max2058etlt Maxim Integrated Products, Inc., max2058etlt Datasheet - Page 12

• Manufacturer Part Number: max2058etlt
• Description: Max2058 700mhz To 1200mhz High-linearity, Spi-controlled Dvga With Integrated Loopback Mixer
• Manufacturer: Maxim Integrated Products, Inc.

The MAX2058 high-linearity DVGA consists of two 5-bit,
31dB digital attenuators, a fixed-gain two-stage driver
amplifier, a loopback mixer, and a serial interface to
control the attenuators. This high level of component
integration makes the MAX2058 ideal for base-station
transmitter applications. The MAX2058 is designed to
operate in the 700MHz to 1200MHz frequency ranges.
The overall cascaded performance of the MAX2058
produces a typical 10.5dB gain, a +32.3dBm OIP3, a
19dBm OP1dB, and a total 62dB gain-control range.
The MAX2058 integrates two 5-bit digital attenuators to
achieve a high dynamic range. Each attenuator has a
31dB control range, a 1dB step size, and is pro-
grammed with the 3-wire SPI. See the Applications
Information section and Table 1 for attenuator program-
ming details. The attenuators can be used for both stat-
ic and dynamic power control.
700MHz to 1200MHz High-Linearity,
SPI-Controlled DVGA with Integrated Loopback Mixer
Table 1. Attenuator Programming
Figure 1. SPI Timing Diagram
12
CLOCK
DATA
ATTENUATOR A (5 MSBs)
CS
______________________________________________________________________________________
MSB
NOTES:
DATA ENTERED ON CLOCK RISING EDGE.
ATTENUATOR STATE CHANGE ON CS RISING EDGE.
Bit 9 = 16dB step
Bit 8 = 8dB step
Bit 7 = 4dB step
Bit 6 = 2dB step
Bit 5 = 1dB step
BIT 9
BIT 8
t
CS
Detailed Description
t
EWN
ATTENUATOR B (5 LSBs)
5-Bit Attenuators
Bit 4 = 16dB step
BIT 1
Bit 3 = 8dB step
Bit 2 = 4dB step
Bit 1 = 2dB step
Bit 0 = 1dB step
t
CH
BIT 0
t
CW
t
ES
LSB
t
EW
The MAX2058 includes a two-stage medium power
amplifier with a fixed 17.5dB gain. The driver amplifier
circuit is optimized for high linearity and medium output
power capability for the 800MHz to 1000MHz frequen-
cy range. The driver amplifier is intended to amplify a
modulated signal and drive a high-power amplifier in
base-station transmitters. In a typical application, the
driver amplifier is cascaded in between the two digital
attenuators. See the Typical Application Circuit.
The two-stage amplifier stage can be disabled for
applications where only the digital attenuators and/or
loopback mixer are used. To disable the two-stage
amplifier, ground or leave unconnected the amplifier
supplies VCCBIAS2, VCCAMP, VCCBIAS1, and also
the inputs for setting the amplifier bias currents RSET1,
RSET2. This reduces the supply current by approxi-
mately 132mA under typical conditions.
The MAX2058 loopback mixer uses a double-balanced
active architecture designed to operate with a 700MHz
to 1200MHz RF frequency range, and a 40MHz to
100MHz LO frequency range. The RF port of the mixer is
connected internally (with an on-chip switch) to the input
of the first attenuator stage. The mixer’s IF port is
matched for a single-ended 50Ω impedance, while the
LO port requires a differential input impedance of 100Ω.
The loopback mixer facilitates a self-diagnostic mode
for cellular transceivers, whereby the Tx band signal at
the input of the mixer can be translated up or down to
the corresponding Rx band. This translated signal can
then be fed back to the radio’s receiver for complete
Tx/Rx loop diagnostics. The loopback mixer is enabled
and disabled with LB_EN. Set LB_EN to a logic-low 0 to
enable the mixer, set LB_EN to a logic-high 1 to disable
the mixer.
The two 5-bit attenuators are programmed with the 3-
wire SPI/MICROWIRE-compatible serial interface using
10-bit words. Bit 9 of the 10-bit data is shifted in first,
along with all remaining data bits, on the rising edge of
the clock regardless of CS being high or low. Once all
the data bits are shifted in, all will be sent to the attenua-
tors on the rising edge of CS, thus changing the attenua-
tion state. For standard SPI operation, pull CS low for the
duration of a valid 10-bit data set (t
tive pulse width includes the setup time of the rising
clock edge to CS transitioning high (t
SPI Interface and Attenuator Settings
Applications Information
Loopback Mixer
EWN
Driver Amplifier
ES
). See Figure 1.
). This CS nega-