How do you build a pager receiver that has
both small size and excellent performance?
Figure 13-23 on page 401 shows the Sony
CXA3176N integrated circuit that was designed for such an application. The 24-pin
SSOP is only 7.8 mm 5.6 mm 1.25 mm
(0.307 in. 0.22 in 0.05) yet holds most of
what is needed for a dual-conversion, superheterodyne receiver. To build a complete
receiver, a first mixer and first local oscillator
are required, as these functions are not on the
chip. Also, the receiver will need an external
crystal to control the second local oscillator, a 450-kHz ceramic IF filter, a ceramic resonator for the quadrature detector, and a modest number of resistors and capacitors. In addition to basic receiver functions, the chip
also provides AFC (automatic frequency
control), RSSI (received signal strength indicator), on-chip voltage regulation, and a
battery saving mode.