CMH192 Datasheet, PDF (9/11 Pages) TriQuint Semiconductor – GaAs MMIC

GaAs MMIC CMH192
CMH192 – Application Information
DC Biasing:
Supply Voltage
One regulated voltage source is needed for CMH192. On the evaluation board it
is labeled VDD.
Minimum LO Power for Proper Biasing
For proper biasing of the CMH192, a minimum LO input power is required. If the
part is turned ON without any LO drive applied all currents will be extremely high.
The minimum LO required is approximately –9 dBm. Operation with LO input
powers below the minimum value causes the current to increase in all amplifier
stages. For higher LO input power levels the current stays relatively constant over a
wide range of LO powers. Proper matching of the LO amplifier is also important to
achieve the lowest current consumption and to minimize the required LO input
power.
Adjustable Current Level
The CMH192 can operate in two different current/linearity modes: High Linearity
(with higher current) and Reduced Current (lower linearity). To operate with reduced
current the voltage on pin 13 (RCV) should be set LOW. Some additional current
reduction can be achieved by reducing the voltage at pin 14 by placing a resistor
between VDD and pin 14. The current pulled by pin 14 is approximately 1 mA.
Higher currents can be realized by using a higher VDD voltage.
Tuning LO and IF Amplifiers:
The CMH192 can be tuned to utilize either high or low side LO frequencies and
allows a wide range of IF frequencies. Depending on the chosen frequency plan the
off chip components for the LO and IF amplifiers will need to be optimized. An
application circuit with all component values is provided for low side LO injection with
IF frequency of 210 MHz (RF freq 1930 – 1960 MHz)
Two external components (L6 and L7) are required for tuning the LO. L6 is
critical for setting the minimum current and to achieve the constant DC current over
the operating band. L7 sets the LO input match.
Components L4, C9 and C11 form the input match for the IF amplifiers and will
vary depending on the chosen IF frequency. The inductor on pin 8 allows
adjustment to the gain of the IF amplifier.
Output matching components shown in the application circuit provide a
transformation for a 50 Ohm load impedance. The output impedance for the IFA
(looking into pin 9) at 210 MHz is approximately (350 - j*515) Ohms.
CMH192 – Datasheet (October 1^st, 2002)
pg. 9/11