MAX9989ETP-T Maxim Integrated Products, MAX9989ETP-T Datasheet - Page 8

• Manufacturer Part Number: MAX9989ETP-T
• Description: RF Amplifier +14dBm to +20dBm LO Buffers with +/-1dB
• Manufacturer: Maxim Integrated Products

The MAX9989/MAX9990 LO buffers each consist of a
single-input amplifier, an output amplifier, and a second
buffer amplifier to drive the LO’s PLL. The bias currents
for the amplifiers are adjustable through off-chip resis-
tors, allowing the output level to be precision set any-
where from +14dBm to +20dBm. The PLL output is
preset to +3dBm (about 900mV
Power levels are typically ±1dB over the full supply, input
power, and temperature range. Precision power control
is achieved by internal control circuitry. Maintaining tight
power control keeps the system engineer from over
specifying the LO drive in order to guarantee a linearity
specification in the base-station mixer. More than 40dB
isolation between the LO output and the input prevents
VCO pulling.
The MAX9989 is specified from 700MHz to 1100MHz,
and the MAX9990 is specified from 1500MHz to
2200MHz. Both are offered in compact 5mm
pin QFN thin packages with EP.
+14dBm to +20dBm LO Buffers
with ±1dB Variation
8
13–18, EP
1, 4, 8, 9,
_______________________________________________________________________________________
11, 12
PIN
10
19
20
2
3
5
6
7
BIASOUT
VCCREF
OUTPLL
OUTLO
BIASIN
NAME
VCC1
VCC2
GND
REF
IN
Detailed Description
Ground. Provide 5–10 plated vias from EP to system ground plane for optimal thermal and RF
performance.
Input. Internally matched 50Ω RF input. AC couple to this pin so as not to disturb input bias level.
Supply. Supply connection for on-chip voltage and current references. See Applications Information
for information on decoupling.
Voltage Reference Output. Output for on-chip 1.5V bandgap voltage reference. See the
Applications Information section for information on decoupling.
Bias Connection for Input Buffer. Set compressed power point for input amplifier with a resistor to
REF or GND. For +17dBm output power, no external biasing resistors are required. See the
Applications Information section for more information.
Bias Connection for LO Output Amplifier. Set compressed power point for OUTLO with a resistor to
REF or ground. For +17dBm output power, no external biasing resistors are required. See the
Applications Information section for more information.
LO Output. Internally matched 50Ω RF output. AC couple to this pin so as not to disturb output bias
level.
Supply. Supply connection for OUTLO.
Supply. Supply connection for input amplifier.
PLL Output. Output for driving optional external PLL. Requires external 100Ω pullup to V
For applications not requiring the PLL driver, removing R1 leaves OUTPLL unbiased, saving about
12mA current.
P-P
into 50Ω).
✕
5mm 20-
A single low-noise input amplifier provides gain and iso-
lation. The compressed output power for this stage is
controlled by the bias setting resistors R2 or R4 (see the
Typical Application Circuit). These resistors are not
required for the nominal +17dBm output; see Table 1 for
bias resistor values to obtain +14dBm to +20dBm out-
put power.
The input is internally matched to 50Ω, and typical
VSWR is no more than 2:1 over all operating conditions.
Since the input is internally biased, provide a DC block
at the input pin.
A small amount of power is tapped off from the input
amplifier’s output, and fed to a high-isolation buffer to
drive the PLL output at about +3dBm. If the PLL output
is not required, it can be disabled by removing R1; dis-
abling the PLL output saves 12mA supply current.
FUNCTION
PLL Amplifier and Output
Pin Description
Input Amplifier
CC
for bias.