Silicon Schottky Diode Chips Features ■ For Detector and Mixer Applications ■ Low Capacitance for Usage Beyond 40 GHz ■ ZBD and Low Barrier Designs ■ P-Type and N-Type Junctions ■ Large Bond Pad Chip Design Description In a detector circuit operating at zero bias, depending on the video load impedance, a ZBD device with RV less than 10 kΩ may be more sensitive than a low barrier diode with RV greater than 100 kΩ. Applying forward bias reduces the diode video resistance as shown in Figure 2. Lower video resistance also increases the video bandwidth but does not increase voltage sensitivity, as shown in Figure 3. Biased Schottky diodes have better temperature stability and also may be used in temperature compensated detector circuits. Alpha’s product line of silicon Schottky diode chips are intended for use as detector and mixer devices in hybrid integrated circuits at frequencies from below 100 MHz to higher than 40 GHz. Alpha’s “Universal Chip” design features a 4 mil diameter bond pad that is offset from the semiconductor junction preventing damage to the active junction as a result of wire bonding. As power-sensing detectors, these Schottky diode chips all have the same voltage sensitivity so long as the output video impedance is much higher than the video resistance of the diode. Figure 1 shows the expected detected voltage sensitivity as a function of RF source impedance in an untuned circuit. Note that sensitivity is substantially increased by transforming the source impedance from 50 Ω to higher values. Maximum sensitivity occurs when the source impedance equals the video resistance. P-type Schottky diodes generate lower 1/F noise and are preferred for Doppler mixers and biased detector applications. The bond pad for the P-type Schottky diode is the cathode. N-type Schottky diodes have lower parasitic resistance, RS, and will perform with lower conversion loss in mixer circuits. The bond pad for the N-type Schottky diode is the anode. Electrical Specifications at 25°C CJ1 (pF) RT2 Ω) (Ω VF @ 1 mA (mV) VB3 (V) RV @ Zero Bias Ω) (kΩ Max. Max. Min.–Max. Min. Typ. 0.25 30 135–240 1 5.5 Part Number Barrier Junction Type CDC7630-000 ZBD P CDC7631-000 ZBD P 0.15 80 150–300 2 7.2 526-006 CDB7619-000 Low P 0.10 40 275–375 2 735 526-006 CDB7620-000 Low P 0.15 30 250–350 2 537 526-006 CDF7621-000 Low N 0.10 20 270–350 2 680 526-011 CDF7623-000 Low N 0.30 10 240–300 2 245 526-011 Outline Drawing 526-006 1. CJ for low barrier diodes specified at 0 V. CJ for ZBDs specified at 0.15 V reverse bias. 2. RT is the slope resistance at 10 mA. RS Max. may be calculated from: RS = RT - 2.6 x N. 3. VB for low barrier diodes is specified at 10 µA. VB for ZBDs is specified at 100 µA. Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email [email protected] • www.alphaind.com Specifications subject to change without notice. 8/01A 1 Silicon Schottky Diode Chips Typical Performance Data Detected Voltage (mV) 10000 DETECTOR VOLTAGE RF SOURCE IMPEDANCE 1000 PInput RFC VIDEO LOAD IMPEDANCE 500 Ω 100 200 Ω 100 Ω Zero Biased Detector 50 Ω 10 25 Ω DETECTOR VOLTAGE 1 RF SOURCE IMPEDANCE 0.1 -40 -30 -20 -10 0 RFC PInput VIDEO LOAD IMPEDANCE 10 Input Power (dBm) Biased Detector Figure 1. Detected Voltage vs. Input Power and RF Source Impedance 10000 Detected Voltage (mV) Video Resistance (Ω) 100000 Low Barrier 10000 ZBD 1000 100 1 10 +10 dBm 1000 100 10 1 -30 dBm -20 dBm 0.1 -10dBm 0.01 0.001 0.001 100 0 dBm 0.01 0.1 1 10 Forward Current (mA) Forward Bias (µA) Figure 2. Video Resistance vs. Forward Bias Current Figure 3. Detected Voltage vs. Forward Current SPICE Model Parameters 2 Parameter CDB7619 CDB7620 CDF7621 CDF7623 CDC7630 CDC7631 Units IS 3.70E-08 5.40E-08 4.0E-08 1.1E-07 5.0E-06 3.8E-06 A Ω RS 9 14 12 6 20 51 N 1.05 1.12 1.05 1.04 1.05 1.05 TT 1E-11 1E-11 1E-11 1E-11 1E-11 1E-11 S CJ0 0.08 0.15 0.10 0.22 0.14 0.08 pF M 0.35 0.35 0.35 0.32 0.40 0.4 EG 0.69 0.69 0.69 0.69 0.69 0.69 XTI 2.0 2.0 2.0 2.0 2.0 2.0 FC 0.5 0.5 0.5 0.5 0.5 0.5 eV BV 2.0 4.0 3.0 2.0 2.0 2.0 IBV 1.00E-05 1.00E-05 1.0E-05 1.0E-05 1.0E-04 1.0E-04 A VJ 0.495 0.495 0.495 0.495 0.340 0.340 V Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email [email protected] • www.alphaind.com Specifications subject to change without notice. 8/01A V Silicon Schottky Diode Chips Outline Drawing Absolute Maximum Ratings 526-006, 526-011 Characteristic 0.015 (0.38 mm) 0.013 (0.33 mm) 0.015 (0.38 mm) 0.013 (0.33 mm) Reverse Voltage (VR) BONDING PAD DIAMETER 0.0035 (0.089 mm)– 0.0045 (0.114 mm) Value Voltage Rating Forward Current (IF) 50 mA Power Dissipation (PD) 75 mW Storage Temperature (TST) -65°C to +150°C Operating Temperature (TOP) -65°C to +150°C 0.0085 (0.216 mm) 0.0065 (0.165 mm) 526-006 = Cathode bond pad. 526-011 = Anode bond pad. Alpha Industries, Inc. [781] 935-5150 • Fax [617] 824-4579 • Email [email protected] • www.alphaind.com Specifications subject to change without notice. 8/01A 3