CiFET: A Class IV Current Conveyor – A Near-Ideal Wide-Band Monolithic Amplification Device – scalable to all IC process nodes without requiring any process extensionsJune 3, 20193 min read
The CiFET is the answer to the Multidisciplinary IEEE Open Access Journal request for “A Missing Active Device—Trancitor for a New Paradigm of Electronics”, and notes that these proposed new devices will directly transfer an input signal into a voltage output, providing a minimal circuit configuration to virtually continue Moore’s law. “In addition, this also leads to lower power consumption and higher circuit speed compared to a transistor-only circuit. In this regard, it should be required to find a trancitor to be another foundation of electronics along with transistors.”
A Missing Active Device - Trancitor for a New Paradigm of Electronics
SUNGSIK LEE, Department of Electronics Engineering, Pusan National University, South Korea
Figure 1 A theoretical list of elementary active devices deduced from 4 possible combinations of the current and voltage at the input and output, respectively. Here, it is found that trancitors are missing as CCVS or VCVS-type active devices.
The CiFET is both of these new types of devices, internally operating as a new fourth-generation current-conveyor, not constrained by semiconductor principles while yielding:
- High transResistance gain, operating with
- PPM linearity, over a
- Large ~Rail-to-Rail output signal swing, at
- Extra-wide ft bandwidth, having
- Zero iPort input current offset, with
- Symmetrical straight-line output swing around Vcm analog ground, with
- Inconsequential noise, while consuming
- Low-power, and incurring
- Insignificant semiconductor parametric sensitivity, or
- Temperature degradation over a >500°C range, while having
- Properties determined simply by ratioing physical layout geometry, while being
- Scalable to any IC process node including deep-nanoscale & FinFETs.
The CiFET fills both of the new lower CCVS & VCVS missing elementary active devices as well as replacing the existing upper CCCS & VCCS pair of devices with a new single PPM-linear device, functioning in any of the four operating modes. These CiFET operating modes can also be algebraically combined with PPM-precision and PPM-linearly for any combination of inputs to any combination of outputs, forming both voltage and current outputs concurrently.
Conventional FET amplifiers are current biased to engage transConductance (gm) gain — inversely CiFET amplifiers are voltage-biased to engage transResistance (rm) gain. Thus, conventional FET amplifies convert analog input voltage to a drain output current — inversely CiFET amplifiers convert analog input currents to a drain output voltage, which is an immensely practical alternative in that the CiFET is insensitive to parasitic wiring capacitance: CiFET current inputs encounter minimal AC-voltage wiring capacitance loading, while CiFET voltage outputs strongly drive wiring capacitance loads, resulting higher frequency operation.
Figure 2 Ultra-Linear high TransResistance Gain linearity and dynamic range.
Figure 3 CiFET common gate input signal to voltage output.
Both the bipolar and the equivalent FET multiplier circuits introduced nonlinear terms that cause distortion resulting in unwanted product terms that had to be filtered out in addition to being parametrically sensitive. The CiFET operating with PPM linearity avoids distortion and the unwanted frequencies generated.
Figure 4 CiFET example voltage gain boost over a low supply voltage as compared to an inverter.
The CiFET operates by means of altering segments of a common current path which passes through the series sequence of strength-ratioed semiconductor surface voltage-biased regions. These CiFET structures are the dual (or inverse) of conventional amplifier structures where a fixed bias-current is employed to bias an arrangement of threshold voltages normally including a differential pair.
Additionally, the CiFET minimizes capacitive coupling of external noise into the analog signal path at both the input and output, while internally isolating its input-signal return current-path injected-noise from output-signal Vcm voltage-referenced noise.
The CiFET can also linearly measure temperature over an extended range:
Figure 5 Test data overlay on simulation data plot of an example CiFET OpAmp circuit’s noise spectrum.
 Lee, S. (2018). A Missing Active Device–Trancitor for a New Paradigm of Electronics. IEEE Access, 6, 46962-46967. doi: 10.1109/access.2018.2866883
In summary we have demonstrated that the CiFET is the answer to the Multidisciplinary IEEE Open Access Journal request for “A Missing Active Device—Trancitor for a New Paradigm of Electronics”. It’s unique properties make it ideal for high performance, low power applications that overcome many of the shortcomings of existing devices.
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