For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824

Phone: 978-250-3343

Fax: 978-250-3373

Order On-line at www.hittite.com

Application Support: Phone: 978-250-3343 or apps@hittite.com

8

HMC980

v00.0312

Active BiAs controller

High current

pad number

Function

Description

interface schematic

15

alMh

a high precision resistor (e.g. 0.5%, ±25 ppm tCr) to

iset pad is recommended for good bias accuracy. the

value of the resistor sets the threshold. if alarm feature

is not used alMh can be shorted to iset.

16

iset

a high precision resistor (e.g. 0.5%, ±25 ppm tCr)

between alMl and iset is recommended for good bias

accuracy. the total external resistance from iset pad to

GnD should always be equal to 5 k Ω.

17

alMl

a high precision resistor (e.g. 0.5%, ±25 ppm tCr)

to GnD is recommended for good bias accuracy. the

value of the resistor sets the threshold value for under

current alarm. if alarm feature is not used alMl can be

shorted to iset.

18

isense

Drain current adjustment pad. to adjust the bias current

of the external amplifier connect a resistor (rsense)

from isense pad to GnD according to eqn(2) on page

13-15. a high precision resistor (e.g. 0.5%, ±25 ppm

tCr) is recommended for good bias accuracy.