Datasheet

MAX9989/MAX9990
+14dBm to +20dBm LO Buffers
with ±1dB Variation
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Output Amplifier
The output amplifier is similar to the input amplifier,
except it is biased higher to provide more output power.
For example, with an input power of +10dBm, the
MAX9989 can deliver +20dBm. The bias is adjustable;
see Table 1 for details.
The RF output is internally matched to 50Ω, with a typi-
cal VSWR limit of 2:1. Provide DC-blocking capacitors
at the outputs.
Applications Information
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 (low band) or 22pF (high band) 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.
Input Drive Level
In the case of the MAX9989, the typical required input
drive level is +7dBm for +17dBm output, or +10dBm for
+20dBm output. The MAX9990 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 MAX9989/MAX9990 input at the required level
without being load-pulled.
Output Drive Level
The output drive of the MAX9989/MAX9990 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.
Chip Information
TRANSISTOR COUNT: 89
PROCESS: BiCMOS
Table 1. External Resistor Values for +14dBm to +20dBm Output Power
NOMINAL
OUTPUT POWER
(dBm)
R2 (kΩ) R4 (kΩ) R3 (kΩ) R5 (kΩ)
MAX9989
INPUT DRIVE
(dBm)
MAX9990
INPUT DRIVE
(dBm)
+20 1.35 Open 2.0 Open 10 ±3 12 ±3
+19 2.2 Open 3.0 Open 9 ±3 11 ±3
+18 5.0 Open 6.0 Open 8 ±3 10 ±3
+17 Open Open Open Open 7 ±3 9 ±3
+16 Open 1.8 Open 3.0 6 ±3 8 ±3
+15 Open 0.9 Open 1.1 5 ±3 7 ±3
+14 Open 0.6 Open 0.6 4 ±3 6 ±3
Table 2. Component Values for Typical
Application Circuit
COMPONENT VALUE
DESIGNATION
MAX9989
(LOWBAND)
MAX9990
(HIGHBAND)
C1, C2, C4, C6, C8,
C9, C10
47pF 22pF
C3, C7, C11 0.1µF 0.1µF
C5 5pF 22pF
R2–R5 See Table 1 See Table 1
R1 100Ω 100Ω