Filter
Top Products
9–8
AM700 Audio Measurement Set Service Manual
High Res
A/D
Circuit
High B/W
A/D
Circuit
To
Other
Channel
To
Other
Channel
Unity
Buffer
U45A (U57A)
Input
Clamps
4.2V
±
Input
Clamps
4.2V
±
CR26 – 33
Clamps
4.9V
±
CR24 – 27
VR5,VR6
Offset
Trim DAC
U81
Pin 3 (Pin 2)
Low Pass Filter
150 KHz, 3–Pole
Bessel
Minimal Phase Shift
at 20KHz
U60B (U59B)
U60A (U59A)
Single–Ended
to Differential
Converter
TP20 (TP22)
TP19 (TP21)
A A/D+ (B A/D+)
A A/D– (B A/D–)
FL11 (FL10)
Low Pass Filter
80KHz, 11–Pole
Elliptic
(Hybrid)
U122A (U122B)
Servo
CR42
CR41
To
Other
Channel
U123
Power–On
Hard
Clamp
to Ground
TP33 High BW B CH
R247
From
Other
Channel
TP34 High BW A CH
R248
0V DC 26
17
R252
Servo
MSB Adj.
R245
MSB Adj.
High BW
A/D 14 Bit Accuracy
(18 Bit “RESOLUTION”)
SAR
U81
Offset
Trim DAC
Pin 51 (Pin 24)
4
11
3
12
BBCLK
CONV
LDATA
RDATA
Data and Clock Lines
to Sample Transmitter PAL
8
13
9
10
U75
Digital
Decimation
Filter and Driver
(Decimate by 4)
12.288 MHz
25
23
12
17
DATAOUT
CLKOUT (3.072 MHz)
LRCLK
Decimated by 4
DATA + CLOCKS
12.288 MHz
R237
R340
Freq. Adj.
Y1
Clock
R274
19
U58
High Resolution
64X Oversampled
A/D
18 Bit
Effective Fs=48KHz
(Dual)∆Σ
3(26)
4(25)
10
9
15
13
14
AD CAL
CAL BUSY
SDATA
L/(R)
SCLK
(Control Lines)
CH A is Left CH of A/D
+15V
–15V
U61,U62
Regulator
TP27
TP35
TP36
+5A1
–5A1
Isolated for A/D
A Ground
Figure 9–4: Analog Acquisition A/D section CH 1 (CH 2)