RF digital step attenuators offer ultra-high linearity

March 09, 2016 // By Graham Prophet
A family of RF devices from IDT targets broadband and CATV markets; the F1975 and F1977 75-Ohm digital step attenuators deliver linearity and glitch-free operation to support increased data rates

“DSAs (digital step attenuators) provide gain control in a wide range of applications including CMTS, fibre distribution networks, HFC distribution nodes, and CATV infrastructure and data network equipment,” said Chris Stephens, general manager of IDT’s RF division. “[these] DSAs address the increased data rates required for data-intensive applications including the latest DOCSIS 3.1 requirements.”

 

The F1975 and F1977 deliver very low insertion loss and distortion, and have much higher power handling with attenuation accuracy than competing devices. IDT’s “Glitch-Free” capabilities help to ensure low overshoot and ringing during MSB transitions. F1977 is the first monolithic silicon, 75-ohm Glitch-Free, 7-bit DSA, enabling designers to achieve 0.25 dB gain control while maintaining RF performance.

 

 





Parameter

F1975 (4x4mm)

F1977 (5x5mm)

Units

Frequency range

5-3000

5-3000

MHz

# Bits / Step Size

6 / 0.5dB

7 / 0.25dB

 

Max Operating Power

up to 28

 up to 28

dBm

P0.1dB (1 GHz)

 31

 32

dBm

Insertion Loss (1GHz)

1.2

1.4

dB

Return Loss

18

18

dB

Max Step Error (1 GHz)

0.1

0.1

dB

IIP3 (1 GHz)

64

64

dBm

 

F1975 is priced at $1.16 in a 4 x 4 mm 20-TQFN package; F1977is $1.45 in a 5 x 5 mm 32-QFN package (both 10,000).

 

IDT RF; www.idt.com