required in a high-power switch depends on frequency, RF voltage and PIN diode I-region width. For the SKY12207-306LF switch at 50 watts incident power, 28 volts reverse voltage is specified. This was determined experimentally and conforms to theoretical analysis. The larger reverse bias voltage also reduces harmonic and intermodulation distortion produced by the nonconducting PIN diode.

Figure 4: The SKY12207-306LF Performance Data

The SKY12207-306LF Performance
Table 1 indicates typical performance of the SKY12207-306LF. The data was taken at: TA = 25°C, Z0 = 50 Ohms.

Table 1: Typical Performance of the SKY12207-306LF

Conclusion
Radio transceiver designers now have a low cost solution to replace expensive mechanical switches and relays. Skyworks Solutions has introduced the SKY12207-306LF, a solid state, high power, T-R switch which can handle 50 W CW, 200 W peak transmitter power operating from 0.90 to 4.0 GHz.

Also available from Skyworks Solutions is the SKY12208-306LF 50W, high power T-R switch, operating from 0.02 to 2.70 GHz. Samples are also available of the new SKY12210-478LF 100 Watt High Power SPDT switch, operating from 0.90 to 4.0 GHz, that addresses the higher power requirements of TDD-LTE within infrastructure applications.

References
1. Design with PIN Diodes, Skyworks’ Application Note APN1002.
2. R. Caverly and G. Hiller, “Distortion in PIN Diode Control Circuits”, IEEE Trans. on Microwave Theory and Techniques, vol. MTT-35, p. 492, May 1987.
3. R. Caverly and G. Hiller, Establishing the Minimum Reverse Bias for a PIN Diode in a High Power Switch, IEEE Trans. on Microwave Theory and Techniques, vol. MTT-38, p. 1938, Dec. 1990.

For more information, please visit our website.

SKYWORKS INC.
www.skyworksinc.com
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Uncertain Times for DefenseIn Defense of DARPA; Lamenting Bell Labs
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A federal agency like DARPA is a sitting duck for politicians and assorted other critics. It has come up with some truly bizarre programs over years that ultimately either delivered no tangible results, were canceled before they could cause any damage, or attempted to answer questions that nobody was asking or needed answers to. Read More...


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