JFET Device

The Spectre JFET device is translated as either a nonlinear N-type or a nonlinear P-type JFET device. For information on the JFET model, refer to JFET_Model:Junction Field Effect Transistor Model.

Example Spectre Command Line:

jk1 (net1 net2 0) jmod area=1

Spectre Netlist Syntax:

name nd ng ns [nb] mname [param=value]*

ADS Netlist Syntax:

vcvs:name p n ps ns [param=value]*

ADS Schematic Symbol:

Instance Parameters:

For information on parameter format, refer to Using Parameter Mapping Tables to Understand a Translation

Table 7-13. JFET Model Parameter Mapping

ADS Name	Unit	Default	Spectre Name	Unit	Default
Length	m		l	m
Width	m		w	m
Ad	m2		ad	m2
As	m2		as	m2
Pd	m		pd	m
Ps	m		ps	m
Nrd			nrd	m/m
Nrs			nrs	m/m
Region		on	region		triode
_M		1	m		1
Parameters not in Spectre Model
Temp	°C	25
NMOS		yes
PMOS		no
Mode		1
Noise		yes
			Parameters not in ADS Model
			trise	°C	0.0
			ld	m
			ls	m
			degradation		no
Temp = trise + temp ("temp" is an ADS global variable)

Comments:

• The referenced JFET_Model:Junction Field Effect Transistor Model model is read to determine which JFET device to use:

PJF keyword indicates JFET_PFET

NJF keyword indicates JFET_NFET

• The 4-port JFET is not available in ADS. The device will be skipped.

• If SCALE is specified, Value=Value*scale.

• If trise is provided, Temp=trise+temp (temp is an ADS global variable).

• The following syntax bay be ambiguous to the translator if the referenced model is not in the translated files:

Jid nd ng ns var1 var2

The translator is unable to determine which of the following should be used:

Jid nd ng ns na modelname

OR

Jid nd ng ns modelname area

Since the 4 port device is not available anyway, it will assume that modelname and area are specified. A warning message will be reported in the log file.