Single Measurement ================== Main Menu ~~~~~~~~~ Assuming all devices are connected, a two-port system is modeled as follows: .. figure:: ../_images/PNG/setup_type_ltf.png :width: 50 % :align: center A 2-Port System with Unknown DUT. The Main Menu summarizes the test-bench as shown below: .. figure:: ../_images/PNG/main_menu_view.png :width: 100 % :align: center The 2-port System Dashboard Representation The Main Menu consists of two-primary elements: 1. The Sidebar 2. The Instrument Manager Sidebar ------- The Sidebar is a multi-tab window that can be customized based on the desired application. The Main Menu defaults to the Main tab. .. figure:: ../_images/PNG/main_tab.png :width: 100 % :align: center Start by configuring the *global* System Settings in the sidebar by specifying: * Frequency Sweep * :code:`Settings().f_0`: The fundamental carrier frequency. * :code:`Settings().num_harmonics`: The number of harmonics frequencies. * Time Sweep * :code:`Settings().t_{stop}`: the measurement period. * :code:`Settings().t_{step}`: the measurement time-step. * Trigger * :code:`Settings().trigger_device`: the trigger output device type. * :code:`Settings().trigger_port`: the trigger output device port. * Datagroup * :code:`Settings().datagroup`: The name of the database file (default **Single.h5**). * :code:`Settings().trigger_port`: The name of a node in a database file (default **Default**). You can specify additional global variables: * In the :code:`sknrf.yml` config file before runtime. * In the Settings Menu during runtime. Instrument Manager ------------------ The Instrument Manager consists of: * :code:`Settings().num_ports + 1` ports * Port 0 is a reserved calibration reference port. * :code:`Settings().num_duts` DUTs * The aux devices consisting of non-compatible instruments: * Power Meter * Spectrum Analyzer * Vector Network Analyzer Ports ----- The number of ports is configured in :code:`sknrf.yml` and is available at runtime in :code:`Settings().num_ports`. Each measurement port is represented by a column in the Instrument Manager. .. figure:: ../_images/PNG/instrument_manager_port.png :width: 100 % :align: center A **Port** :py:class:`PortModel ` a collection of devices that can be connected to a measurement port: 1. :code:`port.lfsource`, a low-frequency signal source that *sets* :math:`v(t, f)`. 2. :code:`port.lfreceiver`, a low-frequency signal receiver that *gets* :math:`v(t, f)` and :math:`i(t, f)`. 3. :code:`port.lfztuner`, a low-frequency impedance controller that *sets* and *gets* :math:`z_p(t, f)` 4. :code:`port.rfsource`, a high-frequency signal source that *sets* :math:`a_p(t, f)`. 5. :code:`port.rfreceiver`, a high-frequency signal receiver that *gets* :math:`a_p(t, f)` and :math:`b_p(t, f)`. 6. :code:`port.rfztuner`, a high-frequency impedance controller that *sets* and *gets* :math:`\gamma_p(t, f)`. Each measurement port provides a Thevenin Equivalent at Low-Frequency (LF) and High-Frequency (HF). Thus the following equations fully describe the inputs and outputs of a port: **VIZ->BAG** .. figure:: ../_images/PNG/NVNA_meas_AB.png :width: 100 % :align: center .. math:: :nowrap: \begin{eqnarray} B_p & = & \frac{1}{2 \sqrt{ \Re Z_p }} \left( V - Z_p^*I \right) \\ A_p & = & \frac{1}{2 \sqrt{ \Re Z_p }} \left( V + Z_pI \right) \\ \Gamma_p & = & \frac{Z_p - Z_0}{Z_p + Z_0} \\ \end{eqnarray} **BAG->VIZ** .. figure:: ../_images/PNG/NVNA_meas_VI.png :width: 100 % :align: center .. math:: :nowrap: \begin{eqnarray} V & = & \frac{1}{\sqrt{ \Re Z_p }} * \left( Z_p^*a + Z_pb \right) \\ I & = & \frac{1}{\sqrt{ \Re Z_p }} * \left( a - b \right) \\ Z_p & = & z0 \frac{1 + \Gamma_p}{-\Gamma_p + 1} \\ \end{eqnarray} where, .. math:: :nowrap: \begin{eqnarray} V & = & \mathcal{F} \left( v(t, f) \right) \text{w.r.t } t\\ I & = & \mathcal{F} \left( i(t, f) \right) \text{w.r.t } t\\ Z_p & = & \mathcal{F} \left( z_p(t, f) \right) \text{w.r.t } t\\ B_p & = & \mathcal{F} \left( v(t, f) \right) \text{w.r.t } t\\ A_p & = & \mathcal{F} \left( i(t, f) \right) \text{w.r.t } t\\ \Gamma_p & = & \mathcal{F} \left( \gamma_p(t, f) \right) \text{w.r.t } t\\ \end{eqnarray} These raw waveforms have the following meaning: * :math:`v(t, f)`: The input voltage (default :math:`0.0`). * :math:`i(t, f)`: The output current (default :math:`0.0`). * :math:`z(t, f)`: The port termination impedance (default :math:`z_0 = 50.0`) * :math:`b_p(t, f)`: The output (reflected) power-wave (default :math:`0.0`). * :math:`a_p(t, f)`: The input (incident) power-wave (default :math:`0.0`). * :math:`\gamma_p(t, f)`: The port reflection coefficient (default :math:`0.0`). Since each of these waveforms has a *default value*, we need only connect an instrument when we know that the DUT does not meet these assumptions: * Devices with direct access to power and ground do not require a :code:`port.lfztuner`. * Devices matched to 50 Ohm do not require a :code:`port.rfztuner`. * Devices matched to 50 Ohm do not require a :code:`port.rfreceiver` that can measure :math:`a_p(t, f)`. * LF circuits do not require :code:`port.rfsource`, :code:`port.rfreceiver`, :code:`port.rfztuner`. * RF circuits do not require :code:`port.lfsource`, :code:`port.lfreceiver`, :code:`port.lfztuner`. Supported Instruments ~~~~~~~~~~~~~~~~~~~~~ .. raw:: html

LF Source LF Source

DC Supply

AWG

DAC

 

 

LF Receiver LF Receiver

Multimeter

Oscilloscope

ADC

 

 

LF ZTuner LF ZTuner

Open/Short Circuit

Varactor

Active Load

 

 

RF Source RF Source

Signal Generator

VSG

AWG

Pulse Generator

SRD

RF Receiver RF Receiver

VNA

VSA

Power-Meter

Oscilloscope

Sampling Scope

LF ZTuner RF ZTuner

50 Ohms

Passive Load

Active Load

 

 

The choice of :code:`port.rfreceiver` determines the trade-off between: * speed vs. accuracy * digital vs. analog * affordable vs. expensive This architecture manage the trade-off between digital and analog verification: * **Oscilloscope**: Low-Cost, digitally sampled receiver in an embedded-device. * **(Sub)-Sampling Oscilloscope**: Mixed-Signal with a slow digital sample-rate and fast analog sample-rate. * **Network Analyzer**: High-Cost, high accuracy measurement for analog circuits in an R&D lab. Auxiliary Port ~~~~~~~~~~~~~~ The following instruments (found in most labs) provide turn-key design verification, but result in significant challenges due to low inter-operability. These instruments (and suggested alternatives) are: * **Power Meter (Anything Else)** * Calibrated to NIST standards, but are limited to scalar measurements. * Requires manual range adjustment to achieve accuracy * **Spectrum Analyzer (Signal Analyzer)**: * Scalar frequency swept measurements do not translate to the envelope domain. * A Signal Analyzer is a good alternative. * **3-Receiver VNA (4-Receiver VNA)**: * 3-Receiver VNAs use 12-Term error correction to extract S-Parameter models. * 4-Receiver VNAs use 8-Term (or 12-term error correction) to measrure reflectometry (o extract S-Parameter models). Since these instruments are still common, the **Aux Port** provides a way to log these measurements: