evm629axf Semtech Corporation, evm629axf Datasheet - Page 5

• Manufacturer Part Number: evm629axf
• Description: Timing Deskew Quad Fanout Element
• Manufacturer: Semtech Corporation

Fine Delay
Fine delay is accomplished using an analog delay cell and
an on-chip 6 bit DAC (see Figure 2). The fine delay range
is designed to be ~2X the coarse delay resolution.
Fine delay provides a total delay span of:
Note: Because the transfer function is non-linear, some
LSB steps could be as large as 5 ps.
Each channel has its own unique delay setting and may
be programmed independently from all other channels.
The fine delay of any channel will not affect the coarse
delay of that channel, nor will it affect the overall delay of
any other channel.
The propagation delay of a rising and falling edge will track
each other over the entire span of fine delay. (Adding or
subtracting fine delay will not cause pulse width distor-
tion.)
TEST AND MEASUREMENT PRODUCTS
Circuit Description (continued)
2005 Semtech Corp. Rev. 3, 8/1/05
LSB 1 Fine LSB
MSP 32 Fine LSB =
0 ns
2 Fine LSB
4 Fine LSB
8 Fine LSB
16 Fine LSB
Fine Delay Range
=
=
=
=
=
2.5 ps (see note)
5 ps
10 ps
20 ps
40 ps
80 ps
Figure 2. Fine Delay Architecture
157.5 ps.
6 Bit DAC
T
5
Fine Delay Select
The fine delay section may be selected or bypassed by a
multiplexer (see Figure 2). If SFD (Select Fine Delay) is
high, Fine Delay will be used. If SFD is low, Fine Delay will
be bypassed.
Fine Delay DAC Outputs
DAC_FINE_(0–3) are analog voltage outputs from the on-
board DACs which program the fine delay elements of
each channel.
DAC_FINE_(0-3) pins are for test purposes only. Nothing
should be connected to these pins.
SFD
D
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1
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