ULA1145

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

7 of 10

www.unisonic.com.tw

QW-R106-006.a



SD OUTPUT CIRCUIT

1.

Hole detector

Signal meter

Bandmute

Comparator

18

Exhibit hysteresis

Mute driver

19 SD output

16

As shown, the SD output is the logical AND of the band mute and S-meter comparator outputs.

2. Signal search using the SD output circuit

2-1 The transition response characteristics of the SD output circuit depends on the time constants of pins 16, 17, 18

and 9.

As the SD output transition response characteristics are determined by the pin with the largest time constant,

erroneous stopping will result when a search time is less than the largest one.

2-2 Band mute range circuit time constant (pin 9)

An equivalent circuit to the band circuit is shown below.

9

12

C

Mute switch circuit