Voltage Controlled Resistor Cadence

This can be modelled using a voltage controlled current source with voltage controlled by table based voltage controlled current source.

Voltage controlled resistor cadence. Since the load is in series with the resistor r the output current is always proportional to the input voltage regardless of the load resistance within limits of course e g you won t be able to drive 10 ma through a 1 mω load unless you can find amplifiers that accept supply voltages up to 10 000 v or so. V i x r x vc. I v curves for a resistor and diode illustrating their linear and nonlinear resistance respectively. The anl misc lib library file contains subcircuit models for voltage controlled reactances and admittances.

Subckt tablecap 1 2 params. I then input 100k as the volt res conversion factor and voi la. Vcrs are most often built with field effect transistors fets. In this case we have a 5 ohm resistor.

C4 1pf m 0 5 vj 1 0 ecopy 3 6 1 2 1 0 vsense 0 6 0v. The jfet and the mosfet there are both floating voltage controlled resistors and grounded floating. In this application note we will illustrate the usage of voltage controlled impedance for controlling q of a series rlc filter network and changing the frequency of a wien bridge oscillator. Conventionally implementation in circuit simulators of resistor models that can support zero or small valued resistances is done by changing the model formulation from i v r which is preferred for nodal analysis but cannot be used for r 0 to v ir for small values of resistance or by collapsing the nodes between which the resistor is connected for r 0.

A voltage controlled resistor vcr is a three terminal active device with one input port and two output ports. These can be used to make voltage controlled resistors and capacitors. I solved the problem by using a voltage controlled resistor vcres from the analoglib on cadence and tying the positive node to vh and the negative terminal to vl. A simple addition to the above resistor model gives you a voltage controlled resistor.

Two types of fets are often used. All you need is a controlling voltage to multiply the resistor value. Here s a subcircuit for this device subckt vc res1 10k 1 2 4 5 eres 1 3 value i vsense 10k v 4 5 vsense 3 2 dc 0v ends.