24 October 2011

App Note 47 part 6

The last piece of App Note 47 that I want to discuss is the references. This app note has 46 interesting and useful references. (You know you're a hopeless academic when you spend time studying other people's references.) The list of references can actually be broken down into a dozen broad categories:

  • The excellent Tektronix Concept Series books [1,8,42]
  • Linear Technology App Notes [2,9-11,14,19,35,40]
  • Chapters from Jim's first book [3,12,13,46]
  • Some general history references [4-6,41]
  • Tektronix service manuals (always good for inspiration!) [7,25,29]
  • Articles about settling time [15-17] and scope measurement [34]
  • A private communication with John Addis [18]
  • Articles about bridge oscillators [20-24,30]
  • Analog multipliers [26,27], op amps [31,32,38], and converters [33]
  • Hewlett Packard Schottky diodes [28] and photodiodes [37]
  • Shielding and noise reduction techniques [36,39]
  • Some subtleties of transistor circuits [43,44,45]

I found it interesting and entertaining to actually go through the main text and look at the places that cited the references. (Curiously, ten of the references are not cited in the text of the app note... I just can't find references [30-39] mentioned anywhere.) Here are the quotes and excerpts (some of them paraphrased), and the references that go with them:

  • "Similarly, mismatches in almost all adaptors, and even in "identical" adaptors of different manufacture, are readily measured on a high-frequency network analyzer such as the Hewlett-Packard 4195A (for additional wisdom and terror along these lines see Reference [1])." (p.16)
  • "Current probes are useful and convenient... See Reference [2]." (p.17)
  • "For an enjoyable stroll through the history of oscilloscope vertical amplifiers, see Reference [3]. See also Reference [41]." (p.20)
  • "See Reference [3] for history and wisdom about vertical amplifiers." (p.82)
  • "The protracted and intense development effort put toward [oscilloscopes] is perhaps equaled only by the fanaticism devoted to timekeeping. In particular, the marine chronometer received ferocious and abundant amounts of attention. See References [4,5,6]." (p.20)
  • "While the oscilloscope provides remarkable capability, its limitations must be well understood when interpreting results. Additional discourse on oscilloscopes will be found in References [1] and [7-11]." (p.24)
  • "By nature of its operation, a sampling scope in proper working order is inherently immune to input overload, providing essentially instantaneous recovery between samples. See Reference [8] for additional details." (p.24)
  • "Reticence to try things is probably the number one cause of breadboards that "don’t work". A much more eloquently stated version of this approach is found in Reference [12]." (p.27)
  • "There is no substitute for intimate familiarity with your tool's capabilities and limitations. Further exposition and kvetching on this point is given in Reference [13]." (p.31)
  • "The use of the lamp to control amplifier gain is a classic technique, first described by Meacham in 1938. See References [19,20,21]." (p.49)
  • "This method of generating fast pulses borrows heavily from the Tektronix type 111 Pretrigger Pulse Generator. See References [8] and [25]." (p.93)
  • "Figure 124 shows a simple, very fast sample-hold circuit... The Schottky bridge, similar to types used in sampling oscilloscopes (see References [7,8,28]) gives 1ns switching and eliminates the charge pump-through that a FET switch would contribute." (p.56)
  • "Figure 130 is an extremely versatile trigger circuit... [which] allows any point on the input waveform edge to be selected as the actual trigger point. This technique is borrowed from oscilloscope trigger circuitry, see Reference [29]." (p.58)
  • "Figure 137's economical wideband thermally based voltmeter is based on a monolithic thermal converter. The LT1223 provides gain, and drives the LT1088 RMS-DC thermal converter (complete details on this device and a discussion on thermal conversion considerations are found in Reference [40])." (p.61)
  • "This is why oscilloscope probes were developed, and why so much effort has been put into their development (Reference 42 is excellent)." (p.16)
  • "Emitter followers are notorious sources of oscillation and should never be directly driven from low impedance sources (see References [43] and [44])." (p.87)
  • "The circuit of Figure 132 allows very short pulsewidths (in this case 250ns full-scale) to be determined to a typical accuracy of 1%... Q3, aided by Baker (see Reference [45]) clamping, capacitive feedforward and optimized DC base biasing, turns off in a few nanoseconds." (pp.58-59)

A few other citations are scattered through the text: Figure 99 (on p.44) shows a high-speed analog multiplier, using the AD824, whose data sheet appears in Reference [26]. Settling-time measurements are discussed in Appendix B (see p.83). Jim's previous approach is described in [14]. (Also, did he mean to cite References [15,16] here?) The "Harvey Method" is described in [17]. The use of sampling oscilloscopes is described in [7,8,18]. Appendix H, in its discussion of current feedback, again touches on the Hewlett sine wave oscillator, which leads to References [19-24] and [46] (see p.124). He probably meant to cite [30] here, too.


No comments: