3

Quad Capacitance

Capacitance of Schottky diode quads is measured using

an HP4271 LCR meter. This instrument effectively isolates

individual diode branches from the others, allowing ac‑

curate capacitance measurement of each branch or each

diode. The conditions are: 20 mV R.M.S. voltage at 1 MHz.

Avago defines this measurement as “CM”, and it is equiv‑

alent to the capacitance of the diode by itself. The equiv‑

alent diagonal and adjacent capaci‑tances can then be

calculated by the formulas given below.

In a quad, the diagonal capacitance is the capacitance be‑

tween points A and B as shown in the figure below. The

diagonal capacitance is calculated using the following

formula

SPICE Parameters

Parameter

Units

HSMS-282x

B

V

V

15

C

J0

pF

0.7

E

G

eV

0.69

I

BV

A

1E‑4

I

S

A

2.2E‑8

N

1.08

R

S

Ω

6.0

P

B

V

0.65

P

T

2

M

0.5

ESD WARNING: Handling Precautions Should Be Taken To Avoid Static Discharge.

Linear Equivalent Circuit Model Diode Chip

The equivalent adjacent capacitance is the capacitance

between points A and C in the figure below. This capaci‑

tance is calculated using the following formula

A

B

C

1

1

1

1

–– + –– + ––

This information does not apply to cross‑over quad di‑

odes.

1

1

1

1

–– + –– + ––

where

T = temperature, K

n = ideality factor (see table of SPICE parameters)

Note:

To e ectively model the packaged HSMS-282x product,

please refer to Application Note AN1124.