CMH192 Datasheet, PDF (10/11 Pages) TriQuint Semiconductor – GaAs MMIC

GaAs MMIC CMH192
Downconverter Gain Adjustment:
The Downconverter gain can be adjusted by changing the source feedback
inductor L3 for the IFA. Higher inductance will give lower downconverter gain and
typically improve the IIP3.
Gain/Current Control Pins:
LOW = 0 to 0.2 V
HIGH = Vdd to (Vdd – 0.2) V
VGAIN – select between high and low gain states in the LNA.
VGAIN = HIGH: LNA ON (~12 dB Gain, ~ 6.5 mA current)
VGAIN = LOW: LNA bypassed (~ 4 dB Loss, no current)
VRCV - selects Current/Linearity mode (changes current in LNA/RFA/IFA)
VRCV = LOW selects Reduced Current Mode
VRCV = HIGH selects High Linearity Mode.
Other Notes:
Inductor L1 is critical for setting the Noise Figure of the LNA. A high Q wire wound
inductor (e.g. Coilcraft) is recommended to achieve minimum NF.
Inductor L5 and Capacitor C10 form a “tank circuit” to terminate the RF in the mixer.
These components should be placed in parallel close to pin 4. These elements may
require tuning depending on component vendor and board parasitics to achieve flat
conversion gain vs. frequency.
Inductor L8 is necessary for proper operation of the circuit for ESD protection.
Lower RF frequencies (i.e. Korean PCS or GPS) may be accommodated by adding
inductance between the LNA and RFA VDD pins and their bypass capacitors.
LNA current can be determined by subtracting the current in Low Gain mode from
the current in High Gain mode (keeping VRCV and VMODE constant).
Control lines (G_CNTL, VRCV and VMODE) have an input impedance of greater
than 1 MΩ when Vdd is ON. When VDD is off, they have approximately 20 KΩ input
impedance.
CMH192 – Datasheet (October 1^st, 2002)
pg. 10/11