LMS6002D Quick Starter Manual for Evaluation Board
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P a g e
© Copyright Lime Microsystems
Rev: 2.2
Last modified: 03/05/2012
Bypass configurations
The various bypass test modes and loop back test modes can be implemented by selecting
from the drop down boxes, default is Normal operation.
Automatic Calibration
The Automatic calibration buttons can be used to run through the series of SPI commands
required to implement the various self-calibration routines provided on the chip. Use of these
macros is implemented as part of a calibration procedure and each button does not carry out a
full calibration, use of the buttons in the wrong context could make the calibration state
worse rather than better.
Automatic calibration should be done in the following order:
a.
LPF Core – Press LPF core button
Executes the process related resistor capacitor (RC) calibration. LPF Core calibration is
performed once per device to ensure that the corner frequencies of the LPFs are optimized.
The calibration selects the LPF response which is closest and above the required bandwidth.
This ensures modulation quality is not adversely impacted but sufficient rejection is provided
for adjacent and alternate channel attenuation.
This should be done 1
st
as optimum DC calibration values for LPF’s will change if this is
done after the filter DC calibration.
b.
Transmitter
The transmitter calibration executes a DC calibration on the TX LPF (I and Q) circuit. This
makes the DC contribution at output of filters zero so that DC level at the mixer input does
not change when the TX VGA1 gain is changed.
When executing this calibration make sure that no signal is applied to the transmit path. For
better DC calibration low DC level signal can applied from baseband via DAC’s to transmit
path.
c.
Receiver
Executes a DC calibration on the Rx LPF (I and Q), and Rx VGA2 (I and Q). This minimizes
the DC contribution at output of filters and Rx VGA2.
When executing this calibration make sure that there is no signal applied to Rx input.