Analog ICs contain circuits that don’t normally
operate in saturation or cutoff. The operational
amplifier presented in Chap. 9 is a prime example. The voltage regulator shown earlier in this
chapter is another. Analog ICs include:
• Audio amplifiers
• RF and IF amplifiers (radio frequency
and intermediate frequency)
• Modulators and mixers (used in
communications)
• Operational amplifiers
• Instrumentation amplifiers (precision op
amps)
• Voltage regulators
The 555 timer IC presented in the previous
section fits into a category called mixed signal
ICs. These contain or use both digital and analog functions. Additional mixed signal ICs are
presented in the next section of this chapter.
Figure 13-22 on page 400 shows the National
Semiconductor LM3876 audio power amplifier.
It is housed in a plastic package and can
provide up to 56 W of power to an 8- speaker.
Its total harmonic distortion is less than one tenth of one percent and its signal to noise ratio
is 95 dB or better, so it qualifies for use in component stereo and home theater applications.
It is both over-voltage and short-circuit protected. As the schematic shows, its use requires
only a few external parts. Considering the
low cost of this IC, few designers would consider a discrete design if this device would
serve instead.