Table 1. MAX2242 Output Power and Supply Current
(Input Power = 0dBm)
MAX2242 1.9GHz DECT Output Power vs Input Power
Figure 1. MAX2242 1.9GHz DECT output power versus input power.
The MAX2242 PA uses a 3-stage amplifier design and requires input, interstage and output matching components for optimum performance. Refer to Figure 2 for a schematic of the required matching components. Because the input of the PA is internally biased, a DC-Block is required at the input of the device. A two-element LC match optimizes the input return loss for 1.9GHz. A small amount of series inductance is required on VCC1 and VCC2 to optimize the matching between stages. For VCC1, this is accomplished with a series 1.8nH inductor, and a short length of transmission line. For VCC2, this is accomplished with a short length of transmission line. The output stage requires a pull-up inductor for DC bias. A series-L and a shunt-C are required for optimizing the output power to the load. The series-L element is achieved with a short length of transmission line and a series 0W which provides approximately 0.5nH of inductance. The exact amount of inductance for the interstage and output matching will vary with your board layout, board thickness and dielectric constant. Refer to Figure 2 for component values and Figure 3 for the location of the VCC1, VCC2 bypass capacitors and the output shunt capacitor that sets the amount of inductance for these traces on the MAX2242 EV kit.
The MAX2242 EV kit is available for purchase, and the layout files for the MAX2242 EV kit are available by request.
Figure 2. MAX2242 1.9GHz DECT schematic.
Figure 3. MAX2242 1.9GHz DECT EV kit component locations.