Errata, Chapter 5, EMRFD
p 5.4, left column 2.5 inch up from text bottom: Replace the word
"average" with "mean." (21March10)
p5.7, left column, 3 lines up from bottom:
replace "extracted form" with "extracted from"
P5.7, Fig 5.17 caption. Add sentences:
“The circuit in C offers good suppression but poor gain. See text.”
p5.7, middle column.
Replace the two paragraphs beginning 0.4 inches down from text
top extending to 2.0
inches down from text top with:
"Although suppression has been improved in
the circuit of Fig 5.17 C, the topology has canceled the desired
IF output. The designer/builder
must exercise care to guarantee that the addition of balance will
eliminate the mixing action. " (2June04)
p5.7, middle column, 2.1 inches
down from text top. Replace "A variation of the ..." with
variation of the ....."
p 5.8, left column, 1.8 inch down from text top: Change the
difference expression (Frf-Fif) to a product (Frf*Fif). (21March10)
p5.11, Fig 5.26, caption: replace Phillips
with Philips. (This is an error that must surely be present
elsewhere. Our apologies to Philips!) 4 May 04
col. second line from top. Replace "to measured
DSB" with "to measure DSB" (3Dec03)
p 5.15, middle column, 3.5 inches down from top of text. Add a sentence
right after TUF-1 and SBL-1. The sentence should be: "Additional
information on mixer operating levels is found in the discussion of phasing
transmitters in Chapter 9." (10March11)
p5.17, left column, top of text: replace "there
also be" with "there can be" (9Dec03)
p5.18, Fig 5.46 and related discussion: This is informational and there is no error that needs fixing.
HC series flip-flops are used in several places throughout
EMRFD as frequency dividers to generate square waves that then provide
harmonic outputs. In this discussion we used some really
old data suggesting that the output impedance of a CMOS part was around
1K. That was the end resistance used for filter design. We
recently did some measurements with a HC inverter where a variety of loads
were placed on the part. I measured an output R of 39 Ohms for a single
gate. This drastic difference means that the bandpass filter
will have different components and should be redesigned accordingly.
There is no need to change any of the example circuits, for they were all
checked with a spectrum analyzer when they were constructed.
There can be a problem with this low impedance:
When we see a low value, we might be tempted to think that we can
do an impedance match to this value and extract a lot of power.
That is probably not true, for there could be stability problems.
Heavily loading the HC output could cause high currents to flow internally
in the IC, causing it to exceed power ratings. A heat sink would
then be required. Loading will usually be light when using
the chips for frequency multipliers, for the usual bandpass filter will
attach to the IC with a small series capacitor. This will present
a low impedance at the harmonic, but a relatively high Z at the fundamental.
The IC will not be heavily loaded by such a circuit.
An ideal way to design might be to place a 220 Ohm resistor in series
with the output. The composite output impedance would then be about
250 Ohms. If this value is used for filter design, the result would
be worst case 500 Ohm load on the IC which should not cause problems.
p5.21. right column, 2.1
inches down from text top. Change subtly to subtlety.
(8 July 03)
8. Chris Trask informs us that he did not write
this early data sheet for the NE-602. The data sheet
in my files has no listed author, but I'm pretty sure it
was Bob Zavrel, W7SX, for he did much of the early Signetics
applications work on that part. That was an era when application notes just appeared
from the mist and didn't need anyone to write them. (24Feb03) (This has NOT been confirmed with W7SX.)