TCM4400 Datasheet, PDF (19/72 Pages) Texas Instruments – GSM/DCS BASEBAND AND VOICE A/D AND D/A RF INTERFACE CIRCUIT

2.4.4 dc Accuracy – Baseband Downlink Path
PARAMETER
Offset error before calibration†
Offset error after calibration
TEST CONDITIONS
± 21 on 16-bit I and Q words†
MIN TYP
– 60
0
–2
0
MAX
60
2
UNIT
LSB
LSB
Offset correction range
full scale
† _{The LSB corresponds to the one of the ADC which is specified with 66-dB dynamic range (± 1024), which means 11-bit,}
but the output data bits are transmitted through the serial interface with 16-bit words. The decimation ratio of 24 (6.5
MHz/270 kHz) makes the maximum code on a 16-bit word 21060 instead of 32767. Therefore, one LSB of the ADC
corresponds to a value of 21060/1024 = 20.57 on the 16-bit output serial words on I and Q.
2.5 Channel Characteristics
2.5.1 Frequency Response – Baseband Downlink Path
PARAMETER
MIN TYP MAX UNIT
< 0 Hz
– 0.2
0.2
67.5 kHz
– 0.3
0.25
Frequency response of the total path with values
referenced to 18 kHz
96 kHz
135 kHz
–4
0.3
dB
– 40
200 kHz
– 40
400 kHz
– 40
2.5.2 SNR vs Signal Level-baseband Downlink Path
PARAMETER
TEST CONDITIONS
– 45 dBm0
200-kHz bandwidth
– 40 dBm0
– 30 dBm0
Signal level
– 20 dBm0
– 10 dBm0
– 3 dBm0
0 dBm0
Idle channel noise, 0 Hz – 200 kHz
MIN TYP MAX UNIT
21
26
36
46
dB
50
57
30
– 66 dBm0
2.5.3 Gain Characteristics of the Baseband Downlink Path
PARAMETER
TEST CONDITIONS MIN
Absolute gain error relative to VVREF
at –10 dBm0 and
18 kHz
–11
3 dBm0
– 0.25
0 dBm0
– 0.25
Gain tracking error over the range 3 dBm0
to – 50 dBm0 at 18 kHz with reference
–10 dBm0
– 5 dBm0
– 10 dBm0
– 20 dBm0
– 30 dBm0
Reference level
– 0.25
– 0.25
– 0.25
– 0.25
– 40 dBm0
– 0.25
– 50 dBm0
– 0.50
TYP MAX UNIT
–10 – 9 dB
0.25
0.25
0.25
0.25
dB
0.25
0.25
0.25
0.50
2.5.4 Group Delay – Baseband Downlink Path
PARAMETER
Group delay
0 Hz to 100 kHz
MIN TYP MAX UNIT
28
µs
2–5