.

Pin 5 is the output pin. The output from Pin 5 is input to the

SIF via a 6 MHz bandpass filter (BPF).

When 5.5 MHz is input to Pin 1, the spectrum shown in

Figure 10 is obtained at Pin 5. Even if there is a 5.85 MHz

NICAM signal, the D/U (desirable/undesirable) ratio at Pin 5

increases and the buzz characteristic does not deteriorate.

When 6 MHz is input at Pin 1 and there is a 6.552 MHz

NICAM signal, then 6.552 MHz is mixed with 500 kHz to

make 6.052 MHz. This becomes an interference signal and is

within the band for 6 MHz. Therefore,for 6 MHz input, Pin 4

is grounded with 10 k

Ω to stop the oscillation and pass

through the input signal 6 MHz as is.

Reference Characteristic Diagram

Unit (resistance:

Ω)

Figure 9

Output level

Ceramic BPF

chracteristic

D/U ratio

Figure 10 (5.5 MHz input)

Output level

Interference obtained with LA7975 mixer

6.552 MHz – 500 kHz = 6.052 MHz

D/U

ratio

Figure 11 (6 MHz input)

Input/output characteristic

Input level – dB/µV

* S1 on for 6 MHz

measurement

Unit (resistance:

Ω, capacitance: F)

* Input level 80 dB/µV S1 on

for 6 MHz measurement

LA7975

No.3994-5/6