AC Simulation and Noise Contributionsrmh072000/Site/Software_and_Links_files/4A_slides.pdf• Filter...

1 ADS 2009 (version 1.0) Copyright Agilent Technologies 2009

AC Simulation and Noise Contributions


AC Simulation


AC Simulation Controller


AC Noise calculations

Sort by name or by value: in the dataset.

Blank gives you all contributors.

Nodes for noise are Wire/Pin Labels.


AC sources are for AC simulations

•  I current sources can be used for other simulations to inject current. •  Arrow in symbol shows the direction of current flow.

•  V_AC, P_AC, and I_AC are component names.

•  SRC3, PORT1, and SRC4 are instance names which you can change.

•  Vac = polar (1,0)V is the default value. The polar function can be removed (next slide).

•  Freq = freq is a global variable - you set the start & stop values in the simulation controller. •  P sources are also ports (ok for S-parameter) •  Num=1 is the port number.


Setting AC source values

NOISE and Vdc: By default, noise is turned on for the P_AC source. Use Display tab/settings to make visible. Vdc 10 mV is an offset (superposition).

Equations can also be used: P=1W, P=1+j*1W, P=complex(1,0), etc.

POWER: The dbmtow function converts power in dbm to power in watts for the simulator.

PHASE: The polar function specifies phase. By default, all sources are cosine waves. Use -90 for a sinewave.


Summary of ADS equation types

•  Eqn: post-simulation - Use for calculations in the data display. Use node voltages, functions, and any dataset data.

•  VAR: pre-simulation Use for initializing sweep variables or other settings. VARs are available in the dataset if you select them in the Output tab of the simulation controller.

•  MeasEqn: pre-simulation Use on schematic pre-simulation and it is available in the dataset after simulation. It uses node labels and functions.

schematic

data display


Click here for DDS equations:

Review of Data Display equation editor Insert button gives full path (dataset..) if not the default.

Invalid equations are red:

Click Functions Help = on-line manuals: Functions (measurement expressions) are defined with examples…

Schematic MeasEqns appear in the dataset.

Valid equations are black:


Printing ADS schematics and data

Print… shows printer name, type (most HP Desk Jets & Laser Jets). Use Properties for colors, size, orientation, etc. Export JPG, BMP, GIF to Windows tools.


Stopping an ADS processes

UNIX users kill processes - PC users end processes

PC task manager - NT: ctrl-alt-delete

In a UNIX window, use: ps -ef | tail and you can kill (xxx) a processes.

hpeesofde.exe - closes the ADS program (same as exit) hpeesofsim.exe - stops the simulation or in schematic: hpeesofdds.exe – ends the data display server

If your computer is locked up or if there is any other problem (Data Display), you can safely stop some processes:


Useful Data Display features... •  Copy/Paste: Ctrl C copies / Ctrl V pastes

HOT KEY and DDS command to your keyboard for efficiency and speed - similar to schematic Hot Keys!

•  ALSO for the Data Display: - Hot Keys & Predefined Equations

Document your plots!


Lab 4:

AC Simulations and Noise Contributions


Steps in the Design Process •  Design the RF sys behavioral model receiver •  Test conversion gain, spectrum, etc. •  Start amp_1900 design – subckt parasitics •  Simulate amp DC conditions & bias network •  Simulate amp AC response - verify gain •  Test amp noise contributions •  Simulate amp S-parameter response •  Create a matching topology •  Optimize the amp in & out matching networks •  Filter design – lumped 200MHz LPF •  Filter design – microstrip 1900 MHz BPF •  Transient and Momentum filter analysis •  Amp spectrum, delivered power, Zin - HB •  Test amp comp, distortion, two-tone, TOI •  CE basics for spectrum and baseband •  CE for amp_1900 with GSM source •  Replace amp and filters in rf_sys receiver •  Test conversion gain, NF, swept LO power •  Final CDMA system test CE with fancy DDS •  Co-simulation of behavioral system

You are here:


Simulation setup with Noise

NOTE: By default, the AC controller sweeps the global variable freq using the settings shown and ignores any setting in the source.

Noise is turned on and the noise node defined.


Set up a Meas Eqn and Outputs... Generic Meas Eqn from any simulation palette:

Use the Controller Output tab (works the same in all controllers) to specify which simulation data is output to the dataset. Here, Vcc Is eliminated from the dataset.

NOTE: You can attach specific equations to specific simulation controllers, using the Display tab and checking the box for:


Operate on data: equations & functions Write an equation using the editor.

Operate directly on listed or plotted data by typing in a function (dB):

Edit and change to another plot type:

List the Meas Eqn & DDS equation:


Plot phase and calculated group delay

Calculate group delay with an equation using Phase data. Also, control marker readout formats:

Plot the phase of Vin and Vout:


Variables and the what function…what? •  Insert a list of Vout •  Click on: Trace Options •  Then click: Variable Info…

Or, use the what function on any data and get the same information - this will be useful later when the data becomes more dependent:

Next, sweeping parameters…

The value of a dataset item, such as a node voltage, depends on its variables: Vout here is dependent on the ADS freq variable.


Parameter Sweep: bias voltage AC simulation with a parameter sweep component to sweep a VAR: Vbias.

Explicit dataset path uses ..

Type in the freq for the marker!

Understanding the data…


Understanding Lab Results: data

Sweep DC bias and AC frequency: Vout is a function of V_bias and freq: Vout [V_bias,freq]

•  Vout returns all data, for all index values 0 through N of each sweep

•  Vout[0,1] returns V_bias only at index 0, and freq only at index 1

•  Vout[::,1] returns all values of V_bias, and freq at index 1

•  Vout[0,::] returns V_bias at index 0, and all values of freq

•  Vout[0::2::6,::] returns V_bias at index values 0, 2, 4, 6 and all values of freq

SYNTAX NOTE: Double colon :: is equivalent to “all values” like a wildcard. For example[a::b::c] a=start, b=increment, c=stop. More information in Data Display manual:Working with Multidimensional Data

Concept: data in dataset is a function of one or more variables, and all data is indexed beginning with index value 0.

Index for freq:

0 1 2 3 4 5 6

Index for V_bias = 0 if 2V is the first value.


Parameter Sweep of voltage For an AC simulation, use a parameter sweep component to sweep a VAR: Vbias.

Explicit dataset path uses ..

Type in the freq for the marker!

Start the lab now!

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