A test Bench For Differential Circuits by Kenneth S. Kundert

Hi teachers,

I am new in Analog IC Design. I want to simulate frequency response of a fully differential OTA using 'A Test Bench for Differential Circuit by Kenneth S. Kundert. (The paper can be download from www.designers-guide.com).

When implementing a test bench, I follow exactly what have been written in the paper. I set Vdm=1V ac, Vcm=0V, Rid=Ric=Rod=Roc=0 ohm. Run ac analysis and probe differential output at node d.

The result is a bit strange for me. The phase response curve looks fine but the gain response curve is somehow funny. It looks like a response for high pass filter.( Gain increase linearly until it reaches certain level at certain frequency the gain become constant)

Anyone can tell me why is this happening? Is it something wrong with my setup? How about the setup for settling time and other related quantities?

thanks

Re: A test Bench For Differential Circuits by Kenneth S. Kun

it can only be used in spectra not hspice

Re: A test Bench For Differential Circuits by Kenneth S. Kun

Hi layes,

Why is it the test bench only can be implemented in Spectre not HSpice? Have you try it? what could be the problems when implementing in HSpice.

thanks

Re: A test Bench For Differential Circuits by Kenneth S. Kun

yes I would like use hspice
with a dc common voltage and
ac 500m with phase 0 and 180
not this test bench
because spectre not accuraca

Re: A test Bench For Differential Circuits by Kenneth S. Kun

Why Specture is not accurate for analog simulation ? Is Hspice better than Specture?