CMH82
Downconverter Gain Adjustment:
The Downconverter gain can be adjusted by changing the source feedback
inductor L6 for the IFA. Higher inductance will give lower downconverter gain and
typically improve the IIP3.
Gain/Current Control Pins:
LOW = 0 to 0.3 V
HIGH = Vdd to (Vdd – 0.3) V
VGAIN – select between high and low gain states in the LNA.
VGAIN = HIGH : LNA ON (~12 dB Gain, ~ 6 mA current)
VGAIN = LOW : LNA bypassed (~ 4 dB Loss, no current)
VRCV - selects Current/Linearity mode (changes current in LNA/RFA/IFA)
VRCV = LOW
VRCV = HIGH
selects Reduced Current Mode
selects High Linearity Mode.
VMODE - selects which IF amplifier is ON
VMODE = LOW selects AMPS mode
VMODE = HIGH selects CDMA 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.
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).
Capacitor C14 can be eliminated if a slightly higher (~0.5 dB) downconverter noise
figure is tolerable.
Control lines (G_CNTL, VRCV and VMODE) have an input impedance of > 1 MW
when Vdd is ON. When VDD is off, they have approximately 20 KW input impedance.
CMH82 - Preliminary Datasheet (Rev 3nl, 1/02)
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TRIQUINT [ TRIQUINT SEMICONDUCTOR ]
