Description
The F1978 Digital Step Attenuator (DSA) is a product in IDT’s
Glitch-FreeTM DSA Family, which is optimized for the demanding
requirements of CATV and satellite systems. It operates in the
frequency range of 5MHz to 3000MHz. This device is offered in a
compact 4mm  4mm, 20-pin Thin QFN package with a 75Ω
impedance for ease of integration.
The F1978 DSA has RF performance identical to the F1975
Digital Step Attenuator. The difference between the F1978 and
F1975 is that the F1978 has an additional programming mode
called Direct Serial Programming. Consult the “Programming”
section of this datasheet or the application note AN-945
“Comparison of F1975 and F1978 Digital Step Attenuator
Serial Programming Methods.”

Features
 Frequency: 5MHz to 3000MHz
 Serial and 6-bit parallel interface
 31.5dB control range
 0.5dB step
 Glitch-FreeTM technology, low transient overshoot
 3.0V to 5.25V supply
 1.8V or 3.3V control logic
 Attenuator step error: 0.1dB at 1GHz
 Low insertion loss: 1.2dB at 1GHz
 Ultra-linear IIP3: +64dBm
 IIP2: +125dBm typical
 Stable integral non-linearity over temperature
 Low current consumption: 550µA typical
 Bi-directional
 Operating temperature: -40°C to +105°C
 4mm  4mm, 20-TQFN package