low noise amplifiers

181 Pages·2010·9.82 MB·English

Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
t
Barrie Gilber
ADI Northwest
Portland, Oregon
ANALOG
DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
LOGARITHMIC AMPLIFIERS
ANALOG
DEVICES
• Unique Nonlinear Function AD606 AD8313
AD607 AD8314
• Integrated Multistage Systems
AD608 AD8315
• Calibrated Slope and Intercept
AD640 AD8316
• Provide Complete Solutions
AD641 AD8317
-- easy to use
AD8302 AD8318
• Up to 100 dB Dynamic Range
AD8306 AD8319
• Now covering DC - 30 GHz
AD8307 AD8362
• Limiter Versions for PSK, FSK
AD8309 AD8363
• Low Cost, Small Packages
AD8310 AD8364
• Numerous types available
AD8311 more…..
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
A Personal Goal: Make Log Amps as
Cheap, and Easy to Use, as Op Amps
ANALOG
DEVICES
2.7-7.5V
4.7Ω
10nF
N.C.
SIGNAL INPUT
-73dBm to +17dBm INP VPS ENB INT
(-86dBV to +4dBV)
AD8307
to +/-1dB error pts.
(100dB to +/-3dB)
INM COM OFS OUT
N.C. LOG OUTPUT
0.3 to 2.3V
20mV/dB
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
SO HERE’S THE PLAN….
 BEGIN WITH A BRIEF OVERVIEW OF THE
VARIOUS TYPES, TO SET THE STAGE
 MOVE ON AS QUICKLY AS POSSIBLE TO
PROGRESSIVE COMPRESSING TYPES
as likely to be of most value in beam instr.
 DEVELOP THEIR FUNDAMENTAL THEORY
starting from the most basic of foundations
 SHOW SOME PRACTICAL EMBODIMENTS
ANALOG
4 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
WHAT DO LOG AMPS DO?
 Convert signals of high dynamic range (HDR)
to a substantially smaller dynamic range
 The output is readily scaled to represent the decibel
value of the input, in simple units
 This is a fundamental nonlinear conversion of the
signal representation - with important consequences
 Some types may be used to simply compress a
HDR signal, thereby achieving high observational
or measurement-sensitivity near a nominal null
ANALOG
5 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
FUNDAMENTAL FUNCTION
X
____
W = Y log
Z
where
W is the Output variable
X . . . . . Input variable
Y . . . . . Slope parameter
Z . . . . . Log Intercept
ANALOG
6 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
FUNDAMENTAL FUNCTION
V
___X_
V = V log
W Y
V
Z
where
V is the Output voltage
W
V . . . . . Input voltage
X
V . . . . . Slope voltage
Y
V . . . . . Intercept voltage
Z
ANALOG
7 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
FUNDAMENTAL FUNCTION
I
__X_
I = I log
W Y
I
Z
where
I is the Output current
W
I . . . . . Input current
X
I . . . . . Slope current
Y
I . . . . . Intercept current
Z
ANALOG
8 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
FUNDAMENTAL FUNCTION
I
__X_
V = V log
W Y
I
Z
where
V is the Output voltage
W
I . . . . . Input current
X
V . . . . . Slope voltage
Y
I . . . . . Intercept current
Z
ANALOG
9 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES
Editor's Note: PDF version of slides from Beam Instrumentation Workshop 2010, Santa Fe, NM
THE BASIC LOGARITHMIC RELATIONSHIP

V
W
V = 5V
W Y
V = 4V
W Y
V = 3V
W Y
V = 2V
W Y
V = V
W Y
log V 
X
V = 0
W
-
V = 10 2V V = V V = 102 V V = 104 V
X Z X Z X Z X Z
- 40dBc 0dBc + 40dBc + 80dBc
ANALOG
10 BIW-10, Santa Fe, May 2010 © Barrie Gilbert DEVICES