HMC594_ データシートの表示（PDF） - Hittite Microwave
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HMC594_ Datasheet PDF : 18 Pages
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HMC981
ACTIVE BIAS CONTROLLER
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Figure 1. Daisy Chain Operation
Operation Modes
HMC981 can be configured to bias both enhancement and depletion mode external amplifiers. The mode of operation
can be selected by setting two pads (VNEGFB, VGATEFB) as tabulated in Table-2. The connection to the VNEGIN
should be adjusted accordingly.
In order not to bias external amplifier in a wrong region, please make sure that the correct mode of operation is
selected before powering up the HMC981.
The HMC981 does not allow the internal negative voltage generator to work if an enhancement mode is selected.
Therefore, if VNEGFB is left floating while VGATEFB is grounded, HMC981 will stay in standby mode.
Please note that the external negative voltage should be between -2.5V to -3.5V for HMC981 to operate. If your
application requires negative voltages outside this range please contact Hittite application support.
Table 2 - Mode Selection
VNEGFB
MODE1
(Depletion/Master Mode)
FLOAT
VGATEFB
FLOAT
MODE2
(Depletion/Slave Mode)
---
MODE3
(Enhancement Mode)
GND
FLOAT
GND
FLOAT
GND
GND
VNEGIN
Connected to
VNEGOUT
Connected to
External VSS
N/A
Connected to
GND
Description
Depletion mode transistor. Internal negative voltage generator is
active and generates -2.5V. Sample application schematic given
shown in Fig.2a.
Depletion mode transistor. Internal negative voltage generator is
disabled. An external negative voltage less than -2.3V should be
connected to VNEGIN. Sample application schematic given shown
in Fig.2b.
Not allowed. HMC981 stays in standby.
Enhancement mode transistor. Internal negative voltage generator is
disabled. Sample application schematic given shown in Fig.2c.
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
2 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
Order On-line at www.hittite.com
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