1.25Msps, 12-Bit ADC Conserves Power and
Signal Integrity on a Single 5V Supply – Design Note 146
Kevin R. Hoskins
INTRODUCTION Complete ADC with Reference and Wideband S/H
The LTC1415 includes a 10ppm/В°C 2.5V reference that
is suitable for use as a system reference. This internal
reference sets the LTC1415’s full-scale input range from
0V to 4.096V. The circuit in Figure 2 trims the full-scale
(gain) error without placing additional circuitry in the
signal path. The new LTC®1415 expands LTC’s family of high speed,
low power 12-bit ADCs. Operating on a single 5V supply,
it is optimized for applications such as ADSL, HDSL,
modems, direct down-conversion, CCD imaging,
DSP-based vibration analysis, waveform digitizers and
multiplexed systems. The LTC1415’s block diagram is
shown in Figure 1. The LTC1415’s fully differential S/H has a typical 20MHz
input bandwidth and very good CMRR of 60dB or better over a DC to 10MHz bandwidth. AC specifications
are measured with single-ended (–A IN grounded)
signal drive. Offsetting –AIN above ground eases the
drive requirements of rail-to-rail op amps that drive the
LTC1415’s input. Single 5V Supply, High Speed, Lowest Power
The new LTC1415 has lower power dissipation and better performance and features than other 12-bit ADCs
currently on the market. It samples at 1.25Msps and …