RF9957 Datasheet, PDF(4/10 Page) RF Micro Devices – CDMA/FM RECEIVE AGC AND DEMODULATOR

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RF9957 Datasheet, PDF (4/10 Pages) RF Micro Devices – CDMA/FM RECEIVE AGC AND DEMODULATOR

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RF9957

Pin Function Description

Interface Schematic

IN SEL

Selects between CDMA and FM mode. This is a digitally controlled

BIAS

input. A logic âhighâ (â¥VCC-0.7VDC) selects CDMA mode. A logic âlowâ

(<0.5VDC) selects FM mode. In FM mode, ONLY the I mixer is active.

60 kâ¦

There is no Q output in FM mode. The impedance on this pin is 30kâ¦.

IN SEL

60 kâ¦

Q OUT- Balanced Baseband Output of Q Mixer. This pin is internally DC biased

and should be DC blocked externally. This output is active in CDMA

mode, but is NOT active in FM mode. The output can be used in a sin-

gle-ended configuration by leaving one of the two pins unconnected,

however half the output voltage will be lost. Each pin should be loaded

with 2.5kâ¦. The balanced load should be 5kâ¦. The single-ended output

impedance is 1kâ¦, while the balanced output impedance is 2kâ¦.

VCC

1 kâ¦

Q OUT+

Q OUT-

Q OUT+ Same as pin 15, except complementary output.

See pin 15.

GND

Same as pin 6.

FL-

Balanced AGC Output/Demod Input. This balanced node is pinned out

to allow shunt filtering of the AGC output signal as it enters the demod-

ulator. The basic configuration of the filter should consist of a shunt

inductor and shunt capacitor, both connected to the power supply, as

the internal circuitry requires this power supply connection through the

inductor to operate.

FL- FL+

VCC2

1.2 kâ¦ 1.2 kâ¦

VCC1

FL+

Same as pin 18, except complementary.

See pin 18.

GND

Same as pin 6.

I OUT+

Balanced Baseband Output of I Mixer. This pin is internally DC biased

and should be DC blocked externally. This output is active in both

CDMA and FM modes. The output can be used in a single-ended con-

figuration by leaving one of the two pins unconnected, however half the

output voltage will be lost. Each pin should be loaded with 2.5kâ¦. The

balanced load should be 5kâ¦. The single-ended output impedance is

1kâ¦, while the balanced output impedance is 2kâ¦.

VCC

1 kâ¦

I OUT+

I OUT-

Same as pin 21, except complementary output.

See pin 22.

Analog Gain Control for AGC Amplifiers. The valid control range is from

BIAS

0.5 to 2.5VDC. These voltages are valid for ONLY a 37kâ¦ source

impedance. The gain range for the AGC is 95dB.

21 kâ¦

40 kâ¦

7-30

Rev C11 010622

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