[SOLVED] Differential Amplifier simulation using Synopsys Hspice

Hello,
I want to ask some questions on this differential amplifier circuit that I referred in article "Design of CMOS Two-stage Operational Amplifier for ECG Monitoring System Using 90nm Technology by Moulahcene F Bouguechal N Benacer I Hanfoug S".



1. Can somebody explain to me about current mirror operation in simpler words?
2. If I want to build and simulate the schematic, do I need to add dc current source Iref in my schematic?

Im using Hspice with 90nm technology. Thank you.

ehsanaiman said:

View attachment 141437
1. Can somebody explain to me about current mirror operation in simpler words?

Click to expand...

The current mirror M8 -> M5 regenerates (or multiplies) Id(M5) = Id(M8) • (W/L(M5)) / (W/L(M8)) , similar for the mirror M8 -> M7
Id(M8) = Iref

ehsanaiman said:

2. If I want to build and simulate the schematic, do I need to add dc current source Iref in my schematic?

Click to expand...

Yes, sure. Use the idc current source.

Thank you for answering my questions, but I didnt get same gain as the circuit in article, although I have designed circuit according to all W/L ratio and capacitance. What is probably the cause of different gain obtained from same circuit with same design?

ehsanaiman said:

What is probably the cause of different gain obtained from same circuit with same design?

Click to expand...

Same process? If not, this will be the reason. If so, probably different simulation models.

It is possible if using different software; Cadence Virtuoso and Synopsys HSpice giving different simulation results even the same process technology?

ehsanaiman said:

It is possible if using different software; Cadence Virtuoso and Synopsys HSpice giving different simulation results even the same process technology?

Click to expand...

Yes, as I stated above: probably different simulation models.

Different design systems might not use the same simulator (Cadence Virtuoso: mainly Spectre ; Synopsys: HSpice), very probably they will use different transistor models.

You could try, find & check/compare them.

Alright sir, thank you for your fine explanations. Those will help me in designing new amplifier based on current circuit.