HSMP-382x: below 500 MHz switch HSMP-389x: 0.5 - 2 GHz switch HSMP-4890: above 2 GHz shunt switch HSMP-386x: low cost switch HSMP-3880: specialty high power switch

Alternatives:

Features:

Key Parameters:

Insertion Loss:

tenths of dBs

for series configuration, need low R

for shunt configuration, need low C

Isolation:

20+ dB for single diode, 30+ for diode pair

for series configuration, need low C

for shunt configuration, need low R

Switching speed (reverse recovery time):

HSMP-389x: 100 nsec

HSMP-382x: 7 nsec

HSMP-386x: unspecified

HSMP-388x: 550 nsec

Power handling capability:

HSMP-389x: 0.5 Watt

HSMP-382x: 1 Watt

HSMP-386x: 0.5 Watt

HSMP-388x: >5 Watts

f _DR (Dielectric relaxation frequency):

HSMP-389x: >3 GHz

HSMP-382x: >3 GHz

HSMP-386x: 500 MHz

HSMP-388x: 100 MHz

Markets:

Switch Diode Terms

Dielectric relaxation frequency (f _DR)

What:

the frequency above which the capacitance of a PIN diode becomes independent of bias voltage.
f_DR = 1 / (2 )

      where is the I layer bulk resistivity

      and = 1 E -12 F/cm

for a typical epi diode, =10 and f _DR = 16 GHz [switch diode]

for a typical bulk diode, =2000 and f _DR = 80 MHz [attenuator or switch diode]

Goodness:

A lower dielectric relaxation frequency means a wider range over which the diode will achieve minimum capacitance without external bias. In general, a low dielectric relaxation frequency is a desirable property for a diode intended to be used as a switch in a battery operated application.

Insertion Loss (I.L.)

What:

the loss of signal attributed to the diode when a switch is on (transmission state).

for a series diode switch, insertion loss can be calculated from:
I.L. = 20 log (1 + R/100)

(low resistance is needed)

for a shunt diode switch, insertion loss can be calculated from:
I.L. = 10 log [ 1 + (50 f C)²]

(low capacitance is needed, particularly at high frequencies)

Goodness:

less is better.

Isolation

What:

the measure of RF leakage between input and output when a switch is off.
for a series diode switch, insertion loss can be calculated from: I.L. = 10 log [1 + 1/(200 f C)²]

(low resistance is needed for high isolation)

for a shunt diode switch, insertion loss can be calculated from:
I.L. = 20 log ( 1 + 25/R)

(low capacitance is needed for high isolation, particularly at high frequencies)

Goodness:

higher is better.

Power Handling Capability

What:

The RF power (Continuous Wave or pulsed) that can be handled safely by a diode switch. This number is limited by two factors: breakdown voltage and thermal resistance. Other factors that may influence power handling capability include ambient temperature, frequency, attenuation level, and pulse characteristics.

Goodness:

high power handling capability is better.

Switching Speed (also called Reverse Recovery Time)

What:

Reverse recovery time measures the time to switch the diode from ON to OFF. It depends on both the forward and reverse bias applied. With forward bias current, charge is stored in the I layer of the PIN diode. When a reverse pulse is applied, reverse current will flow for a brief period of time, known as the delay time, t_d. When a sufficient number of carriers have been removed, current begins to decrease. The time required for the reverse current to decrease form 90% to 10% is called the transition time, TT. The sum, t_d + TT, is the reverse recovery time.

Goodness:

low reverse recovery time is better.