Help me on analog ciruit simulation- Cadence Virtuso

cadence current source

Hello everyone

Can anyone say that why there is voltage across an IDEAL current source taken from analog library in Cadence Virtuoso placed in the circuit. while simulation.

cadence simulation current source

By definition, An IDEAL current source can have any Voltage drop across it. The voltage drop across the ideal current source will be determined by the other surrounding circuit elements.

cadence+post simulation

Yes, an ideal current source means that it gives out constant/fixed current irrespective of the potential difference across it. Potential difference across the ideal current source does not imply its resistance.

This is my understanding. Correct me if I am wrong.

cinch

Hi,

Current source is nothing but voltage source with very high impedence.

Without voltage no thought for current.

Regards,
senthil

Please visit the following website to download
Cadence Virtuoso Spectre RF Tools (Leccture Manual 423 pages + Lab Book 344 pages)
http://www.eetop.cn/bbs/thread-193576-1-1.html


Table of Contents
Virtuoso Spectre RF Tools
Module 1 Introduction
There are no labs for this module. ..... 1-1
Module 2 PSS and Swept PSS Analysis
Lab 2-1 Getting Started ..... 2-1
Logging In...... 2-1
Starting Cadence Software................. 2-1
Lab 2-2 Running a Voltage Conversion Gain Simulation ...... 2-3
Opening the ne600 Schematic ........... 2-3
Editing the Port Symbols . 2-5
Setting Up the Simulation Environment.............. 2-8
Setting Up the Default Plot Output.. 2-10
Setting Up the PSS Simulation ........ 2-11
Verifying the Fundamental (Beat) Frequency ... 2-12
Running the PSS Simulation............ 2-14
Lab 2-3 Displaying the Voltage Conversion Gain ................ 2-16
Using Direct Plot—Method 1 ......... 2-16
Using Direct Plot—Method 2 ......... 2-19
Lab 2-4 Running a 1 dB Compression Point Simulation ...... 2-23
Setting Up for Swept PSS................ 2-23
Setting the Analysis Options............ 2-24
Plotting the 1 dB Compression Point................. 2-26
Module 3 PAC Analysis
Lab 3-1 Running a PAC Conversion Gain Simulation ........... 3-1
Setting Up the Simulation Environment.............. 3-5
Setting Up the PSS Simulation .......... 3-6
Setting Up the PAC Simulation ......... 3-8
Running the PSS Simulation Followed by PAC 3-10
Plotting the Conversion Gain........... 3-11
Running and Plotting PAC Results with Real Frequency Values ....... 3-14
Lab 3-2 Running a Swept Small-Signal IP3 Simulation ....... 3-18
Modifying the RF Port Parameters for an IP3 Simulation... 3-18
Setting Up the Swept PSS Simulation ............... 3-19
Setting Up the Single Point PAC Simulation .... 3-21
Running a PSS Sweep Simulation Followed by PAC......... 3-23
Plotting the IP3 Curve.... 3-24
Module 4 PXF Analysis
Lab 4-1 RF Conversion Gain Simulation.............. 4-1
Modifying the RF Port Parameters for PXF Analysis ........... 4-1
Setting Up the Simulation Environment.............. 4-4
Setting Up the PXF Simulation ......... 4-4
Running the PSS Simulation Followed by PXF .. 4-9
Plotting the RF to IF Conversion Gain ................ 4-9
Running and Plotting PXF Results with Real Frequency Values........ 4-11
Lab 4-2 Power Supply Rejection....... 4-13
Plotting the Power Supply Rejection ................. 4-13
Module 5 PNoise Analysis
Lab 5-1 Noise Figure and Output Noise Analysis 5-1
Setting Up the Simulation Environment.............. 5-5
Running the PSS Simulation Followed by PNoise................ 5-9
Plotting the Output Noise and Noise Figure........ 5-9
Lab 5-2 Printing the Noise Summary Report ...... 5-13
The Noise Summary Report ............ 5-13
Lab 5-3 Running a PSS/PNoise Analysis on a Tunable Oscillator ..... 5-15
Oscillator Notes ............. 5-15
Opening the Oscillator Schematic ... 5-16
Setting Up the Simulation Environment............ 5-17
Setting Up the PSS and PNoise Simulation....... 5-18
Running PSS and PNoise Simulation ................ 5-23
Plotting the Simulation Results........ 5-23
Table of Contents Virtuoso Spectre RF Tools
Lab 5-4 Calculating Time-Varying Instantaneous Noise Power......... 5-28
Opening the Design ....... 5-28
Setting Up the Simulation Environment............ 5-29
Setting Up the PSS Analysis............ 5-29
Setting Up the PNoise Analysis....... 5-31
Running the PSS Simulation Followed by PNoise.............. 5-34
Plotting Time Domain Noise Results ................ 5-35
Calculating Time-Varying Noise Power............ 5-36
Module 6 Periodic S-Parameter (PSP) Analysis
Lab 6-1 Periodic S-Parameter (PSP) Analysis ...... 6-1
Setting Up the Simulation Environment.............. 6-5
Setting Up the PSS Simulation .......... 6-6
Setting up the PSP Analysis............... 6-8
Running the Simulation . 6-11
Plotting the Noise Figure ................. 6-11
Plotting Different Types of Noise Figure .......... 6-13
Plotting Gain 6-14
Plotting Periodic S-Parameters ........ 6-16
Module 7 QPSS Analysis
Lab 7-1 Running Simulation with QPSS .............. 7-1
Modifying RF Port Parameters for QPSS Analysis............... 7-1
Setting Up the Simulation Environment.............. 7-4
Setting Up the QPSS Simulation ....... 7-5
Selecting Outputs for Current and Power Plots ... 7-7
Changing the RF Input Power ........... 7-8
Running the QPSS Simulation......... 7-10
Plotting Simulation Results Using WaveScan... 7-10
Plotting Power................ 7-16
Lab 7-2 Simulating IP3 QPSS Intermodulation Distortion... 7-19
Modifying the RF Source in the Schematic....... 7-19
Setting Up and Running the QPSS Sweep Simulation ........ 7-21
Running the Swept QPSS Simulation................ 7-23
Displaying the IP3 Plot .. 7-24
Module 8 QPAC Analysis
There are no labs for this module. ..... 8-1

Module 9 QPAC & QPXF Analysis
Lab 9-1 QPSS Analysis with Small Signal QPAC and QPXF Analyses .. 9-1
Opening the mixer2 Schematic.......... 9-1
Setting Up the Simulation Environment.............. 9-3
Editing Design Variables . 9-4
Setting Up the QPSS Simulation ....... 9-5
Setting Up the QPAC Simulation ...... 9-6
Setting Up the QPXF Simulation....... 9-8
Running the Simulation . 9-10
Plotting the Results ........ 9-11
Plotting Isolation Curves ................. 9-14
Lab 9-2 Running QPSS with QPAC and QPXF Analyses.... 9-16
Setting Up the Simulation................ 9-16
Running the Simulation . 9-17
Plotting the Results ........ 9-17
Plotting the QPXF RF to IF Transfer Function vs. Input Frequency .. 9-21
Plotting the LO Leakage at the IF Output.......... 9-22
Module 10 QPNoise Analysis
Lab 10-1 QPSS Analysis with a Small-Signal Noise Analysis QPNoise . 10-1
Editing the Schematic .... 10-1
Setting Up the Simulation Environment............ 10-7
Setting Up the QPSS Simulation ..... 10-8
Setting Up the QPNoise Simulation 10-9
Editing the Design Variable........... 10-11
Saving Simulation Outputs ............ 10-12
Running the Simulation ................. 10-13
Plotting the Voltage and Power ..... 10-13
Plotting Power.............. 10-17
Plotting the Noise Figure ............... 10-18
Table of Contents Virtuoso Spectre RF Tools
Module 11 QPSP Analysis
Lab 11-1 QPSS Analysis with a Small Signal S-Parameter Analysis QPSP 11-1
Editing the Schematic .... 11-1
Setting Up the Simulation Environment............ 11-5
Setting Up the QPSS Simulation ..... 11-6
Setting Up the QPSP Simulation ..... 11-8
Running the QPSS Simulation Followed by QPSP........... 11-11
Plotting the Results ...... 11-12
Module 12 Envelope Following Analysis
Lab 12-1 Envelope Following Analysis and ACPR................ 12-1
Setting Up the Simulation Environment............ 12-2
Setting Up the ENVLP Simulation.. 12-2
Running the Envelope Following Simulation.... 12-4
Viewing the Envelope Following Results ......... 12-4
Lab 12-2 Following the Change in the Information (Baseband Signal) Through the Circuit....... 12-8
Plotting the Complete Baseband Signal........... 12-15
Plotting the Baseband Trajectory... 12-17
Lab 12-3 Plotting the Adjacent Channel Power Ratio .......... 12-20
Module 13 S-Parameter Analysis
Lab 13-1 S-Parameter Analysis and Plotting ........ 13-1
Reviewing the twa3b Schematic...... 13-1
Setting Up the Simulation Environment............ 13-2
Setting the Path to the S-Parameter Data Files .. 13-3
Choosing Analyses ........ 13-3
Simulating The Design .. 13-6
Viewing Simulation Results with Direct Plot.... 13-6
Plotting the Gain of the Circuit........ 13-9
Plotting VSWR and Gain............... 13-10
Plotting S11 and S22 on a Smith Chart ........... 13-12
Lab 13-2 Plotting Stability Circles .... 13-15
Setting Up the Design .. 13-15
Setting Up the Simulation Environment.......... 13-16
Setting the Path to the S-Parameter Data File.. 13-17
Choosing Analyses ...... 13-18
Running the Simulation ................. 13-20
Viewing Simulation Results with Direct Plot.. 13-21
Lab 13-3 Simulating Linear Two-Port Noise...... 13-25
Setting Up the Design .. 13-25
Setting Up the Simulation Environment.......... 13-27
Choosing Analyses ...... 13-27
Running the Simulation ................. 13-29
Viewing Simulation Results with Direct Plot.. 13-30
Lab 13-4 Comparing Measured Data to Simulation Data with a Schematic Model. 13-38
Setting Up the Design .. 13-38
Setting Up the Simulation Environment.......... 13-39
Setting the Path to the S-Parameter Data File.. 13-40
Choosing Analyses ...... 13-40
Simulating with Measured S-Parameter Data.. 13-42
Viewing Simulation Results with Direct Plot.. 13-42
Saving the Simulation Results ....... 13-44
Lab 13-5 Simulating with a Schematic Model.... 13-45
Setting the Schematic Model ......... 13-45
Choosing Analyses ...... 13-48
Simulating the ATF26100opt Component....... 13-49
Using the Direct Plot Tool to Compare Simulation Results................ 13-49
Lab 13-6 Tabulated S-Parameters in the Virtuoso Spectre RF Environment ........... 13-52
Reviewing the tab_sp_test Schematic ............. 13-52
Setting Up the First Simulation ..... 13-53
Simulating the tab_sp_test Schematic ............. 13-55
Plotting the Results ...... 13-55
Reviewing the tab_sp_test2 Design................. 13-58
Setting Up the Second Simulation . 13-60
Simulating the tab_sp_test2 Schematic ........... 13-62
Plotting the Results ...... 13-62

Hi,
So if I use a current source in my design and later replace it with a MOSFET as current source with the rest of the circuit remaining same, will the voltage (Vds) be same as that with current source or it will change?
thanks