Simulation package for tapped transformers and inductors

Hi I am interested in lowfrequency RF-simulation, and
I wonder if there is a software that lets me simulate circuits with
various types of tapped inductor and tapped transformers.

Especially I want to simulate an AM-demodulation stage
with an inductor cupled to the transistor collector, an inductor
at the emitter an iron core that couples them, and also coupling with the aid of the same ironcore to an LC-tank.

I also wonder what a switched capacitor circuit is.

Regards,
StoppTidigare

Ordinary SPICE simulators will handle your circuit at frequencies used in the AM and short wave broadcast bands. The tapped inductors are a series string of inductors with self and mutual inductance.

Switched capacitor circuits are a group of capacitors and switches. The switches connect different capacitors together and not at the switching frequency.

For instance, a RC time constant can be had without resistors by connecting a small capacitor to a big one to remove some of the change and then connecting the small capacitor to ground to get rid of the charge and repeating the process. These circuit functions only use capacitor ratios (which can be very precise) and low resistance FET switches. In the above example the RC time constant can be programmed with the switching frequency.

More complex combinations that are connected together with op amps can make ADC circuits and filters. Look at the Linear Technology web site for their switched capacitor filters and application notes on them. They are the industrial leader in this area.

Here is a spice simulation output of a single stage amplifier stage with the bare transistor model and the package parasitics added. Note how little the difference is at HF and lower. The left scale is dB of gain frequency response. This shows that you can use ordinary spice for your circuits.