[AMPS] bias regulator

[John T. M. Lyles]

Xicor has introduced a Bias regulator chip made especially for use 
with LDMOS RF transistors. It uses active feedback from a drain 
current sensing resistor, to adjust the gate bias to keep the part at 
optimal Q point for, say, class AB1 idling current. It has an 
interface port for digital control, to force it into various states 
such as active adjusting, PA shutdown, PA transmit without 
adjustment, etc. Internally the chip uses one of their digital 
controlled potentiometers to make the adjustment, and has an 
instrumentation amp front end, an error amp and an output buffer amp. 
Its the X9470. Heres the blurb from their website. There is a PDF 
file press release but no datasheet that I could find:

>Xicor and Motorola Collaborate
>                   On "Smart Biasing" Solutions for RF Power Amplifiers
>
>                   MILPITAS, California - January 16, 2002 - Xicor, 
>Inc. (Nasdaq/NMS: XICO)
>                   announced today that they have teamed up with 
>Motorola to provide radio
>                   frequency power amplifier (RFPA) reference 
>platforms for GSM, EDGE and
>                   W-CDMA cellular basestation applications. These 
>reference platforms will
>                   incorporate Xicor's unique "Smart Biasing" ICs for 
>RFPA applications.


All the ricka-racka on screen voltage regulators for tetrodes 
reminded me to point out that the IC folks have it easy to build it 
all into a small ASIC device, while we tube types gotta fool around 
with MOSFETS, Zeners, spark gaps, and so on, to stabilize our beloved 
bottles. It sure would be wonderful if hams with huge egos would grow 
up and keep their contributions to AMPS@CONTESTING.COM at a 
technical, not personal, level. Its amazing how quickly the 
discussions seem to elevate to attack mode. I'm sure certain 
individuals will send me a stab for suggesting that, but .... just 
grow up.

73
John
K5PRO

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