Power-Supply Sequencing

The MAX2102/MAX2105 have several +5V supply pins.

The supply layout should be in a star format, with a

bypass capacitor that dominates the rise time of the

supply at the center of the star, to ensure that all pins

see approximately the same voltage during power-up.

is not used. Leaving PSGND open will disable the

prescaler function and, in this state, the prescaler will

not dissipate any power.

Systems Consideration: Lowpass Filters in

Direct-Conversion Tuners

Typically, a 5th or 7th-order L-C lowpass filter is used

for anti-aliasing the ADCs following the MAX2102.

Figures 4 and 5 describe typical filtering requirements.

Table 1 offers suggested component values for these

lowpass filters.

Chip Information

TRANSISTOR COUNT: 1852

SUBSTRATE CONNECTED TO GND

Direct-Conversion Tuner ICs for

Digital DBS Applications

14

______________________________________________________________________________________

Q

I

“1”

“2”

“3”

“4”

MATCHED FILTERS

DIGITAL SIGNAL PROCESSING

ANALOG LP FILTERS

ADCs

MAX2102

MAX2105

Figure 4. I, Q Signal Path