cxa2511aq Sony Electronics, cxa2511aq Datasheet - Page 15

• Manufacturer Part Number: cxa2511aq
• Description: Dolby B-c Type Noise Reduction System With Playback Equalizer Amplifier
• Manufacturer: Sony Electronics

3. Playback equalizer amplifier
The CXA2511AQ achieves the frequency response of Fig.4 with the circuit configuration shown in Fig. 3.
Two systems (FORWARD and REVERSE) of playback head input are provided for each channel.
The FORWARD input pin is selected when DRSW (Pin 19) is Low; REVERSE is selected when DRSW is
High.
The playback equalizer amplifier frequency response can be set in two levels.
When TAPESW (Pin 18) is Low, SW2 shown in Fig. 3 is turned OFF; when TAPESW is High, SW2 is turned
ON.
The external resistance R1 should be adjusted to adjust the playback equalizer amplifier gain.
The playback equalizer amplifier frequency response is all determined by the external resistance and
capacitance, and it can be obtained with the following equation.
Using the above equation, G1 in Fig. 3 and low-frequency time constant (T1) and high-frequency time
constants (T2 and T3) are as follows:
Fig. 3. Playback equalizer amplifier
PB IN
PBREF
FWD
RVS
G (s) =
Where, Rx = R3 when TAPESW pin =Low;
G1 = 20log
T1 = C1 · (R2 + Rx)
T2, T3 =
block diagram
PBFB
R1
SW1
Rx = R3//R4 when TAPESW pin = High
R1 + R2
C1 · (R1 · R2 + R2 · Rx + Rx · R1)
R1
R1 + R2
C1
AMP1
R1
70µs
·
PBEQ
SW2
R4
1 + {s · C1 · (R1 · R2 + R2 · Rx + Rx · R1) / (R1 + R2)}
R3
R2
R1 + R2
PBOUT
1 + s · C1 · (R2 + Rx)
Gain (dB)
G1
– 15 –
Fig. 4. Playback equalizer amplifier
frequency response
f1
T1
–6dB/oct
(s = j )
f2
f3
T2
T3
Frequency [Hz]
CXA2511AQ