MAX2850ITK+ Maxim Integrated Products, MAX2850ITK+ Datasheet - Page 21

• Manufacturer Part Number: MAX2850ITK+
• Description: RF Transmitter 5GHz, 4-Ch MIMO Tran smitter WLAN 802.11a
• Manufacturer: Maxim Integrated Products

Specifications of MAX2850ITK+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

In clockout mode, only the crystal oscillator signal is
active at the CLKOUT pin. The rest of the transceiver is
powered down.
In standby mode, PLL, VCO, and LO generation are on.
Tx or Rx modes can be quickly enabled from this mode.
Other blocks may be selectively enabled in this mode.
In receive mode, all Rx circuit blocks are powered on
and active. Antenna signal is applied; RF is downcon-
verted, filtered, and buffered at Rx baseband I and Q
outputs.
In transmit mode, all Tx circuit blocks are powered on
and active. The external PA can be powered on through
the PA_BIAS pins after a programmable delay.
In transmit calibration mode, all Tx circuit blocks are
powered on and active. The AM detector and receiver
I/Q channel buffers are also on. Output signals are
routed to Rx baseband I and Q outputs.
The AM detector multiplies the Tx RF output signal with
itself. The self-mixing product of the wanted sideband
becomes DC voltage and is filtered on-chip. The mix-
ing product between wanted sideband and the carrier
leakage forms Ftone at Rx baseband output. The mixing
product between the wanted sideband and the unwant-
ed sideband forms 2Ftone at Rx baseband output.
As Tx RF output is self-mixed at the AM detector, the
AM detector output responds differently to different gain
settings and power levels. When Tx RF output power
changes by 1dB through Tx gain control, the AM detector
output changes by 2dB as both the wanted sideband and
carrier leakage (or unwanted sideband) change by 1dB.
When Tx RF output carrier leakage (or unwanted side-
band) changes by 1dB while the wanted sideband output
power is constant, the AM detector output changes by
1dB only.
In RF loopback mode, part of the Rx and Tx circuit
blocks except the LNA are powered on and active. The
transmitter 4 I/Q input signal is upconverted to RF, and
the output of the transmitter is fed to the receiver down-
converter input. Output signals are delivered to receiver
MICROWIRE is a trademark of National Semiconductor Corp.
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5GHz, 4-Channel MIMO Transmitter
Transmit Calibration
Transmit (Tx) Mode
Receive (Rx) Mode
Clockout Mode
Standby Mode
RF Loopback
4 baseband I/Q outputs. The I/Q lowpass filters in the
transmitter signal path are bypassed.
In baseband loopback mode, part of the Rx and Tx
baseband circuit blocks are powered and active. The
transmitter 4 I/Q input signal is routed to receiver low-
pass filter input. Output signals are delivered to receiver
4 baseband I/Q outputs.
Set the ENABLE pin to V
oscillator. Program all SPI addresses according to rec-
ommended values. Set SPI Main address 0 D4:D2 from
000 to 001 to engage standby mode. To lock the LO
frequency, the user can set SPI in order of Main address
15, Main address 16, and then Main address 17 to trig-
ger VCO sub-band autoacquisition; the acquisition will
take 2ms. After the LO frequency is locked, set SPI Main
address 0 D4:D2 = 010 and 011 for Rx and Tx operat-
ing modes, respectively. Before engaging Rx mode, set
Main address 5 D1 = 1 to allow fast DC offset settling.
After engaging Rx mode and Rx baseband DC offset
settles, the user can set Main address 5 D1 = 0 to com-
plete Rx DC offset cancellation.
The MAX2850 includes 60 programmable 16-bit reg-
isters. The most significant bit (MSB) is the read/write
selection bit (R/W in Figure 1). The next 5 bits are register
address (A4:A0 in Figure 1). The 10 least significant bits
(LSBs) are register data (D9:D0 in Figure 1). Register
data is loaded through the 4-wire SPI/MICROWIRE™-
compatible serial interface. MSB of data at the DIN pin
is shifted in first and is framed by CS. When CS is low,
the clock is active, and input data is shifted at the rising
edge of the clock at SCLK pin. At the CS rising edge,
the 10-bit data bits are latched into the register selected
by address bits. See Figure 1. To support more than a
32-register address using a 5-bit wide address word,
the bit 0 of address 0 is used to select whether the 5-bit
address word is applied to the main address or local
address. The register values are preserved in shutdown
mode as long as the power-supply voltage is maintained.
There is no power-on SPI register self-reset functionality
in the MAX2850, so the user must program all register
values after power-up. During the read mode, register
data selected by address bits is shifted out to the DOUT
pin at the falling edges of the clock.
Programmable Registers and
CC
for 2ms to start the crystal
4-Wire SPI Interface
Baseband Loopback
Power-On Sequence
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