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| author | Tom Tsou <tom.tsou@ettus.com> | 2015-06-17 15:38:50 -0700 |
|---|---|---|
| committer | Martin Braun <martin.braun@ettus.com> | 2015-07-13 14:59:16 -0700 |
| commit | 2b837f2ff7e9836dc4114791308bf2c9a37b807c (patch) | |
| tree | db73864ff543d7825251dbd7a3ba58122c596a06 /CHANGELOG | |
| parent | f9c8dfbd8db24b64f305f04a2d1b83b84c16aa5f (diff) | |
| download | uhd-2b837f2ff7e9836dc4114791308bf2c9a37b807c.tar.gz uhd-2b837f2ff7e9836dc4114791308bf2c9a37b807c.tar.bz2 uhd-2b837f2ff7e9836dc4114791308bf2c9a37b807c.zip | |
ad9361: Invert phase on Rx LNA bypass path
This patch resolves issue #823
"B200: Receive RF DC calibration makes calibration worse below 34 dB"
According to ADI reference documents, enabling any of the 3 LNA's in the
receive path causes a 180 degree phase shift. Correspondingly, we invert
the LNA bypass path (gain indices below 34 dB) to match. Testing,
however, reveals that one of these statements or the polarity inversion
setting itself is false. Disabling the switch results in expected
behavior and proper phase alignment.
Overall effect is up to 60 dB of DC offset suppression ahead of the Rx
analog LPF. This reduces the problematic dependency on active baseband
tracking and may resolves multiple tracking stability issues.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Diffstat (limited to 'CHANGELOG')
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