s-Domain Linear Current Controlled Current Source (scccs)

The device output is defined through a transfer function given as a ratio of two polynomials in the complex variable s. Polynomials can be specified in terms of either coefficients or roots. The roots of the numerator are the zeros of the transfer function and the roots of the denominator are the poles.

To specify the polynomial in terms of the coefficients, you enter them as a vector in ascending order of the power of the variable s, starting from the constant term. For example, to specify a denominator of 3s^2 + 4s + 1, use denom=[1 4 3].

To specify a polynomial in terms of its roots, give the roots as a vector of complex frequencies (frequencies should be in radians/seconds). You must give both the real and imaginary parts of the root, even when the root is real. For the transfer function to be stable, all poles must have negative real values. When specifying a complex root, you should also specify its complex conjugate. However, if you omit the conjugate root, Spectre will supply the missing root and print a warning that a missing root was supplied. The roots can be in any order. For example, to specify poles of s = -1, s = 4j, s = -4j, s = -2 + 2j, and s = -2 - 2j; use poles=[-1 0 0 4 0 -4 -2 2 -2 -2].

Either the numerator or the denominator specification can be omitted. An omitted denominator or numerator is taken to be 1.

Notes on gain and gainfactor

The parameter gain is interpreted either as the DC gain or, if the function has zeros or poles at the origin, as a constant factor. gain has a default value of 1, so if you do not want to specify the DC gain, you should always use parameter gainfactor to disable parameter gain. When gainfactor is specified, gain is not valid any more. For example, if the instant statement is:

s1 (1 0 control 0) svcvs numer=[1 2] denom=[3 4]

the transfer function will be 2*(2s+1)/(4s+3). Factor 2 is applied to make the DC gain of the transfer function to be 1. If you just want the transfer function to be (2s+1)/(4s+3), specify gainfactor=1 to disable the default value of gain. In this example, the statement will be:

s1 (1 0 control 0) svcvs numer=[1 2] denom=[3 4] gainfactor=1

where the transfer function is 1*(2s+1)/(4s+3). 1 is the gainfactor.

This device is not supported within altergroup.

Sample Instance Statement

l1 (2 1) inductor l=15

sc1 (1 0) scccs probe=l1 zeros=[0 6 0 -6 2 -8 2 8] poles=[-1 0 0 64 0 -64 -2 8 -2 -8]

Instance Syntax

Name  sink  src scccs parameter=value ...

Instance Parameters

probe	Device through which the controlling current flows.
mprobe	The mprobe functions the same as probe except that it will divide the input current by the mfactor.
port=0	Index of the probe port through which the controlling current flows.
gain=1	DC gain or constant transfer function factor. See notes on gain and gainfactor for details.
gainfactor	Constant factor applied to transfer function. It disables the parameter gain.
numer=[...]	Vector of numerator coefficients.
denom=[...]	Vector of denominator coefficients.
zeros=[...]	Vector of complex zeros.
poles=[...]	Vector of complex poles.
m=1	Multiplicity factor.
tc1=0 1/C	Linear temperature coefficient.
tc2=0 C-2	Quadratic temperature coefficient.
trise=0.0K	Temperature frise from ambient.

Operating-Point Parameters

i (A)	Input current.
v (V)	Output voltage.
pwr (W)	Power dissipation.

Related Topics

Linear Voltage Controlled Current Source (vccs)

Current Sources

Circuit Components

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