ATA5773-DK1 Atmel, ATA5773-DK1 Datasheet - Page 10

• Manufacturer Part Number: ATA5773-DK1
• Description: BOARD XMITTER FOR ATA5773 315MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5773-DK1

• Frequency: 315MHz
• Maximum Frequency: 315 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 9 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5773
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

10
Atmel ATA5771/73/74
The load impedance is defined as the impedance seen from the power amplifier (pin ANT1
and pin ANT2) into the matching network. This large signal load impedance should not be
mixed up with the small signal input impedance delivered as input characteristic of RF amplifi-
ers and measured from the application into the IC, instead of from the IC into the application.
Please take note that there must be a low resistive path between the V
put of the PA to deliver the DC current. Reduced output power will be achieved by lowering the
real parallel part of the load impedance where the parallel imaginary part should be kept
constant.
Output power measurement can be performed using the circuit shown in
the component values must be changed to compensate for the individual board parasitics until
the RF power amplifier has the right load impedance. In addition, the damping of the cable
used to measure the output power must be calibrated out.
Figure 3-2.
• Z
Load
– Background: The current pulse of the power amplifier is 7.7mA and the maximum
output power is delivered to a resistive load of 475 if the 0.53pF output
capacitance of the power amplifier is compensated by the load impedance. And
thus the load impedance of Z
is achieved for the maximum output power of 5.5dBm.
= (166 + j226) for the Atmel ATA5771 with the power efficiency of 24%
Output Power Measurement Atmel ATA5771/73/74
ANT1
ANT2
Z
Lopt
C
V
L
Load
1
S
1
= 1 nF
= 47 nH
C
2
= 475 || j/(2
= 3.3 pF
Z = 50
f
0.53 pF) = (166 + j226)
Power
meter
50
R
S
in
and the collector out-
Figure
3-2. Note that
9137E–RKE–12/10