HD155111F Datasheet, PDF (12/44 Pages) Hitachi Semiconductor – RF Single-chip Linear IC for PCN Cellular Systems

HD155111F
IFVCO Operation
The HD155111F incorporates an IFVCO circuit. The IFVCO circuit consists of an IFVCO transistor and a
bias circuit for it, whose current are 2.0 mA and 0.5 mA respectively. If an internal IFVCO is used, treat
pin 23 (IFVCOO), pin 24 (IFVCOI) and pin 21 (IFLO) as shown figure 3-(a).
Using an external IFVCO, pin 23 (IFVCOO) and pin 24 (IFVCOI) cannot be connected any pattern and
component, and any component to feed direct current must be also removed from pin 21 (IFLO).
If pin 23 (IFVCOO), pin 24 (IFVCOI) and pin 21 (IFLO) are treated as shown figure 3-(b), current
consumption will decrease 2.0 mA.
Moreover, there is the other external IFVCO solution using only an IFVCO bias circuit as shown figure 3-
(c). The IFVCO bias circuit has an internal power save function. Therefore, if figure 3-(c) is adopted, an
internal power save function can be used as well as figure 3-(a).
IFVCO
bias circuit
21 23 24 ^HD155111F
IFVCO
bias circuit
21 23 24 ^HD155111F
Vtune
Vcc
PLL
IFLO ^synth.
(a) using an internal IFVCO
External
IFVCO
Vtune
PLL
IFLO ^synth.
(b) using an external IFVCO
IFVCO
bias circuit
21 23 24 ^HD155111F
Vtune
PLL
Vcc
IFLO ^synth.
(c) using only an IFVCO bias circuit
Figure 3 IFVCO Circuits