BLK_DelayElement : A variable delay element with a linear V-to-D characteristic

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 a control voltage vctrl via a linear V-to-D characteristic. That is:

    delay = delay0 + Kd*(vctrl-vctrl0)

where the parameter delay0 is the nominal delay when vctrl is at its nominal value (the parameter vctrl0) and the parameter Kd is the control gain of the variable delay element, defined as the rate of change in the delay with respect to the vctrl change. In addition, the delay element 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 vctrl input 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
vctrl	input	xreal	control voltage

Parameters

Name	Type	Default	Description
vctrl0	real	0.5	nominal vctrl value (V)
delay0	real	0.8n	delay at nominal vctrl value (s)
Kd	real	-3n	delay control gain (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 voltage. The measured input-to-output delay of the variable delay element is expected to change according to its V-to-D characteristics.

Simulation Results

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 vctrl and measuring the delay. The resulting DC transfer characteristics correspond to the V-to-D characteristics of interest.

Simulation Results