10

9136C–INDCO–10/09

ATA8404/ATA8405 [Preliminary]

The output capacitance of 0.66 pF will be absorbed into the load impedance, so a real imped-

ance of 684

Ω (ATA8404) at 315 MHz and 623Ω (ATA8405) at 433.92 MHz should be

measured with a network analyses at pin 5 (ANT1) with the ATA8404/ATA8405 soldered, an

optimized antenna connected, and the power amplifier switched off.

Less output power is achieved by lowering the real parallel part where the parallel imaginary

part should be kept constant. Lowering the real part of the load impedance also reduces the

supply voltage dependency of the output power.

Output power measurement can be done with the circuit as shown in Figure 4-6. Please note

that the component values must be changed to compensate for the individual board parasitics

until the ATA8404/ATA8405 has the right load impedance. Also, the damping of the cable used

to measure the output power must be calibrated.

Figure 4-6.

Output Power Measurement ATA8404/ATA8405

Table 4-2 and Table 4-3 show the output power and the supply current versus temperature

and supply voltage.

Table 4-2.

Output Power and Supply Current versus Temperature and Supply

Voltage for the ATA8404 with Z

Ambient

Temperature

V

(dBm/mA)

V

(dBm/mA)

V

(dBm/mA)

3.1 ±1.5 / 7.2

6.1 +2/–3 / 7.7

7.1 +2/–3 / 7.9

T

3.0 ±1.5 / 7.5

6.0 ±2 / 8.1

7.4 ±2 / 8.3

3.0 ±1.5 / 7.5

5.8 +2/–3 / 8.2

7.2 +2/–3 / 8.5

Table 4-3.

Output Power and Supply Current versus Temperature and Supply

Voltage for the ATA8405 with Z

Ambient

Temperature

V

(dBm/mA)

V

(dBm/mA)

V

(dBm/mA)

3.3 ±1.5 / 7.6

6.2 +2/–3 / 8.1

7.1 +2/–3 / 8.4

3.0 ±1.5 / 8.0

6.0 ±2 / 8.5

7.5 ±2 / 8.8

2.8 ±1.5 / 8.0

5.7 +2/–3 / 8.6

6.8 +2/–3 / 8.8

~

ANT2

ANT1

Power

meter

Z

Lopt

Z = 50

Ω

50

Ω