TCM4300 Datasheet, PDF (40/69 Pages) Texas Instruments – Advanced RF Cellular Telephone Interface Circuit (ARCTIC )

Modulation Error: In the digital mode, during the transmit burst, the complex output of the transmitter circuits
consists of an ideal output s = I _ideal + jQ_ideal + error e = e_i + je_q. In Table 4-5, the modulation error vector
magnitude (EVM) is defined as the peak value of the magnitude of e relative to the ideal output:
+ Modulation error percentage
100
|e|
|s|
%
Table 4–6 and Table 4–7 show the frequency response of the transmit section for digital and analog mode,
respectively.
Table 4–6. Transmit (TX) Channel Frequency Response (Digital Mode)
PARAMETER
TEST CONDITIONS
MIN TYP MAX UNIT
0 kHz to 8 kHz (see Note 4)
± 0.3
8 kHz to 15 kHz (see Note 4)
± 0.5
Frequency response
20 kHz to 45 kHz (see Note 2)
45 kHz to 75 kHz (see Note 2)
– 29
dB
– 55
> 75 kHz (see Note 2)
– 60
Any 30 kHz band centered at > 90 kHz (see Note 2)
– 60
Peak-to-peak group
delay distortion
0 kHz to 15 kHz
3 µs
Absolute channel delay 0 kHz to 15 kHz
NOTES: 2. Stopband
4. Deviation from ideal 0.35 SQRC response
320
µs
Table 4–7. Transmit (TX) Channel Frequency Response (Analog Mode)
PARAMETER
Frequency response
TEST CONDITIONS
0 kHz to 8 kHz (see Note 1)
8 kHz to 15 kHz (see Note 1)
20 kHz to 45 kHz (see Note 2)
45 kHz to 75 kHz (see Note 2)
> 75 kHz (see Note 2)
Any 30 kHz band centered at > 90 kHz (see Note 2)
MIN TYP MAX UNIT
± 0.5
± 0.5
– 31
dB
– 70
– 70
– 70
Peak-to-peak group
delay distortion
0 kHz to 15 kHz
3 µs
Absolute channel delay 0 kHz to 15 kHz
NOTES: 1. Ripple magnitude
2. Stopband
540
µs
4.4 Transmit Burst Operation (Digital Mode)
In the digital mode, the TCM4300 performs all encoding, signal processing, and power ramping for the burst.
Start and stop timing of the variable length bursts are set by means of the TXGO bit in the DStatCtrl
register. The SINT interrupt output interrupts the DSP at 48.6 kHz which is T/2 interval (T = 1 symbol
period = 1/24.3 kHz). The burst is initiated by the DSP writing 1 to 5 dibits to the TXI register, a small
positive-delay offset value d to the base station (BST) register, and a 1 to the TXGO bit in the DStatCtrl
register.
The TXGO bit is sampled on the falling edge of SINT. The transmit outputs are held at zero differential
voltage (each output terminal is held at the voltage supplied to the VCM input terminal) for 9.5 SINT periods
(195.5 µs) plus BST offset delay after SINT has detected TXGO high; then the transmit outputs begin to ramp
to the initial π /4 DQPSK constellation value. The shape of the ramp is the transient resulting from the internal
4–5