GaAs DSAs for high dynamic range


The DSA family is intended to ease the design of high dynamic range receivers and instrumentation. These applications often must accomplish gain control of 50dB or more.

Fine step DSAs (e.g., 0.5dB Least Significant Bit [LSB]) are often used for these applications. However, when a large attenuation change is needed, it is more efficient to use a lower bit count coarse (e.g., 2, 4 or even 8 dB LSB) step DSA MMIC as these parts offer lower insertion loss and fewer control lines for easier design implementation.

Table 1 summarizes the eight new products that are now available covering up to 40GHz, with 0.5, 2 and 4dB step size options. Die and QFN packaged versions are available.

The CMD281, CMD282, CMD281C3 and CMD282C3represent initial offerings for coarse control 2 bit DSAs with 2 and 4 dB step control. The CMD279, CMD280, CMD279C3 and CMD280C3 are the more traditional 0.5dB step control devices with 15.5dB range (5 bit). All devices are single control line per bit.

TABLE 1

 

Digital Step Attenuator   Part Number Frequency
(GHz)
Number of
Bits
Insert.
Loss
(dB)
Attn.
Range
(dB)
Step Size (dB) Input
IP3
(dBm)
Control
Voltage
(V)
Package
CMD282
DC – 40 2 1.5 12 4 42 0 / -5 DIE
CMD281
DC – 40 2 1.2 6 2 42 0 / -5 DIE
CMD280
DC – 30 5 3 15.5 0.5 42 0 / -5 DIE
CMD281C3 DC – 22 2 1.5 6 2 42 0 / -5 3×3 mm QFN
CMD282C3
DC – 22 2 1.9 12 4 42 0 / -5 3×3 mm QFN
CMD280C3 DC – 18 5 3 15.5 0.5 42 0 / -5 3×3 mm QFN
CMD279C3
2 – 18 5 3.5 15.5 0.5 42 0 / +5 3×3 mm QFN
CMD279
2 – 30 5 3.5 15.5 0.5 42 0 / +5 DIE

 



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