Black Sand CMOS PAs target 3G

Today, Black Sand Technologies announced an array of six power amplifiers (PAs) in two separate product families for 3G applications. One family, the BST34 is a drop-in replacement for GaAs PAs, in an effort to encourage transition in existing designs. The second is the BT35 series, which includes an integrated power detector. Last week, I spoke with Jim Nohrden at Black Sand in advance of today's announcement.

Black Sand tells me that the BST3401 and BST3501 chips and evaluation boards will begin sampling next month. To get a look at the rest, we will need to wait until the second quarter. For those of you following the development of CMOS PAs closely, Black Sand has the benefit of having on staff the Silicon Labs team that worked on 2G CMOS PAs, and it reports more than 70 patents and applications for CMOS PA design. Let's get to the nuts and bolts...

Key Features BST34 series:

• 3x3mm 10pin package
• Integrated directional coupler
• Daisy-chain compatible
• Compliant with 3GPP WCDMA, HSDPA, HSUPA
• +28dBm output power in high-power mode
• +19dBm output power in medium-power mode
• 40% efficiency

Key Features BST35 series:

• Integrated power detector
• 1dB improvement in total radiated power (TRP) as compared to GaAs PA with coupler and power detector
• Up to 3dB improvement in TRP as compared to GaAs PA with integrated coupler
• +28dBm output power in high-power mode
• +19dBm output power in medium-power mode
• 40% efficiency

Here is a performance representation of BlackSand's TrueDelivered power detector:


RF&MW Designline: Traditionally, it has been challenging to get CMOS PAs to handle higher frequencies, how did you approach that?
Black Sand: Our PAs cover the most common 3G high bands. We chose the higher frequencies first because we wanted to be sure that our architecture could do that. We will be sampling our first one in February.

RF&MW Designline: Also a challenge to achieve high power, high efficiency and high linearity simultaneously, how did you to that, and please don't say 'clever engineering'!
Black Sand: We are using 100% standard RF CMOS. We are not using process tricks, but using circuit design. All of our IP is at the circuit level. All of our PAs have high, medium, and low-power modes, and you rarely need the high-power one. Our medium-power mode, for instance, goes up to +19dBm, while most competitors go up to +17dBm.

Availability:
The BST34 product line includes: BST3401 for “2100” Band-1 (1920-1980 MHz), BST3402 for PCS Band-2 (1850-1910 MHz) and BST3404 for AWS Band-4 (1710-1755 MHz), Japanese Band-9 (1749.9 - 1784.9 MHz) and Latin American Band-10 (1710-1770 MHz).  
The BST35 product line includes: BST3501 for “2100” Band-1 (1920-1980 MHz), BST3502 for PCS Band-2 (1850-1910 MHz) and BST3504 for AWS Band-2 (1710-1755 MHz), Japanese Band-9 (1749.9 - 1784.9 MHz) and Latin American Band-10 (1710-1770 MHz).  These 3 products are packaged in a 3x3mm 10pin package.

The BST3401 and BST3501 chips and evaluation boards are sampling in February. The BST3402, BST3502, BST3404 and BST3504 will sample in Q2 2011.

More information:
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