Silicon Motion FC5150 - Manual (Page 5)

FC5150
RF Silicon IC tuner
For Digital Cable TV standards
G
G
Preliminary 5 / 30 April. 2013
Future
Communications
Integrated circuit Inc.
AGC description
FC5150 signal path is composed of LNA, ATTEN2, TF+MIX, CSF, PGA and VGA. AGC adjusts the
gain of the rest of the block, except for the VGA. Using the each PD (peak detector) at each stage,
each block operates independently. The AGC budget is already considering linearity and noise floor.
Changes in units of ATTEN and PGA are 0.25dB, so the linear change is possible. The Final tuner
gain is externally controlled via IFAGC voltage level which is applied to pin AGC_BB.
Clock generation
XO_M/XO_OUT and XO_P pins generate a stable sine waveform which can provide demodulator
through XO_M/XO_OUT pin. The load on these outputs must be identical to ensure optimum
performance