UG-1828
Preliminary Technical Data
Rev. PrC | Page 72 of 338
Figure 62: Visualization of Timing Parameters
Broadly speaking, the delays present in the system can be described as follows:
•
Enable Setup Delay
is the time taken for ADRV9001 to power up its analog front end. This may or may not include PLL tuning
time based on the use case, for example, when Tx and Rx share the same IO but at different frequency, PLL tuning is needed at
the frame boundary.
•
Propagation Delay
is the delay of data from antenna to RF interface in either direction. Given that this delay encompasses
external components it is impossible to determine a priori what this delay should be, it simply must be measured. Naturally, this
delay is also very setup dependent and board layout dependent. It does not need to be provided to ADRV9001, but it can be
used to derive other parameters required by the ADRV9001.
•
Enable Rise-to-On Delay
is the delay between TX_ENABLE rising edge and Rx/Tx switch switching to the Tx channel.
Conversely, it is also the delay between RX_ENABLE rising edge and the external Rx LNA powering up. It should align with the
desired time when the first symbol is on air. Typically, this delay is equal in length to the propagation delay, however if the setup
uses Guard Data to envelop the Frame on Air this extra Guard time must also be accounted for. This delay will not apply to
every setup, however. Some applications give control of the antenna switch to the user, for example hand-held radio applications
often allow users to control whether to Transmit or Receive data on a single antenna. If ADRV9001 is not controlling antenna
switch, this parameter is not needed except to determine other parameters.
•
Enable Rise-to-Analog-On Delay
is the delay between TX_ENABLE / RX_ENABLE rising edge and analog power up
beginning. This is a user defined parameter, the purpose of which is to align the analog power up with the Frame on Air. Note
that this parameter is used to aid in saving power in setups where the propagation delay is quite long. If Tx propagation delay is
long, the analog power up can be delayed for power saving or to keep Tx AFE powered down during Rx frame, and vice versa. If
the propagation delay is small, this should be set to 0. If this parameter is greater than its max bound, the antenna switch / LNA
power on time could be delayed.
•
Enable Guard Delay
is the guard time at the beginning of the RF frame. This part of the Frame on Air does not contain useful
data, instead it is used as a barrier between the end of device setup and start of data transmission. Any distortions or noise
applied to the guard data by the transmitter device will not affect error rates at the receiver. Not every application uses guard
data, however for those that do it is worth noting that the Guard Delay only accounts for the Guard data at the
beginning
of the
frame, not the end. The Guard data at the end of the frame is accounted for with the Hold delay. Guard Delay is reserved for
future use, should be set to 0 currently.
•
Enable Hold Delay
is the delay between RX_ENABLE falling edge and masking off datapath data sent over interface. Similarly,
it is also the delay between the falling edge of TX_ENABLE and the Tx interface being disabled.
•
Enable Fall-to-Off Delay
is the delay between RX_ENABLE falling edge and the powering down the external Rx LNA. If
ADRV9001 not controlling external Rx LNA power, this parameter can still be used to delay analog power down. ADRV9001
