Traveling wave electrode transmission line filter
Keywords
electrical, unidirectional
Ports
| Name | Type |
|---|---|
| input | Electrical Signal |
| output | Electrical Signal |
Properties
General Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
name Defines the name of the element. |
Traveling Wave Electrode | - | - |
|
annotate Defines whether or not to display annotations on the schematic editor. |
true | - | [true, false] |
|
enabled Defines whether or not the element is enabled. |
true | - | [true, false] |
|
type Defines the element unique type (read only). |
Traveling Wave Electrode | - | - |
|
description A brief description of the elements functionality. |
Traveling wave electrode transmission line filter | - | - |
|
prefix Defines the element name prefix. |
TW | - | - |
|
model Defines the element model name. |
- | - | - |
|
library Defines the element location or source in the library (custom or design kit). |
- | - | - |
|
local path Defines the local path or working folder $LOCAL for the element. |
- | - | - |
|
url An optional URL address pointing to the element online help. |
- | - | - |
Standard Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
length The interaction length of the modulator. |
0.01 | m | [0, +∞) |
|
loss type Defines if the loss is constant or frequency dependent. Frequency dependency can be linear (~1/f), square root [~1/sqrt(f)] or from a table. |
constant | - | [constant, linear, square root, table |
|
microwave loss Defines the microwave loss. |
0 | dB/m | [0, +∞) |
|
loss reference frequency Central frequency of operation. |
1 | Hz | [0, +∞) |
|
load loss from file Defines whether or not to load frequency dependent attenuation values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
loss filename The file containing the frequency dependent attenuation values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
loss table The table containing the frequency dependent attenuation values |
<2> [1, 0] | - | - |
Standard/Source Impedance Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
source impedance type Defines if the impedance is constant or frequency dependent. |
constant | - | [constant, table |
|
source resistance Defines the source resistance. |
50 | Ohms | [0, +∞) |
|
source reactance Defines the source reactance. |
0 | Ohms | (-∞, +∞) |
|
load source impedance from file Defines whether or not to load impedance values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
source impedance filename The file containing frequency dependent impedance values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
source impedance table The table containing the frequency dependent impedance values. |
<3> [1, 50, 0] | - | - |
Standard/Characteristic Impedance Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
characteristic impedance type Defines if the impedance is constant or frequency dependent. |
constant | - | [constant, table |
|
characteristic resistance Defines the characteristic resistance. |
50 | Ohms | [0, +∞) |
|
characteristic reactance Defines the characteristic reactance. |
0 | Ohms | (-∞, +∞) |
|
load characteristic impedance from file Defines whether or not to load impedance values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
characteristic impedance filename The file containing frequency dependent impedance values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
characteristic impedance table The table containing the frequency dependent impedance values. |
<3> [1, 50, 0] | - | - |
Standard/Terminating Impedance Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
terminating impedance type Defines if the impedance is constant or frequency dependent. |
constant | - | [constant, table |
|
terminating resistance Defines the terminating resistance. |
50 | Ohms | [0, +∞) |
|
terminating reactance Defines the terminating reactance. |
0 | Ohms | (-∞, +∞) |
|
load terminating impedance from file Defines whether or not to load impedance values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
terminating impedance filename The file containing frequency dependent impedance values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
terminating impedance table The table containing the frequency dependent impedance values. |
<3> [1, 50, 0] | - | - |
Standard/Junction Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
junction resistance Defines the junction resistance. |
0 | ohm.m | [0, +∞) |
|
junction capacitance type Defines if the junction capacitance is constant or voltage dependent. |
constant | - | [constant, table |
|
constant junction capacitance Defines the junction capacitance. |
0 | F/m | [0, +∞) |
|
load junction capacitance from file Defines whether or not to load measurements from an input file or to use the currently stored values. |
false | - | [true, false] |
|
junction capacitance filename The file containing the measurement data. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
junction capacitance table A matrix editor for users to read the element current data values. |
<30,2> [-3, -2.896551724, -2.793103448,...] | - | - |
Waveguide Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
microwave index type Defines if the microwave index is constant or frequency dependent. |
constant | - | [constant, table |
|
microwave index Defines the the microwave group index. |
4 | - | [0, +∞) |
|
load microwave index from file Defines whether or not to load microwave index values from an input file or to use the currently stored values. |
false | - | [true, false] |
|
microwave index filename The file containing frequency dependent microwave index values. Refer to the Implementation Details section for the format expected. |
- | - | - |
|
microwave index table The table containing the frequency dependent microwave index values. |
<2> [1, 4] | - | - |
|
optical index Defines the waveguide group index. |
3 | - | [0, +∞) |
Numerical Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
transfer function Defines if the modulator response uses the frequency dependent modulation reduction factor or the frequency dependent average voltage as the transfer function. |
modulation reduction factor | - | [modulation reduction factor, modulation voltage |
Numerical/Digital Filter Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
time variant digital filter Defines the operation of the internal time varying digital filter. |
interpolate | - | [interpolate, update |
|
single tap filter Defines whether or not to use a single tap digital filter to represent the element transfer function in time domain. |
false | - | [true, false] |
|
number of taps estimation Defines the method used to estimate the number of taps of the digital filter. |
fit tolerance | - | [disabled, fit tolerance, group delay |
|
filter fit tolerance Defines the mean square error for the fitting function. |
0.001 | - | (0, 1) |
|
window function Defines the window type for the digital filter. |
rectangular | - | [rectangular, hamming, hanning |
|
number of fir taps Defines the number of coefficients for digital filter. |
256 | - | [1, +∞) |
|
maximum number of fir taps Defines the number of coefficients for digital filter. |
4096 | - | [1, +∞) |
|
filter delay Defines the time delay equivalent to a number of coefficients for digital filter. |
0 | s | [0, +∞) |
|
initialize filter taps Defines whether to use the initial input signal to initialize filter state values or to set them to zero values. |
false | - | [true, false] |
Diagnostic Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
run diagnostic Enables the frequency response of the designed filter implementation and the ideal frequency response to be generated as results. |
false | - | [true, false] |
|
diagnostic size The number of frequency points used when calculating the filter frequency response. |
1024 | - | [2, +∞) |
|
stop frequency The upper frequency limit for the calculated graph. |
50e+009 | Hz | (0, +∞) |
Results
| Name | Description |
|---|---|
| diagnostic/normalized average voltage | The normalized average voltage vs. frequency. |
| diagnostic/response #/transmission | The complex transmission vs. frequency corresponding to the ideal and designed filter. |
| diagnostic/response #/gain | The gain vs. frequency corresponding to the ideal and designed filter. |
| diagnostic/response #/error | Mean square error comparing the frequency response of the designed filter implementation with the ideal frequency response. |
====================================
Implementation Details
Since the 2017b R3 release, the Traveling Wave Electrode element implements two options for the transfer function, namely the "modulation reduction factor" and the "modulation voltage". The "modulation reduction factor" is defined as:
|
$$ r(\omega)=\left|\frac{V_{avg}(\omega)}{V_{avg}(0)}\right| $$ |
(1) |
and with the source impedance impact normalized away, the electrode output voltage with this option ("modulation reduction factor") is independent of source voltage, because the voltage is normalized to itself at ω=0.
The absolute response output is given by the option "modulation voltage", which is simply represented by Vavg(ω). With this transfer function option, the electrode output is impacted by the source impedance and overall, the larger the impedance mismatch between the device and source, the smaller the voltage on the device, and the smaller the phase-shift.
For more implementation details of Traveling Wave Electrode, please see the application example Traveling Wave Modulators for more information.
Related Publications
- Hao Xu et al., "Demonstration and Characterization of High-Speed Silicon Depletion-Mode Mach–Zehnder Modulators", IEEE Journal of Selected Topics in Quantum Electronics, Vol. 20, No. 4 (2014)