A new 80 Msps, 14-bit analog to digital converter (ADC) from Linear Technology can provides designers of cellular base stations with a dramatic improvement in dynamic performance, according to the company. The LTC1750 eliminates the second intermediate frequency (IF) down-conversion stage. The device provides wide input bandwidth and dynamic performance for direct IF digitizing applications. The ADC undersamples up to 500 MHz input frequencies and delivers 84 dB spurious-free dynamic range (SFDR) with 140 MHz inputs and 74 dB SFDR with 350 MHz inputs. The device's wide bandwidth and AC performance are ideal for use in cellular base stations and broadband software radios, where it can directly digitize the first IF and eliminate the second IF down-conversion stage.
This ADC offers the flexibility to configure the input and the output specifically for the application. An on-chip programmable gain amplifier (PGA) allows multiple input ranges to optimize the performance. The larger input range offers low noise, and the smaller range lowers the gain requirements on the drive circuitry, making it easier to meet the IP3 requirements. If the input ever goes out of range, there is automatic indicator on the overflow pin. A separate digital output supply pin allows connection to low voltage DSPs, FIFOs or logic as low as 0.5 V.
Pricing for 1000-piece quantities begins at $32.30 each for the LTC1750.