DATA SHEET • SMSA7621-060: SCHOTTKY DIODE

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May 7, 2015 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 203198B

Mixer and Detector Applications

24 GHz Detector Design

A detector circuit that incorporates an SMSA7621-060 Schottky

diode and covers the 24 GHz band is shown in Figure 2. The RF

arrives on a 50

Ω microstrip line from the left and is shorted to

GND by a 90 degree line with a stub (GND arrives by a via).

The cathode of the diode is directly connected to a 24 GHz stub.

This output is loaded by a 100 k

Ω resistor and a 100 pF

capacitor. The output voltage is fed to a 2-pin, 2.54 mm header.

The circuit was built on a 0.254 mm Rogers RO-4350B

substrate and measured with a power-variable 24 GHz source.

A layout design is illustrated in Figure 3.

Input power versus detected voltage for this detector is shown

in Figure 8.

λ/4

λ/4

Detected Voltage

100 k

Ω

100 pF

SMS7621-060

RF Input

Figure 2. Schematic of a 24 GHz Detector Design

Figure 3. Layout for a 24 GHz Detector Design

24 GHz Rat-Race Mixer

A rat-race mixer that uses two SMSA7621-060 Schottky diodes

is shown in Figure 4. The LO signal (24 GHz) is fed from the

right side and reaches a rat-race ring. The diodes are positioned

90 degrees apart from the LO input and are terminated in a

stub.

Both diodes are connected (using a 1206 resistor) and are

loaded by a 470

Ω resistor and a 10 pF capacitor. This forms

the IF output (10 MHz). The RF input (24.010 GHz) is directly

connected to the rat-race ring. A layout design is illustrated in

Figure 5.

The mixer has been tested with the following conditions:

LO frequency: 24 GHz

LO power:

0 to +5 dBm

RF frequency: 24.010 GHz

RF power:

–30 dBm

The IF output was loaded with 50

Ω. Measured conversion loss

data for this mixer is shown in Figure 9.

λ/4

100 k

Ω

100 pF

SMS7621-060

SMS7621-060

λ/4

λ/4

λ/4

3

λ/4

RF Input

LO Input

IF Out

Figure 4. Schematic of a 24 GHz Rat-Race Mixer

Figure 5. Layout for a 24 GHz Rat-Race Mixer