BLK_DelayElement2C : A variable delay element with dual control inputs and linear V-to-D characteristics
A variable delay element propagates an input clock in
to an output clock out
with a variable amount of delay.
In this particular model, the delay is controlled by two control voltages vctrl1
and vctrl2
via linear V-to-D characteristics. That is:
delay = delay0 + Kd1*(vctrl1-vctrl1_0) + Kd2*(vctrl2-vctrl2_0)
where the parameter delay0
is the nominal delay when vctrl1
and vctrl2
are at their nominal values set by the parameters vctrl1_0
and vctrl2_0
, respectively. The parameters Kd1
and Kd2
are the control gains of the variable delay element, defined as the rate of change in the delay with respect to the change in vctrl1
and vctrl2
, respectively. In addition, the delay may have the maximum and minimum limits, which are set by the parameters delay_max
and delay_min
, respectively.
This variable delay element model consists of a poly_func
, limit
, and delay_to_clk
primitives, where the poly_func
and limit
primitives calculate a delay value from the vctrl1
and vctrl2
inputs and the delay_to_clk
primitive produces the output clock out
by delaying the input clock in
with the calculated delay amount.
Input/Output Terminals
Name | I/O | Type | Description |
out | output | xbit | output clock |
in | input | xbit | input clock |
vctrl1 | input | xreal | control voltage #1 |
vctrl2 | input | xreal | control voltage #2 |
Parameters
Name | Type | Default | Description |
delay0 | real | 0.8n | delay at nominal vctrl value (s) |
vctrl1_0 | real | 0.5 | nominal value for vctrl1 (V) |
vctrl2_0 | real | 0.5 | nominal value for vctrl2 (V) |
Kd1 | real | -3n | delay control gain for vctrl1 (s/V) |
Kd2 | real | -1.5n | delay control gain for vctrl2 (s/V) |
delay_max | real | 1.4n | maximum limit on delay (s) |
delay_min | real | 0.2n | minimum limit on delay (s) |
List of Testbenches
tb_check : A testbench for checking the basic operation of a variable delay element |
tb_meas_tfdc : A testbench for measuring the voltage-to-delay (V-to-D) characteristics of a variable delay element |
tb_check : A testbench for checking the basic operation of a variable delay element
This testbench checks the basic functionality of a variable delay element by feeding a constant-frequency clock and varying its control voltages. The measured input-to-output delay of the variable delay element is expected to change according to its V-to-D characteristics.
Simulation Results
Figure. input and output waveforms.
tb_meas_tfdc : A testbench for measuring the voltage-to-delay (V-to-D) characteristics of a variable delay element
This testbench measures the voltage-to-delay (V-to-D) characteristics of a variable delay element, by gradually varying the control voltage vctrl1
and measuring the delay. The resulting DC transfer characteristics correspond to the V-to-D characteristics of interest.
Simulation Results
Figure. the voltage-to-delay characteristics.