AD8315
Using the Chip Scale Package
C1
R2
TP1
0.1ꢁF
52.3ꢀ
On the underside of the chip scale package, there is an exposed
paddle. This paddle is internally connected to the chip’s ground.
There is no thermal requirement to solder the paddle down to the
printed circuit board’s ground plane. However, soldering down
the paddle has been shown to increase the stability over frequency
of the AD8315 ACP’s response at low input power levels (i.e., at
R1
AD8315
J1
J3
0ꢀ
1
8
7
RFIN
RFIN
VPOS
VAPC
NC
V
POS
R3
J2
VPOS
SW1
0ꢀ
2
3
4
ENBL
VSET
FLTR
VAPC
R4
(OPEN)
C2
(OPEN)
VSET
6
5
TP2
around –45 dBm) in the DCS and PCS bands
.
COMM
C4
(OPEN)
Evaluation Board
NC = NO CONNECT
Figure 11 shows the schematic of the AD8315 MSOP evaluation
board. The layout and silkscreen of the component side are
shown in Figures 12 and 13. An evaluation board is also available
for the LFCSP package (for exact part numbers, see Ordering
Guide). Apart from the slightly smaller device footprint, the
LFCSP evaluation board is identical to the MSOP board. The
board is powered by a single supply in the range, 2.7 V to 5.5 V.
The power supply is decoupled by a single 0.1 F capacitor.
Table II details the various configuration options of the
evaluation board.
LK1
LK2
V
POS
C3
0.1ꢁF
C5
0.1ꢁF
R8
R7
10kꢀ
16.2kꢀ
AD8031
R6
17.8kꢀ
R5
10kꢀ
Figure 11. Evaluation Board Schematic
Table II. Evaluation Board Configuration Options
Component
Function
Default Condition
TP1, TP2
SW1
Supply and Ground Vector Pins
Not Applicable
SW1 = A
Device Enable: When in Position A, the ENBL pin is connected to VPOS and
the AD8315 is in operating mode. In Position B, the ENBL pin is grounded
putting the device in power-down mode.
R1, R2
Input Interface: The 52.3 W resistor in Position R2 combines with the
AD8315’s internal input impedance to give a broadband input impedance
of around 50 W. A reactive match can be implemented by replacing R2 with
an inductor and R1 (0 W) with a capacitor. Note that the AD8315’s RF input
is internally ac-coupled.
R2 = 52.3 W (Size 0603)
R1 = 0 W (Size 0402)
R3, R4, C2
C1
Output Interface: R4 and C2 can be used to check the response of VAPC to
capacitive and resistive loading. R3/R4 can be used to reduce the slope of VAPC
Power Supply Decoupling: The nominal supply decoupling consists of a
R4 = C2 = Open (Size 0603)
R3 = 0 W (Size 0603)
.
C1 = 0.1 mF (Size 0603)
C4 = Open (Size 0603)
LK1, LK2 = Installed
0.1 mF capacitor.
C4
Filter Capacitor: The response time of VAPC can be modified by placing a
capacitor between FLTR (Pin 4) and ground.
Measurement Mode: A quasi-measurement mode can be implemented by
installing LK1 and LK2 (connecting an inverted VAPC to VSET) to yield the
nominal relationship between RFIN and VSET. In this mode, a large capacitor
(0.01 mF or greater) must be installed in C4.
LK1, LK2
REV. B
–15–
ADI [ ADI ]
