Description

The LT5554 is a 7-bit digitally controlled programmable gain (PG) amplifier with 16dB gain control range. It consists of a 50? input variable attenuator, followed by a high linearity variable transconductance amplifier. The coarse 4dB input attenuator step is implemented via 2-bits of digital control (PG5, PG6). The ?ne transconductance amplifier 0.125dB step within 3.875dB gain control range is set via 5-bits digital control (PG0 to PG4). The LT5554 gain control inputs (PGx) and the STROBE input can be directly coupled to TTL or ECL drivers. The seven parallel gain control inputs time skew can be eliminated by using the STROBE input positive transition.The internal output resistor RO = 400? limits the maximum overall gain to 36dB for open outputs. The internal circuitry of open output collectors enables the LT5554 to be unconditionally stable over any loading conditions (including external SAW ?lters) and provides ?80dB reverse isolation at 300MHz.The LT5554 is internally protected during overdrive and has an on-chip power supply regulator.With 0.125dB step resolution and 5ns settling time, the LT5554 is suitable in applications where continuous gain control is required.Applications Differential ADC Driver IF Sampling Receivers VGA IF Power Ampli?er 50? Driver Instrumentation

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Part number: DC1150A

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