韩式半永久上海佳●悦:英文翻译

If base-10 logarithms are chosen [log10(10) = 1 decade], with
decibels in mind, the slope voltage, VSLP, can be viewed in terms of
“volts-per-decade” in the scaling of the log of the voltage ratio.
Since there are 20 decibels in a decade, the corresponding
“volts/dB” is just one-twentieth of this voltage. Thus, for a VSLP of
400 mV/decade, the slope can also be expressed as 20 mV/dB.
The second scaling parameter, called the “intercept,” VINT, is the
input voltage at which the log argument is unity. At this voltage,
independent of choice of base, the output would be zero, since
log(1) = 0. In practice, the finite available gain in an RF log amp,
the presence of noise, and other practical limitations result in a
value for VINT that is an extrapolated value, typically only a few
microvolts, and fixed by the design.
A question then arises as to the precise interpretation of what VINT
represents. Is this quantity “volts dc,” or perhaps “volts rms”? Or
is it some other metric, such as a simple average value, or the peak
value? For measurements of ratios from one level to another, the
value of VINT is unimportant. However, where it is required to
determine the absolute level of VSIG, the measurement accuracy
depends directly on the value of VINT in just the same way as a
reference voltage in, say, a DVM.
A close study of RF logarithmic amplifiers, which use the
technique1 known as “progressive compression,” shows another
effect not encountered in classical log amp practice, namely, that
the effective value of VINT strongly depends on the waveform of the
input signal. For that reason, we choose to define VINT for a
sinusoidal input, and then provide conversion factors for various
other waveforms.