MAX7058 Evaluation Kit
Evaluates: MAX7058
Power Supply
The MAX7058 operates from a 2.1V to 3.6V supply.
Apply an external voltage up to 3.6V between the VDD
and GND pads. VDD by default powers DVDD, AVDD,
and PAVDD.
Layout Issues
A properly designed PCB is essential for any RF/micro-
wave circuit. Keep high-frequency input and output lines
as short as possible to minimize losses and radiation. At
high frequencies, trace lengths that are on the order of
λ/10 or longer can act as antennas.
DVDD, AVDD, and PAVDD
DVDD, AVDD, and PAVDD are powered by VDD by
default. To apply an external voltage to DVDD, change
the shunt on jumper JU1 to the 2-3 position and apply
an external voltage on TP1. To apply an external volt-
age to AVDD, change the shunt on jumper JU5 to the
2-3 position and apply an external voltage on TP6. To
apply an external voltage to PAVDD, change the shunt
on jumper JU6 to the 2-3 position and apply an external
voltage on TP7.
Both parasitic inductance and capacitance are influ-
ential on circuit layouts and are best avoided by using
short trace lengths. Generally, a 10-mil wide PCB trace,
0.0625in above a ground plane, with FR4 dielectric has
about 19nH/in of inductance and about 1pF/in of capaci-
tance. In the matching network, where the inductor is
on the order of 22nH and a capacitor is on the order of
10pF, the proximity of the circuit to the MAX7058 has a
strong influence on the effective component values.
External Frequency Input
For applications where an external frequency is desired
over the crystal frequency, it is possible to apply an
external frequency through REFIN. Capacitors C14 and
C15 are necessary (use a 100pF capacitor and remove
the Y1 crystal). The MAX7058 operates by multiply-
ing the crystal frequency to the necessary RF carrier
frequency. When FSEL is low, the crystal frequency is
multiplied by 26 (390MHz) and when FSEL is high, the
multiplication is 21 (315MHz). Changing the frequency to
a different value would result in different carrier frequen-
cies and components not matching the required imped-
ance characteristics.
To reduce the parasitic inductance, use a solid ground
or power plane below the signal traces. Also, use low-
inductance connections to ground on all GND pins,
and place decoupling capacitors close to all VDD
connections.
Detailed Description of Hardware
The MAX7058 EV kit provides a proven layout for the
MAX7058. On-board test points are included to monitor
various signals and to provide power (Table 3).
Table 3. Test Points
TP
1
DESCRIPTION
External DVDD supply
2
No connection (not populated)
DIN input
3
4
ENABLE input
TOGGLE input
External AVDD supply
External PAVDD supply
CAP4 input
5
6
7
8
9
CAP3 input
10
11
12
CAP2 input
CAP1 input
FSEL input
4
Maxim Integrated
