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App Note [1] Biasing - As shown in the bonding diagram, this device

operates using a self-biased architecture and only requires one drain bias.

Bias is nominally Vd=5V, I=115mA. Additionally there are three source

resistors on chip, 13, 12 and 8.5 Ohms. One of these must be bonded to

ground. Typically 12 Ohms is bonded to ground to achieve performance as

shown. Bonding to one of the other resistors or any or all in parallel may

allow additional performance adjustment.

App Note [2] Bias Arrangement - Each DC pad (Vd) needs to have DC

bypass capacitance (~100-200 pF) as close to the device as possible.

Additional DC bypass capacitance (~0.01 uF) is also recommended.

Current Select - At times the need to balance performance against system

power budgets forces a trade off between bias current, gain, P1dB, or other

parameters. This note includes information on how to use the built-in binary

bias ladder to adjust the currents enabling this trade off. The bias is controlled

by the self bias resistor network in the bottom right corner of the die. These

resistors have binary relative values so that you can step the current from a

minimum to a maximum with multiple different bias options available along

the way. The infinity option is not useful as there is no current flow with all

resistors open. Using the information from the current select table shown

here allows the user to set the resistors adjusting the current up or down

from a nominal value. In addition, the table can be used to estimate how to

make a change with minimum trial and error. The net result is that the current

can be adjusted over a wide range with incremental control.

Bonding Substrate - If you are concerned about dialing in the exact current

or making fine adjustments to the bias point it is recommended that a

bonding substrate, like the one shown here, be used. The purpose is to allow

the chip to substrate wire bonds to be left intact and not to be used for

adjustments. The bond wires that go from the substrate to ground are then

added or subtracted to tune the bias as necessary.

CMM4000-BD

2.0-18.0 GHz GaAs MMIC

Buffer Amplifier

Mimix Broadband, Inc., 10795 Rockley Rd., Houston, Texas 77099

Tel: 281.988.4600 Fax: 281.988.4615 mimixbroadband.com

Characteristic Data and Specifications are subject to change without notice.

©2009 Mimix Broadband, Inc.

Export of this item may require appropriate export licensing from the U.S. Government. In purchasing these parts, U.S. Domestic customers accept

their obligation to be compliant with U.S. Export Laws.

September 2009 - Rev 21-Sep-09

Left

Center

Corner

Delta Current

13

12

8.5

mA

0

0

0

Infinity

NA

1

0

0

13.00

-140

0

1

0

12.00

-130

110

6.24

-80

001

8.50

-55

101

5.14

-30

011

4.98

-25

111

3.60

Max

Net R

CMM4000 - Source Resistance Table