+14dBm to +20dBm LO Buffers/Splitters
with 1dB ꢀariation
Table 1. External Resistor Values for +14dBm to +20dBm Output Power
NOMINAL
OUTPUT POWER
(dBm)
MAX9987
INPUT DRIVE
(dBm)
MAX9988
INPUT DRIVE
(dBm)
R (Ω)
1
R (Ω)
2
R (Ω)
4
R (Ω)
5
+20
+19
+18
+17
+16
+15
+14
1.35k
2.2k
2.0k
3.0k
Open
Open
Open
Open
1.8k
Open
Open
Open
Open
3.0k
10
9
3
12
11
10
9
3
3
3
3
5.0k
6.0k
8
3
3
3
3
3
Open
Open
Open
Open
Open
Open
Open
Open
7
3
6
8
3
3
3
0.9k
1.1k
5
7
0.6k
0.6k
4
6
Applications Information
Table 2. Component Values for Typical
Application Circuit
Input and Output Matching
All input and output matching is accomplished on-chip;
no external matching circuitry is required. Use a DC
block of about 47pF (lowband) or 22pF (highband) at
the input and the outputs. Because these parts are
internally broadband matched, adjusting external com-
ponent values can optimize performance for a particu-
lar band.
COMPONENT VALUE
DESIGNATION
MAX9987
MAX9988
(LOWBAND)
(HIGHBAND)
C1, C3, C6
100pF
100nF
C2, C4, C5, C7, C8,
C9, C12, C13, C14
47pF
22pF
Input Drive Level
In the case of the MAX9987, the typical required input
drive level is +7dBm for +17dBm output, or +10dBm for
+20dBm output. The MAX9988 uses slightly higher
input levels (see Table 1). The typical VCO cannot pro-
vide sufficient drive by itself; the typical application fol-
lows the VCO with attenuation (about +3dB), and then
with a low-noise gain block. This allows the VCO to
drive the MAX9987/MAX9988 input at the required level
without being load-pulled.
C10, C11
R1, R2, R4, R5
R3
5pF
See Table 1.
100Ω
10pF
See Table 1.
100Ω
Driver Amplifiers and Outputs
Each of the output amplifiers are similar to the input
amplifier, except they are biased higher to provide more
output power. For example, with an input power of
+10dBm, the MAX9987 can deliver +20dBm at both out-
puts. The bias is adjustable; see Table 1 for details.
Output Drive Level
The output drive of the MAX9987/MAX9988 is nominally
+17dBm 1dB. This is the typical application, with no
external bias-setting resistors at INBIAS and OUTBIAS.
Output power can be set from +14dBm to +20dBm by
using the bias-setting resistor values listed in Table 1.
Both RF outputs are internally matched to 50Ω, with a
typical VSWR limit of 2:1. Provide DC blocking capaci-
tors at the outputs.
Chip Information
TRANSISTOR COUNT: 89
PROCESS: BiCMOS
10 ______________________________________________________________________________________